150 species: Worldwide. At least 40 species breed in North America.
|Adult Black-bellied Whistling-Duck, showing the distinctive gooselike neck typical of whistling-ducks.||Mallards and other dabbling ducks "tip up" to forage below the water's surface||Diving ducks, such as this Bufflehead, are strong divers and underwater swimmers.|
Ducks are placed with geese and swans in the family Anatidae, the waterfowl. They are medium-sized birds with stocky bodies, webbed feet, usually short tails, and often flat bills. Most show pronounced sexual dimorphism in plumage for most of the year, with males more strikingly colored and patterned. (Males of most species molt for a brief time after mating into a duller "eclipse plumage.") All ducks live in or near aquatic habitats, where they forage for aquatic vegetation, fish, insect larvae, and crustaceans. A few species also venture into cultivated lands to eat grain.
Tree ducks--here represented by the whistling-ducks and Wood and Muscovy Ducks--often roost or nest in trees. They feed by picking food from the water's surface or by submerging their heads. Whistling-ducks feed mostly at night, Wood and Muscovy Ducks by day. Dabbling ducks (Anas), like tree ducks, rarely dive for food; they feed either by "dabbling" with the bill to pick items from the water's surface or by "tipping up"--reaching below the surface, tail in the air. Some use their bills to strain water and mud or to strip seeds from vegetation. Diving ducks form a diverse group that includes the bay ducks, sea ducks, mergansers, and stiff-tailed ducks. All forage by diving underwater, sometimes to considerable depths. They swim with wings closed, propelled by their feet, which are set farther back on the body than in dabbling ducks.
Bay ducks (Aythya), also called pochards, forage in open waters. Male bay ducks may be recognized by their striking glossy red, purple, or green heads. Sea ducks include Long-tailed and Harlequin Ducks, scoters, and eiders, which feed around rocky shores on shellfish, and the goldeneyes and Bufflehead, which are more widely distributed inland in winter.
Mergansers have a long, narrow bill, with saw-like serrations for grasping slippery prey.
Stiff-tailed ducks are represented in North America by Ruddy and Masked Ducks, both small, stocky species with tails that are often cocked upward.
Most ducks nest in remote northern lakes and marshes and migrate southward for the winter; they are highly gregarious, sometimes forming winter flocks in the thousands. Courtship, usually occurring through winter and into spring, involves calling, exaggerated head movements, and flight displays by males or by both sexes. Despite continuing work by conservation groups, most ducks are in decline in North America, with the exception of Green-winged Teal and Gadwall.
Geese and Swans
|Snow Goose has both dark and light morphs; the dark morph is often called "Blue Goose"|
Geese (Chen, Anser, and Branta) and swans (Cygnus) are also members of the family Anatidae, the waterfowl. Like ducks, geese and swans have stocky bodies, webbed feet, and usually short tails. They differ in their bills, which tend to be deeper at the base, and in their size: most geese are larger than ducks, and swans are enormous--up to 58 (1.5m) long, with a nearly 78 (2.1m) wingspan. Unlike ducks, geese and swans are usually not sexually dimorphic in plumage, although many species show marked differences in size and voice between the sexes. Snow and Ross's Geese are unique among the world's geese in showing plumage polymorphism: both have a light morph, a dark morph, and several intermediate plumages. Swans and geese eat aquatic vegetation, and most geese also graze on land on short grasses and grains. Like dabbling ducks, they don't dive while foraging, but their long necks enable them to reach deeper underwater when dabbling or tipping up. Most swans and geese nest on tundra or remote western lakes and marshes; introduced populations of Canada Goose also nest in urban areas. Courtship displays in swans and geese are minor or absent, as pairs usually mate for life. In autumn most northern-nesting geese and swans migrate southward to gather in huge flocks at traditional wintering grounds, often on agricultural lands.
|Adult Emperor Goose.Populations of this species appear to be declining in Alaska and Siberia.|
Dozens of nonnative waterfowl species are kept in zoos and private collections; of these, many have escaped captivity, although few have become established as nesting birds in North America. (One exception is Mute Swan, introduced to North America from Europe.) These escapees from captivity can make it difficult to discern patterns of occurrence of rare Eurasian species, such as Whooper Swan, Falcated Duck, and Baikal Teal.
Swans and geese, like ducks, have long been hunted as game birds, and their populations declined in the twentieth century because of over harvesting as well as habitat loss. Hunters joined forces with conservationists to reverse these trends, and wildlife refuges and new management practices now protect waterfowl and their habitats. As a result, most North American geese and swans now have stable or increasing populations.
Identification of Swans
Trumpeter Swan, Whistling Swan (American subspecies of Tundra Swan), and Bewick's Swan (Eurasian subspecies of Tundra Swan) are very similar in appearance: large and white with a black bill. Adults are best distinguished by differences in bill shape and the amount of yellow on the lores or base of the maxilla.
|Trumpeter Swan adult--Black maxilla straight at gape; forehead feathers form V-shape; no yellow on lores; angle of bill at lores looks more open, less pinched, than in Whistling.||Whistling Swan adult--Black maxilla curved at gape; forehead feathers form U-shape; less yellow on lores than Bewick's (15 percent lack yellow).||Bewick's Swan adult--Extensive yellow on base of maxilla. Whooper Swan, also a Eurasian vagrant, similar but much larger.|
5 species: Northern Hemisphere. All five species breed or have bred in North America.
|Common Loon with chick: both parents feed the young, even after they fledge.|
Loons are members of the ancient family Gaviidae, fossils of which date back tens of millions of years. They are heavyset diving birds with dagger-like bills that they use to spear fish, crustaceans, and other aquatic prey. Like grebes, loons have feet set far back on the body, an adaptation for agile pursuit of prey under water. The larger species may spend more than a minute below the water's surface and dive to depths of several hundred feet.
Loons nest on remote lakes or sheltered coastlines in Canada and Alaska; Common Loon also nests in the northern United States. Their elaborate courtship displays involve synchronized swimming, chasing, and bill movements, and males and females also give a variety of yodeling, quacking, and whinnying calls. In autumn loons migrate southward to winter on large lakes and ocean coasts, where they can sometimes be observed in large, loose flocks; Yellow-billed Loon is usually seen singly, especially in the lower 48 states.
Common Loon, which nests on boreal lakes farther south than other loons, faces a host of conservation problems: acidification of the lakes, development (resulting in pollution of the lakes and disturbance by recreational boaters), and poisoning by ingestion of lead sinkers used in fishing tackle.
Identification of Loons:
Loons are often seen from a long distance, resting on the water or actively feeding, and a spotting scope is useful for studying them. The colorful and boldly patterned breeding plumages usually present little difficulty for identification; non-breeding plumages, however, require careful study. Concentrate on the head, neck, and bill, paying attention to pattern as well as overall shape. Size can be hard to judge at a distance.
Loons in flight
|Common Loon||Pacific Loon|
Flying loons can be difficult to identify, but the different shapes and flight styles of the species provide useful clues for identification. The larger two loon species fly with slow wing beats and hold the wings perpendicular to the body. The smaller three species fly with more rapid wing beats, holding the wings slightly swept back from the body.
Loons are quite difficult to distinguish from each other in flight; look for Arctic's white flanks. They differ from the larger loons in their more compact shapes and less obvious trailing feet, and they are larger and more substantial and appear darker overall than the slimmer, paler Red-throated Loon. Red-throated often carries its slender neck well below the level of the body in flight, raises and lowers its head, and moves its head from side to side, unlike other loon species. It also raises the wings quite high in flight and has a noticeably deeper wing stroke than other loon species.
21 species: Worldwide. Seven species breed in North America.
Grebes are members of a group of birds (family Podicipedidae) that probably arose in South America millions of years ago. They share qualities with both waterfowl and loons, but they have toes that are lobed rather than webbed; tails so tiny as to be almost invisible; and fluffy, almost fur-like plumage in the flanks and under tail. The bills of grebes also differ from those of other diving birds, varying from blunt and pointed in the unique Pied-billed Grebe to stiletto-like in Clark's and Western Grebes. Grebe bodies are well adapted to hunting underwater for fish, crustaceans, and other aquatic prey; smaller species can regulate their buoyancy and submerge without diving by compressing the body plumage. Grebes nest on freshwater lakes and ponds. Their courtship displays involve bobbing and bowing, and pairs of some species engage in an almost ballet like footrace across the water's surface. In fall grebes in northern areas leave the nesting grounds for coastal and inland wintering grounds to the south. Some grebe populations have declined in recent decades. Horned Grebes have disappeared from the northern prairie pothole country, and at Mono Lake, California, the flocks of Eared Grebes that once numbered more than a million are lately reduced to less than 200,000.
Grebes in Flight--Loons can be confused with larger grebes in flight, but the grebes always show much white in the wings, visible even at a distance: all have white secondaries, and the larger species have some white upperwing coverts as well. Their white wing patches, as well as their very thin necks, make grebes distinguishable from loons under most conditions.
22 species: Seacoasts of Northern Hemisphere. Twenty species breed in North America.
The murres, murrelets, auklets, auks (Razorbill and Dovekie), puffins, and guillemots of the family Alcidae--commonly called "alcids"--are marine birds with relatively short wings, webbed feet, and well-insulated, compact bodies. Perfectly suited to a life spent in cold, rough seas, alcids are awkward, almost penguin-like, on land and come to shore mostly to nest or when ailing. This family shows great diversity in bill structure and in size, ranging from the petite Least Auklet, the world's smallest alcid (3 oz/85g), to the extinct, flightless Great Auk (11 lbs/5kg). Alcids have counter shaded plumages that help them escape notice of both aerial and marine predators. Some species show different plumages in summer and winter; puffins and auklets sport head plumes and brightly colored bills in breeding dress, which they shed after nesting. Birds in this group can be confused with ducks, grebes, and loons at a distance, but their shape and distinctive manner of flight--low to the water, with rapid wing beats--quickly distinguish them from other water birds.
Alcids dive for their prey, using both their wings and feet for propulsion and steering.
Alcids use both feet and wings when foraging, appearing to "fly" under water. The larger species, which feed on fish and squid, can dive to depths of 6008 (180m); smaller species may dive to 1508 (45m) for copepods, small jellyfish, and plankton. While some species stay close to land year-round, most feed in pelagic waters during the non-breeding season.
|The Great Auk, once found on islands from eastern Canada to Scotland, was the largest alcid. By 1800 the last Canadian colony, on Funk Island, had been eliminated by hunters, who took eggs, chicks and adults for food and bait. The species was last seen in 1844.|
Alcids nest mostly on the ocean's edge in cliffs, rock crevices, or burrows; many Marbled Murrelets nest high in coniferous trees and often well inland. Most larger species nest in colonies, while smaller species, such as Kittlitz's Murrelet and the guillemots, are solitary nesters. Some smaller alcids, including Xantus's Murrelet, are strictly nocturnal on the breeding grounds, which helps them avoid predators such as gulls. Courtship among alcids may involve loud braying calls and much movement of the head. Puffins and auklets show off their bills and head plumes in displays. Ancient Murrelets sit in trees and "sing" above their burrow entrances. After fledging, young birds take to the ocean, often accompanied by a parent. Young birds may spend up to eight years on the open ocean before returning to the breeding colonies. Like most pelagic birds, alcids exhibit strong natal philopatry, returning to the area where they were hatched.
The habits and habitats of alcids put them in the way of many dangers at sea, such as predatory fish. But by far the greatest threats to their survival are manmade: hundreds of thousands have been killed by oil spills and other pollution or by entanglement in gill nets.
8 species: Nearly worldwide. Two species breed in North America.
Pelicans are huge birds with webbed feet, very long bills, and enormous gular (throat) pouches. The American White Pelican inhabits inland waters and coastal lagoons, catching fish at the surface, while the Brown Pelican is exclusively coastal and plunge dives from the air to catch its prey. Flocks of both species fly in long lines, alternately flapping and gliding, or occasionally soaring high in the sky.
38 species: Worldwide. Six species breed in North America.
These are large birds, usually black, with long necks, long hooked bills, and webbed feet. The feet of these expert divers are located far back on the body to give them forward thrust underwater; on land cormorants stand upright, often with their wings partially extended to dry. In the air, they fly in long lines or wedge shaped formations.
4 species: Tropical or subtropical regions of the world. One species breeds in North America.
These large, web-footed birds have long slender necks and pointed spear-like bills with which they impale fish. They inhabit inland, freshwater lakes, streams, and marshes, and nest in trees and bushes.
3 species: Tropical and subtropical oceans of the world.
These birds resemble huge terns with long tail streamers. They are locally numerous and easy to see near their nesting colonies on oceanic islands but outside the breeding season they roam widely over the ocean and are usually solitary. They feed on squid and small fish.
|Blue-footed Boobies use their brightly colored feet in courtship displays.|
9 species: Nearly worldwide on islands and coasts. Only one species breeds in North America.
Boobies and gannets are large birds with long pointed bills, webbed feet, and pointed wings, adapted for plunge diving for fish from great heights into the ocean. They nest on steep cliffs and rocky islands, and sometimes in trees.
5 species: Tropical oceans of the world. In North America one species breeds in extreme southern Florida on the Marquesas Keys off Key West.
These are large, extremely long-winged birds with long, deeply forked tails, hooded bills, and webbed feet. Males have inflatable throat patches. Nesting chiefly on oceanic islands, they rob other seabirds, forcing them to disgorge the fish they have caught.
All pelecaniforms have completely webbed feet and feed largely on fish and other aquatic prey. All but the tropicbirds nest in colonies, some of which can involve many thousands of birds with nests only a few inches apart. The tern like tropicbirds are the smallest of the order, with wingspans of a mere 38 (1m); American White Pelican, with a nearly 98 (3m) wingspan, is almost as heavy as a swan.
Pelecaniforms have evolved to exploit both marine and freshwater habitats. Some are specialized foragers; the fish-spearing Anhinga, for example, is limited to freshwater lakes and swamps. Others, such as Double-crested Cormorant, forage equally well in rivers, ponds, and ocean. The most pelagic of the pelecaniforms are the tropicbirds; they spend most of their lives over the open ocean, diving from great heights in the air to seize fish, squid, and cuttlefish. Boobies, gannets, and Brown Pelican also dive on fish from the air, mostly in marine environments, often near land. Magnificent Frigatebird swoops over the ocean's surface to pluck prey items or harasses other seabirds and steals their catches. Cormorants swim on the surface, diving under to seize fish and crustaceans.
American White Pelican lowers its 5-gallon bill pouch into the water as it swims to trap fish, crayfish, and other prey.
Courtship among pelecaniforms is often spectacular. Sulids perform graceful, dancelike promenades, point their bills skyward, and use their brightly colored feet-- brilliant red, blue, or yellow in the tropical boobies--in exaggerated displays. Breeding male cormorants and pelicans attract females with colorful gular pouches and head or flank feathering and also engage in loud calls, posturing, and wing movements. Male boobies often present females with tokens, such as rocks or feathers; male darters, cormorants, and pelicans may offer gifts of nesting material. The display of Magnificent Frigatebird takes the prize: the male inflates an enormous, cherry red gular sac like a great balloon and clatters his long bill as the female looks on.
North American pelecaniform populations are generally stable, and some are even increasing steadily, such as those of Double-crested Cormorant and Brown Pelican, two species that have recovered remarkably well after the banning of DDT.
Identification of Pelecaniforms:
Shape, locomotion, and behavior offer important clues to the identification of pelecaniforms. Cormorants and anhingas, for example, are superficially similar--both long-bodied, long-necked, surface-diving birds--but they display many differences in shape, movement, and foraging manner.
Cormorants dive like loons, plunging headfirst. Great and Pelagic Cormorants often leap upward, almost clearing the water before submerging; Double-crested dives without the leap.
When foraging, an Anhinga sinks slowly into the water and often exposes only the head and part of the neck, keeping most of the body submerged--something cormorants never do.
Double-crested shows the most robust form, with long, rather broad wings and a heavy neck that is kinked in flight. Brandt's also looks large and full-winged, but its wings and tail both appear shorter than those of Double-crested, and it usually holds its neck straight, not kinked. Pelagic is very different, with its slender head, long, thin, snakelike neck, and long, narrow wings. Red-faced Cormorant, sometimes confused with Pelagic where the two are found together in coastal Alaska, has fuller wings and a heavier, more distinct head.
Cormorants in Flight
Brandt's, Pelagic, and Double-crested Cormorants can often be seen from shore on the Pacific coast. Overall size and shape of head and neck help distinguish these species on the water or in flight.
Diving behavior differs among the aerial plunge-divers: the tropicbirds, boobies, and gannets. These pelagic birds are often seen at great distances over the ocean; their differences in structure and behavior provide good clues for identification.
Boobies, especially the smaller species, can be distinguished from gannets by their narrower wing shape and their style of diving for prey: boobies often dive at shallow angles, whereas gannets usually dive from directly above prey. Tropicbirds are easily confused with Royal Tern at a distance (especially younger tropicbirds that lack the long tail streamers of adults); both tropicbirds and terns dive from high in the air, but tropicbirds typically close the wings, plunging into the ocean like a large dart. Tropicbirds' wing beats are also more rapid than the wing beats of most terns (recalling pigeons).
14 species: Mostly in the oceans of the Southern Hemisphere, all distinctly migratory. Three visit North America when not breeding.
These seabirds are goose-sized or larger, with powerful bill, hooded at the tip; tube-like nostrils; and very long, narrow wings, that allow them to glide effortlessly over the waves, picking live squid or floating edibles form the ocean. They lay one egg in a scrape or mound on the beach, mainly on islands but also on remote coasts.
80 species: Worldwide. Only three species breed in North America, but many winter here.
Members of this family, mainly oceanic in the non-breeding season, nest in burrows on islands and along coasts, where they are chiefly nocturnal. These birds have tubular nostrils, webbed feet, and long pointed wings that are held stiffly during prolonged effortless glides low over the waves. As in the closely related storm-petrels, the nostrils are enclosed in horny tubes on top of the bill. Most species feed on fish, squid, crustaceans, or plankton. Among North American species shearwaters tend to be larger than petrels.
21 species: Worldwide in tropical and temperate oceans. Four species breed in North America.
These small birds flutter over the surface of the water, where they feed on small crustaceans, fish, and plankton. Like the shearwaters, they have tubular nostrils on top of the bill. Most species are black, and some have white on the rump, but a few are gray. Because they are small and usually seen from the dick of a pitching boat, they can be difficult to identify. Flight characteristics, rather than color an pattern, are often the best clues. Storm-petrels nest in burrows on offshore island and isolated coasts, which they visit only at night.
"Tubenose" is a collective term for four closely related pelagic seabird families grouped in the order Procellariiformes: the goose-sized albatrosses (Diomedeidae); the gull-sized shearwaters, fulmars, and petrels (Procellariidae); the much smaller storm-petrels (Hydrobatidae); and the diving-petrels (Pelecanoididae), found only in the Southern Hemisphere. Tubenoses have stout bodies and heads and webbed feet for swimming (and diving, in some species). They are named for their tubed nostrils, or naricorns -- specialized parts of the bill used both to detect scents and to extrude salt extracted from seawater by the salt glands. Because they can drink salt water, tubenoses are able to spend years at a time at sea. Their pelagic habits are also aided by buoyant plumages and, in most cases, aerodynamic wing structures, supreme adaptations for harnessing breezes and traveling great distances with minimal expenditure of energy. Recently, an albatross fitted with a satellite transmitter was found to travel 13,670 miles (22,000km) around the world in 46 days; several others are known to have circled the globe twice in 18 months! Tubenoses feed on a great variety of marine organisms, from plankton (eaten by the smallest species) to squid (by the largest) and many types of crustaceans, fish, cephalopods, and carrion in between. Their keen senses of sight and smell guide them to food; some species forage at night, relying on bioluminescence in their prey. Most tubenoses seize prey at the water's surface with strong, sharp-edged bills that have a hooked unguis (nail) at the tip of the maxilla. Several shearwaters, such as the abundant Sooty Shearwater, readily dive to moderate depths--up to 608 (18m)--using both wings and feet to pursue prey underwater.
Tubenoses nest in colonies mostly on remote oceanic islands far from familiar birding locations. Most of the smaller species, such as storm-petrels, enter and leave burrows only at night in order to avoid predators. Northern Fulmar nests high on cliffs in the Arctic, in an area of almost perpetual daylight, where it discourages predators by expelling a stream of stomach acid.
|Courtship among Laysan Albatrosses involves a complex series of exaggerated poses, each accompanied by different vocalizations or bill sounds.|
Courtship among tubenoses usually involves paired flights at sea and around the breeding grounds (these can take place both day and night) and allopreening, in which members of a pair preen each other's plumage. Albatrosses, which mate for life and may live to be 75 years old, have a more elaborate set of courtship displays than the smaller species: male and female perform a series of calls and fantastic, stylized postures in a specific sequence. After courtship and copulation, tubenoses return to sea for a period, to gain weight needed to produce their single egg.
Like other marine birds, tubenoses are threatened by pollution of many sorts (plastic debris has been found in the stomachs of many species), oil spills, over harvesting of prey species, and long lining, a fishing practice that threatens several larger petrels and albatrosses with extinction in the near future.
Identification of Tubenoses:
The majority of tubenoses are pelagic species and as such are rarely seen near shore; most people encounter them while at sea. The bills of all tubenoses have tubed nostrils but differ in length, depth, and shape. On pelagic birding trips, tubenoses are often lured close with food, and their different bill structures can then be observed.
|Yellow-nosed Albatross||Wedge-tailed Shearwater|
|Black-footed Albatross||Leach's Storm-petrel||Northern Fulmar|
Albatrosses, the largest tubenoses, have large bills made of multiple plates. The naricorns are located on opposite sides of the bill. (In the smaller tubenoses the naricorns join at the base of the culmen.) The culminicorn, a distinct plate located along the top ridge of the culmen, is brightly colored in some albatrosses, such as Yellow-nosed. Shearwaters have long bills, like albatrosses, but their bills are less deep. Petrels and fulmars have shorter, stubbier bills. The culmen of all tubenoses ends in an arched, sharp nail (unguis) that is used for tearing prey and gripping slippery catches like squid. The nail is bulbous in some species (Northern Fulmar) and heavily hooked in others (Black-capped Petrel). In small petrels (such as Cook's and Bermuda), the nail blends more with the rest of the bill. Storm petrels all have very small bills; there are subtle differences in length and depth, but these are rarely useful for species identification.
|Greater Shearwater||Layson Albatross|
Tubenoses in Flight: The flight behavior of tubenoses varies according to wind speed, but, as with raptors, a seabird's various flight styles can be learned with patient, repeated observation. A bird's wing shape is directly related to its manner of flight.
The wings of albatrosses are very long and rather narrow, a shape that is described in aerodynamic terms as having a very high "aspect ratio" (the relationship of length to width). Tubenoses with such wing shapes fly in long, graceful arcs, following a roller coaster--like path, and flap only occasionally (less so in higher winds).
The wings of Audubon's Shearwater, by comparison, are short and wide and have a lower aspect ratio but a higher "wingloading"--the relationship between body weight and overall wing area. Thus Audubon's tends to flap rapidly between glides, although when winds are brisk it is able to gain more lift and flaps much less.
129 species: Worldwide. Thirty-four species breed in North America.
Jaegers, skuas, skimmers, gulls (including kittiwakes), and terns (including noddies) are often grouped into a single family, Laridae. All larids are small to medium sized waterbirds with webbed feet and relatively long wings. The group includes very familiar birds, such as the gulls that wheel around the seashore or above fast food franchises, as well as pelagic species rarely observed on land in North America, such as the skuas. Black Skimmer differs markedly from other larids (and all other birds) in its outsized bill, with mandible longer than maxilla. In 2006, the American Ornithologists' Union moved jaegers and skuas into their own family, Stercorariidae.
The so-called "seagull" is represented on this continent by no fewer than 30 species, from the world's largest, the goose-sized Great Black-backed Gull, to the world's smallest, the dove-sized Little Gull. Bill size and shape in gulls is very much tied to body size: larger species have heavier, deeper bills, while the smallest gulls have rather thin, tern like bills. Terns are less adaptable than gulls in most respects, and they also show relatively less diversity in structure and plumage. The mostly dark plumaged jaegers and skuas recall birds of prey: jaegers, with their pointed wings and swift flight, resemble falcons; skuas, with their heavy bodies and bills and aggressive manner, recall hawks.
Larids show a remarkable range of foraging techniques. Most gulls are adapted to seizing fish or other prey from the water's surface; others pick fruit on the wing, flycatch, dig for grubs and worms, and even drop shellfish onto rocks to break them open. Few birds are better adapted to manmade environments than gulls, which forage in an astonishing array of places: city parks and streets, landfills, sewage treatment plants, agricultural fields, and hydroelectric plants, to name only a few. Most terns forage by diving, but some also fly-catch insects or pick prey from the water's surface. Skimmers forage by lowering the mandible into the water when flying and snapping the bill shut upon sensing prey. Jaegers and skuas derive much of their food in the manner of raptors, either through direct predation of small mammals and birds or by stealing food from other birds. Like gulls, jaegers and skuas are omnivores.
Most larids nest in colonies, sometimes very large ones, though the jaegers, skuas, and larger gulls often nest solitarily and defend large territories. Most species nest on the ground or on sea-cliffs, with little in the way of a true nest; a few, such as noddies and Bonaparte's Gull, nest in trees. Courtship usually consists of ritualized posturing, parading, and calling; some species make offerings of small fish or other items. Gulls, particularly the larger species, have "long calls" that they use in a variety of contexts, including pair-bonding. Both parents feed their young.
Gull populations are mostly stable or increasing. Terns and Black Skimmers, however, are vulnerable to a variety of disturbances at nesting colonies, and productivity in several species of terns is considered low.
Identification of Larids:
|Herring, Great Black-backed, and Glaucous Gulls.|
The array of species and plumages in a large flock of gulls and terns can overwhelm the inexperienced birder. A first step in larid identification is to make separate "scans" for differences in overall size, bill structure, upperparts color, and leg color, and thus begin to separate the flock into species. In gulls study eye color and wingtip pattern, which vary among individuals in a species but can provide additional information. It is important to learn the extent of variation within a species. First-winter Herring Gulls, for example, vary in body and bill sizes and plumage, and adults vary in leg color, eye color, head markings, and wingtip patterns.
The family Laridae presents numerous identification pitfalls. Juvenile gulls of the largest species are darker than adults (some quite dark brown), and most have dark bills; they can be mistaken for jaegers or skuas, which also have dark bills (except when very young). Juvenile Heermann's Gull, for example, is sooty brown overall and easily mistaken for a jaeger; its initially dark bill acquires a pale base within a few months, which separates it from older jaegers. Identifying gulls is further complicated by hybridization, especially among four-year gulls (see p. 120). In some areas, hybrid gulls and their backcrosses are abundant. In the coastal Northwest, for instance, Glaucous-winged/Western Gull hybrids outnumber the parental types, and other hybrids are also common. Many hybrids show characteristics that are intermediate between the parent species; some hybrids cannot be identified.
|Western Gull||Heermann's Gull||Parasitic Jaeger||South Polar Skua|
Larid Bills -- The larger larids--skuas, Black Skimmer, and large gulls--have heavy bills, and the smallest species (Least Tern and Little Gull) have thin or short bills. Most gulls have moderately long but rather deep bills in which the culmen curves gently at the tip; terns and some small gulls have more slender, pointed bills. Male gulls tend to be larger than females, and their bills are correspondingly heavier. The smaller species in the many confusing "gull pairs"-- Franklin's and Laughing, Iceland and Thayer's, Little and Bonaparte's, California and Herring-- nearly always have a more delicate (shallower and sometimes shorter) bill. The same is true of "tern pairs," such as Elegant and Royal, Arctic and Common, and White-winged and Black. Runt individuals and small females can have bills that are quite small for the species; a petite Ring-billed Gull, for instance, may resemble a Mew Gull.
Jaeger and skua bills have a fairly strong nail at the end of the culmen (like the bills of tubenoses). The extent of the nail and the size and position of the gonys (the point on the mandible where the two sides fuse, usually visible as a slight downward-projecting point) relative to the rest of the bill differ among the jaegers. Pomarine Jaeger has a heavy, skualike bill with a distinct gonys and a relatively small nail. The bill of the intermediate Parasitic Jaeger has a slighter gonys, and the nail occupies about a third of the bill overall. The diminutive Longtailed Jaeger has the smallest bill, with the nail extending almost half the bill length and the gonys almost at the bill's midpoint. The two skuas also differ in bill size, with Great having a thicker bill than South Polar.
Gull Plumages and Molts:
Gulls hatch with a fuzzy coat of natal down and molt through several plumages before attaining adult plumage. Molts usually take several months to complete. Most of the smaller species of gulls are two-year gulls: they hatch in the breeding season of one calendar year and mature in the next (in just over 12 months). Intermediate-sized gulls, such as Ring-billed, generally take three calendar years (just over two full years) to attain adult plumage and thus are "three-year" gulls. Most of the largest species, such as Herring Gull, are adults at just over three years of age--a span of four calendar years; these are four-year gulls. (There are exceptions: the tiny Little Gull and the large Yellow-footed Gull are three-year gulls, and medium-sized Heermann's Gull appears to be a four-year species.) As adults, gulls undergo partial molts of head and body feathers twice a year, in spring and fall. They molt their flight feathers once a year, after breeding (Franklin's replaces its flight feathers twice a year); gulls in summer appear ragged, as their worn remiges and rectrices are replaced.
Two-year gulls, such as Bonaparte's, have striking dorsal patterns in the juvenal plumage, and almost all of them (Ivory Gull and Red-legged Kittiwake excepted) show a prominent carpal bar or dark secondary coverts as juveniles. Soon after they are flying well, they molt the head and body feathers, along with some coverts, which produces first-winter plumage, also called first-basic plumage. (First-winter plumage is similar to juvenal plumage and often depicted in this guide instead of juvenal.) The head and body feathers are then molted again in spring, resulting in first-summer plumage, or first-alternate plumage. (First-summer plumage, usually similar to first-winter plumage, is not depicted in this guide.) The whole plumage, including remiges and rectrices, is replaced in the autumn of the birds' second year, resulting by wintertime in adult non-breeding plumage, or definitive basic plumage. In spring, the birds again molt head and body feathers to attain adult breeding plumage (definitive alternate plumage), including in some smaller gulls a dark hood.
Three-year gulls in North America include Ring-billed Gull and the exceptional Little and Yellow-footed Gulls (noted above), plus Mew, Franklin's, Laughing, and Black-tailed Gulls. Juvenile three-year gulls are not as strikingly marked as the two-year species; they are generally more brownish above and lack the neat carpal markings of the smaller species, although Little Gull shows very contrasting markings above. The progression of plumages in three-year gulls is the same as for two-year gulls, but the three-years take about a year more than two-year gulls and undergo two additional molts to attain adult non-breeding plumage. (Their additional plumages--second winter and second summer--are similar to adult plumage and are not depicted here.) One difference between the subadult or near-adult plumages and adult plumages of this group can be seen in the primary tips: adults (except for Black-tailed Gull) have either white tips to the primaries or white "mirrors" (spots of white near the tip); most younger birds lack these.
|Juvenal plumage (intransition to 1st winter)||1st winter||2nd winter||Breeding adult|
Four-year gulls, represented here by Herring Gull, include the larger "white-headed" gulls--that is, those that have pure white heads (no hoods) in adult breeding plumage. The non-breeding (winter) plumages of many of these species are very similar to breeding plumages except for darker markings in the head, which can be moderate flecking to very heavy mottling. Gulls in this group have nine different plumages, compared to the seven plumages of three-year species and five plumages of two-year species. The plumages of four-year gulls can be challenging for the beginner. Their names are rendered just as those for two-year and three-year species--(juvenal, first winter/first basic, first summer/first alternate)--but they extend another year, into a third winter and third summer, before adult plumage appears. When learning the plumages of four-year gulls, it is easiest to begin with adult plumages, learn first-winter plumages next, and then tackle the plumages in between. The second- and third-winter plumages are the scarcest in any given flock (because of survivorship) and often resemble the adult closely enough to be recognizable once that plumage is learned well.
|Juvenal plumage||1st winter||2nd winter||3rd winter||breeding adult|
Tern Plumages and Molts:
The plumages of most terns are deceptively simple--white below and pale gray above, with a dark cap, a mostly white tail, and some dark pigmentation in the primaries. The patterns in these features, however, vary in confusing ways because of the complex molts in terns. An understanding of these molts is important for identification.
|young juvenile||older juvenile||1st summer||winter adult|
Common Tern is widespread and the species to which other medium-sized terns are often compared. Like other terns, Common holds a juvenal plumage for a short time. By autumn the brownish back and covert edges of this plumage have worn to gray, and the body plumage begins to molt into first-winter (or first-basic) plumage, a plumage fully acquired on the South American wintering grounds.
Many subadult birds stay the year in South America, but a few return in spring to North America in a first-summer plumage, which resembles a non-breeding adult in the head but a late-summer adult in wing wear (the molt schedule of these subadults is still a few months behind that of adults). By the next year's second-summer plumage, many Common Terns look like full adults, but some retain white flecking in the head and belly or a trace of a carpal bar. Most Commons reach full adulthood and begin breeding in their third calendar year, at about two years of age. Adult breeding (or alternate) plumage and adult non-breeding (basic) plumage alternate throughout the tern's life.
Common Tern undergoes two incomplete molts of its remiges per year, as opposed to the single complete molt of most larids. It molts the inner primaries in late summer after breeding and then resumes southward migration. The remaining remiges are molted through midwinter; once this molt is complete, the inner primaries that were new in September have become worn, so they are replaced before the birds set out for the Northern Hemisphere, as are the body, head, and other feathers, to bring the bird into full breeding plumage.
When it arrives at the nesting areas, then, an adult Common Tern has fresh inner primaries but older outer primaries. Both sets of feathers are fresh enough to look pale from above; this pale appearance is caused by tiny barbules that show up as a powdery patina on the feathers. As the nesting season wears on, the barbules wear off, so that the older outer primaries show up as contrastingly darker than the paler, younger inner primaries. By contrast, Arctic Tern has a complete molt of the remiges, and the primaries look evenly pale on birds in North America
64 species: Worldwide. Twelve species breed in North America.
|Snowy Egret's courtship display includes fanning its abundant nuptial plumes.|
Some of these large to medium sized, long-legged wading birds have long necks that they fold over their backs in flight. Bitterns and herons have long bills for catching prey, and their toes are unwebbed. Many species nest in colonies in trees and bushes. Some species have elaborate plumes during the breeding season.
Herons and egrets are the most familiar members of the family Ardeidae. These birds are often seen posed elegantly at the edge of a pond or stream, watching for fish and frogs. They spear prey with lightning quick jabs propelled by strong muscles in their long necks. Cattle Egret is exceptional among ardeids in that it forages mostly in fields, following livestock or tractors that stir up insects, its chief prey.
Bitterns nest in freshwater or brackish marshes, where they often stay hidden in reed beds and are hard to find.
Night-herons forage extensively at night, as their name implies, but are still usually easier to detect than the bitterns.
Most ardeids nest in colonies in trees or reed beds. Courtship involves a variety of stylized postures, garrulous calls, and, in some species, a display of specialized, wispy breeding, or nuptial, plumes called aigrettes (the French word for these feathers that gave rise to the English name egret). After the breeding season, both adults and young birds may wander widely in search of food; by autumn most herons and egrets begin migration toward southern-tier states or the tropics.
33 species: Chiefly tropical regions of the world.
Four species breed in North America, including the colorful Roseate Spoonbill. The bills of ibises are long and curved downward; those of spoonbills are straight and spatulate. They are aquatic birds that feed on fish, frogs, insects and other small animals in the water. They nest in colonies in trees and bushes, often with herons.
Ibises and spoonbills are specialized foragers, as their unusual bill shapes indicate. They usually sweep their bills from side to side in shallow water, creating currents that dislodge aquatic prey. Ibises also forage by touch in mud or soft soil, using their long, curved bills to extract worms, crayfish, small fish, and amphibians. Both spoonbills and ibises have been found wandering far from their typical ranges, especially in recent years.
17 species: Chiefly tropical regions of the world. Only one species breeds in North America.
Storks are large, long-legged, long-necked and long-billed birds that live chiefly in open marshy country. They nest either singly or in colonies in trees and bushes, often with herons and ibises. They feed on all sorts of animal matter and a few species eat carrion.
Wood Stork and the enormous Jabiru, a vagrant from Central America, are the only native storks found in the United States. Like spoonbills, they have unfeathered heads and feed by touch in shallow water. To hunt, they lower the bill into the water and snap it shut upon sensing prey (mostly fish); their reaction time can be remarkably fast, with Wood Stork measured at 0.03 seconds. Like other wading birds, storks sometimes appear far out of range in summer and fall; some will remain for weeks in an area, especially where drying ponds concentrate fish.
6 species: Widely distributed in saline desert areas of the world.
These slender, long-legged, long-necked birds feed on aquatic microorganisms, filtering them with a particularly modified bill. All species have some pink in their plumage.
The United States has very few wild flamingos, at most a few dozen in Florida's Everglades, but flamingos may turn up in southern states, both escapees from captivity (and these include other species such as Lesser, Chilean, and Greater Flamingos) and wild wanderers from their West Indian range. Flamingos have highly specialized, angular bills with lamellae, or filters, that allow them to sift through mud and water to feed on tiny insects, crustaceans, algae, and other food. They usually forage by lowering the bill into shallow water while standing, although their webbed feet also make them good swimmers. Flamingos display in tight groups, turning their bills back and forth, stretching their legs, and raising their wings to reveal black remiges. Their nests are muddy mounds built on the ground.
15 species: Fairly widespread, but absent in South America. Two species breed in North America. One, the nearly extinct Whooping Crane, is strictly protected; the other, the Sandhill Crane, is more numerous and has a fairly wide range.
Cranes superficially resemble herons but are not related to them. Unlike herons cranes fly with the neck outstretched and with the upstroke faster than the down stroke. They are among the tallest birds in the world and inhabit open country, where they nest on the ground and lay only two eggs. Their colors run to black, white, and gray; most of them have a bare patch on the head.
Cranes have inspired humans for millennia with their extraordinary courtship displays: they perform exuberant dances that involve leaps, bows, dips, and wing movements and are accompanied by rolling, bugling cries. Cranes forage by walking slowly with the bill near the ground and pecking and probing for a variety of prey and vegetable material. They nest solitarily, often in large territories in bogs or marshes. Young cranes stay with their parents through their first winter and spring, learning migration routes and foraging techniques.
1 species: Restricted to tropical America, and breeding as far north as southern Georgia.
This is a swamp-loving, secretive, rail-like bird. It feed exclusively on aquatic snails, which it extracts without breaking the shell. It lays up to eight eggs in a nest in reeds.
A Limpkin might be mistaken for a bittern or young night-heron, but its decurved bill is a clue that it is related to rails. A closer look at the bill--with its right-hand curve and a twist at the mandible tip--reveals its specialized purpose: to extract the aquatic apple snail, the mainstay of this species' diet, from its shell. Nesting Limpkins tend to defend territories, as rails do, but they sometimes form loose "colonies." Limpkins wander northward on rare occasions, possibly in response to drought.
"Wading birds," as the term is used in this program, are long-legged waterbirds of six families: herons, nightherons, egrets, and bitterns (Ardeidae); ibises and spoonbills (Threskiornithidae); storks (Ciconiidae); flamingos (Phoenicopteridae); cranes (Gruidae); and Limpkin (Aramidae). The first three families are placed in the order Ciconiiformes, which also includes the vultures of the Americas. The others are only distant relatives of herons and their allies: cranes and Limpkin are in the order Gruiformes, which also includes the much smaller rails; flamingos are usually placed in their own order, Phoenicopteriformes. Most wading birds live in wetlands, from mudflats to marshes to swamps. They are largely carnivorous, eating aquatic vertebrates and invertebrates, although cranes also include acorns, fruit, and grains in their diet. Some species are highly specialized in their prey selection or foraging methods; others prey on a variety of animals using diverse techniques.
Most ardeid populations are relatively stable, but other wading birds have not recovered from past losses, particularly Whooping Crane and Wood Stork, whose numbers plummeted by 90 percent in the last century.
130 species: Worldwide. Nine species breed in North America.
|Corn Crake is a Eurasian rail species recorded 27 times in eastern North America as of 2005.|
The family Rallidae is represented in North America by six breeding species of rail (including Sora) and by one species each of gallinule, moorhen, swamphen, and coot. These small to medium sized birds somewhat resemble chickens, having rotund bodies, chicken-like feet, and a strutting gait, but they are most closely related to cranes and Limpkin and are classed with them in the order Gruiformes. Rallids are generally secretive, retiring birds with complex plumage patterns that make them difficult to see in the dense marshes most inhabit; the species that tend to forage more often in the open--such as American Coot, Purple Gallinule, and Common Moorhen--lack such cryptic coloration. In structure, rails may appear plump, but they are able to compress their bodies laterally and thus run quickly through dense vegetation. All rallids swim well; coots have specialized lobed toes with flanges that help them swim and dive nearly as well as a duck, and they are the only North American rallid species apt to be found in flocks like ducks. Purple Gallinule and the introduced Purple Swamphen have exceedingly long toes that enable them to walk on floating vegetation.
Rails and their relatives forage in aquatic habitats by picking and probing for small invertebrates and vertebrates; most species also incorporate plant matter in their diet. Like the smaller rails (often referred to as "crakes"), coots and moorhens have short, blunt bills best suited for picking up small prey or taking seeds and aquatic vegetation; the longer-billed species are better at probing into mud for small crabs or similar prey.
In courtship, the males of most rallid species strut and show off wings, flank patterns, and under-tail coverts to the females. While courting rallids are seldom observed, they are quite often heard. Their calls serve to keep a pair in touch with one another and to maintain territories. Nests are constructed of plant material and are usually well hidden within a marsh. Rail chicks are semi-precocial and are usually blackish (and thus confused with adult Black Rails on occasion). They follow their parents until they fledge, roosting at night in the nest in which they were hatched or in a nursery nest constructed by the parents. After breeding, most rallids in temperate areas migrate southward for the winter. Some are hunted as game birds.
When seen flushing from a marsh, a rallid may seem to have hectic, sloppy wing beats that barely keep it airborne before it drops back into the vegetation. This impression is misleading: rallids are very strong fliers, and they have colonized remote oceanic islands reached by few other birds. Their strong flight makes them capable of remarkable feats of vagrancy; several species that have been recorded extralimitally in the United States and Canada include Spotted Rail and Paintbilled Crake from the American tropics and Eurasian Coot, Baillon's Crake, and Corn Crake from Eurasia.
Although most rallid populations appear stable, Black Rail and King Rail have small, declining populations. The reasons for these declines are not well known.
The "gallinaceous" (chicken-like) birds in the order Galliformes are represented in North America by three families.
In the family Odontophoridae are the quail, including Northern Bobwhite. Phasianidae contains grouse, sage-grouse, prairiechickens, ptarmigan, and Wild Turkey, as well as the introduced Old World pheasants, peafowl, partridges (including Chukar), guineafowl, and Himalayan Snowcock. The tropical American family Cracidae has just one species in the United States, Plain Chachalaca, whose range barely crosses the border into southernmost Texas.
|Greater Sage-Grouse in flight, showing the rounded wing shape of gallinaceous birds.|
Galliforms are largely ground-dwelling birds that peck at the ground for food much in the manner of chickens. Most are compact and sturdy, with strong feet for walking and scraping the ground; some have long tails, but most are short-tailed and short-legged. Although galliforms are capable of flight, most run rather than flush. Plain Chachalaca is a talented tree climber and has a long hind toe adapted for arboreal life.
All natural habitats in North America-- including forests, fields, prairies, tundra, and bare mountaintops--are home to one or more species of chicken-like birds. Scaled and Gambel's Quail thrive in the arid Mojave, Sonoran, and Chihuahuan Deserts, where temperatures over 115deg F (46deg C) are not rare, and Rock Ptarmigan is a permanent resident in northern Nunavut, where temperatures can drop as low as -60deg F (-51deg C). Each species is well suited to its environment; ptarmigan, for example, have thick, insulating plumage, including feathered legs and feet, while desert-dwelling quail conserve water in their organs with remarkable efficiency. Galliforms feed mostly on plant matter, especially seeds and buds, and also eat insects and other invertebrates.
Galliforms are sexually dimorphic in plumage. The more highly ornamented males possess, depending on the species, eye combs, wattles, air sacs on the neck, "beards" of feathers on the breast, pinnae (feathers that look like rabbit ears when raised), crests, and topknots. Males flaunt, raise, or inflate their adornments during elaborate, cacophonous courtship displays. Most galliforms build nests in concealed places on the ground; cracids nest in trees. Chicks are precocial and forage for themselves just after hatching.
Many populations of galliforms are declining rapidly, not so much from hunting losses (many are game birds) as from destruction or alteration of their habitats. Several species have lost well over 99 percent of their pre-colonial populations and continue to decline, especially the sage-grouse, prairie-chickens, and Northern Bobwhite.
Exotic Game Birds:
Dozens of species of game birds and "ornamental" birds in the order Galliformes have been imported to North America. Of those species released into the wild, Chukar, Gray Partridge, and Ring-necked Pheasant have established thriving populations here; such factors as inhospitable climate, predators, diseases, and over hunting have prevented others from becoming widely established. Nevertheless, many species of exotic galliforms are observed in North America after they escape (or wander off) from captivity or are released for hunting purposes.
Some of the gallinaceous birds introduced in North America differ markedly from their wild counterparts in the Old World. Ring-necked Pheasant is native to Asia, but most that breed in North America are descendants of birds produced in captive crossbreeding programs in the 19th century in England that involved different subspecies (mostly those known as "Blackneck" and "Chinese Ringneck"). Every year new Ring-necked Pheasants are released in North America for hunting; these released birds can show much variation in plumage. Green Pheasant (Phasianus versicolor) of Japan, which has mostly dark green body plumage and was once considered a subspecies of Ring-necked, is occasionally released for hunting but no longer breeds in North America.
|Common Peafowl (Pavo cristatus), called "peacock" by most people, is a southern Asian species uncommon in the wild but frequently observed on farms, parklands, and estates worldwide. Females are much plainer than the stunning males and lack the enormous tail.|
|Helmeted Guineafowl (Numida meleagris), native to Africa, is prized less for its appearance than for its habit of eating ticks. Feral guineafowl are known to breed in the wild in the southern United States and appear not to be dependent upon humans for food in some areas.|
|Red-legged Partridge (Alectoris rufa), a native of western Europe, is similar to Chukar but smaller. The species has no self-sustaining population in North America; it is bred in captivity, both for food and to release for hunting.|
|The tiny Japanese Quail (Coturnix japonica), smaller than Northern Bobwhite, is also occasionally released, though less so now than in the past. It might be confused with a small rail or the young of larger galliforms.|
189 species: Worldwide except Australian region.
This large and varied family contains almost all the birds that resemble chickens. They have stocky bodies; thick, short legs; large toes that are adapted for walking and scratching; and short, blunt bills that are well suited for crushing seeds and feeding on a variety of insects and other small creatures. In North America these birds can be divided into four groups: the introduced pheasants and partridges; the grouse, which have feathered legs and feet; the turkeys; and the native quail, of which the Northern Bobwhite is the most widespread.
50 species: Tropical and subtropical regions of the Western Hemisphere. One species occurs as far north as the Rio Grande Valley in Texas.
These large, long-legged, long-tailed, chicken-like birds spend much time in trees, where they run nimbly along branches, searching for the buds and tender new leaves that are an important part of their diet.
The family Pandionidae contains only a single species, the Osprey (Pandion haliaetus).
Until recently, the Osprey was classified in the same family as the hawks and eagles, but recent research has shown that it should be placed in a distinct, although related, family. The Osprey is a specialized predator whose diet is composed almost entirely of fish.Ospreys are found throughout the world, on every continent except Antarctica, wherever there are fish populations it can feed on. They hunt by hovering over a body of water, spotting a shallow-swimming fish with their acute eyesight, then diving powerfully and pulling the fish from the water in their talons. Occasionally, a Bald Eagle will approach an Osprey in midair as it flies back to a perch with its catch. The larger eagle can frighten the Osprey into dropping the fish, which the eagle then steals.
The Osprey was one of the bird species most severely affected by DDT poisoning, but has experienced a remarkable recovery in North America since DDT was banned in the 1970s. Ospreys nest on trees or any other tall object near a body of water where they can feed, and have shown great adaptability to artificial. nesting surfaces, sometimes endangering their own lives as well as causing power outages when they nest on power poles and accidentally contact the transformer. In some areas purpose-built Osprey nest platforms have been constructed on separate poles, keeping the birds off the power poles.
|Red-tailed Hawk, like other diurnal raptors, tears its prey into small pieces before eating.|
239 species: Worldwide. Twenty-one species breed in North America.
Thirty-two species of diurnal raptors--including hawks, eagles, kitesand Northern Harrier, (family Accipitridae), Osprey (Pandionidae) and falcons and Crested Caracara (Falconidae)--nest in North America, and another eight species have been reported as vagrants from Mexico or Eurasia. Diurnal raptors, usually recognized by casual observers as hawks or eagles, are birds of prey with hooked bills and talons adapted for killing prey and tearing into flesh. (Owls are also birds of prey, but most owls hunt nocturnally.) Their speed and skill when hunting have been a source of wonder for humans since our earliest written history. Some species of diurnal raptors supplement their diet with carrion, especially under adverse conditions or when prey is scarce.
Members of the family Accipitridae, often called accipitrids, range greatly in size--from the tiny Sharp--shinned Hawk, with a wingspan of less than (50cm), to the mighty Steller's Sea-Eagle (a vagrant in North America), the world's largest eagle, with an 88in (2.5m) wingspan. Because accipitrids have evolved to exploit different prey resources, they differ greatly in shape as well as size. Harriers and White--tailed Kite have elegant, long wings and tails, perfect for coursing over meadows and marshes in search of rodents; the similarly shaped but more aerial Mississippi and Swallow-tailed Kites hunt dragonflies in midair. The Hook-billed Kite, which feeds mostly on arboreal snails, also has a distinctive paddle-shaped wings adapted for its specialized foraging strategy.
The three accipiters (genus Accipiter) are relatively long-tailed like kites, but they have broader, shorter wings better adapted for hunting in closed environments such as thickets and forests, where they pursue mostly birds. The buteos (genus Buteo) and their relatives in the Southwest (Common Black-Hawk, Harris's Hawk) all have broad wings and relatively short tails for harnessing warm, rising air (thermals). With little effort, these birds can remain aloft most of the day as they watch for prey on the ground; their vision is up to eight times more acute than a human's. Most buteos also hunt well from perches, such as fence posts, treetops, or cliffs.
The three accipiters (genus Accipiter) are relatively long-tailed like kites, but they have broader, shorter wings better adapted for hunting in closed environments such as thickets and forests, where they pursue mostly birds. The buteos (genus Buteo) and their relatives in the Southwest (Common Black--Hawk, Harris's Hawk) all have broad wings and relatively short tails for harnessing warm, rising air (thermals). With little effort, these birds can remain aloft most of the day as they watch for prey on the ground; their vision is up to eight times more acute than a human's. Most buteos also hunt well from perches, such as fence posts, treetops, or cliffs.
Courtship among diurnal raptors involves paired flights above a territory; male buteos, Golden Eagles, and accipiters also perform display flights that consist of exaggerated, slow wing beats or abrupt, swooping dives. These aerial acrobatics also serve as warnings to other members of the species not to pass through the nesting territory. All accipitrids build nests of vegetation, usually twigs and sticks. Larger falcons nest on bare cliffs or ledges and smaller falcons nest in cavities (American Kestrel) or old nests of crows, ravens, or other raptors (Aplomado Falcon and Merlin). Vultures and condors usually nest in caves or cliff recesses. Most diurnal raptors migrate southward in winter or make some sort of movement away from the nesting area after breeding, especially when prey becomes scarce.
Because raptors are "apex predators" (at the top of their food chain) that feed largely on vertebrates, they have been subject to repeated poisoning in modern times: pesticides such as DDT become increasingly concentrated in fish and other prey items as they work their way up the food chain, and their levels reach lethal proportions in the top predators. Peregrine Falcon, Osprey and Bald Eagle were threatened with extinction by the early 1970s, due to eggshell thinning and premature hatching caused by DDT. Local reintroductions and efforts by conservationists to ban DDT and other organochlorine pesticides in North America have brought these and other species back from the brink of extinction.
63 species: Worldwide. Seven species breed in North America.
|Peregrine Falcons take mostly avian prey in dazzling, high-speed dives (or "stoops"), often from high in the air.|
This family includes true falcons (genus Falco) and also the caracaras, which are larger and often feed on carrion, as vultures do. True falcons have long pointed wings and long tails, and are among the fastest flying birds in the world. They mainly inhabit open country and many pursue birds on the wing. Unlike other birds of prey, true falcons do not build nests of their own but utilize other birds' nests or lay eggs in hollow trees, on cliffs or on the ground.
Falcons are renowned for their speed and grace in the air, which many feel are unrivaled in the world of birds. True falcons range in size from the petite American Kestrel to the stocky Gyrfalcon, but all are somewhat similar in shape. Their long, pointed wings and moderately long tails are adapted for rapid acceleration and maximum maneuverability when pursuing prey, whether aerial insects, shorebirds, or ptarmigan. Crested Caracara, a distinctively patterned relative of falcons, is quite different in shape, its long legs and heavy, deep bill suited for flexible foraging strategies that include walking on the ground to scavenge carrion. Caracaras build nests like other birds of prey.
7 species: Tropical and temperate America. Three species, including the nearly extinct California condor, breed in North America.
California Condor and the two vultures found north of Mexico (Cantharides) are often considered "honorary raptors," as they forage and migrate in the skies much like raptors; however, their evolutionary relationships with raptors are unclear and they seldom take live prey. These scavengers feed on carrion and refuse. Their claws are blunt instead of sharp talons like those of hawks. Vultures are large, mostly blackish birds with broad wings and bare heads; their naked heads prevent their feathers from becoming fouled while they feed on carrion. They nest in tree cavities or on the ground.
Like caracaras, vultures and condors have strong legs and bills for gaining access to carcasses of dead animals, which form almost their entire diet. Their naked heads are an adaptation for feeding on carrion, which can quickly soil feathers and spread disease. Turkey Vulture is known to have such keen senses of smell and vision that Black Vultures appear to follow them to dead animals.
Identifying Raptors in Flight:
Raptors and vultures in flight challenge birders to become proficient at identification from afar. Shape, flight style, and plumage characteristics are often evident enough to distinguish species, even at great distances, especially among the very large birds and the very small. The raptors intermediate in size between the smallest and the largest, however, require careful study. The six species described below can be confused with each other in various ways, even though they are not all closely related.
Raptors in Flight
|Peregrine Falcon's long, pointed wings often jut forward at the wrist, for a crossbow silhouette. Peregrine has a shorter tail than Mississippi Kite, and its fleet, fluid wing strokes are unlike the more delicate, buoyant actions of the kite.|
|Mississippi Kite has long, pointed wings and a slender body. Despite its smaller size it can resemble a Peregrine Falcon when seen at a distance or in silhouette, but unlike falcons, kites twist and fan the long tail often when foraging.|
|Prairie Falcon is regularly mistaken for Peregrine over the continent's western interior. Prairie differs in its small size and its shape: it is more evenly slender of body and less pointed in the primary region (the outer portion of the wings).|
|Gyrfalcon, despite its larger size, is also sometimes taken for a Peregrine; it has much broader wings overall, and its wingtips often look barely pointed. With its very heavy body and broad tail it can resemble a soaring buteo.|
|A soaring juvenile Northern Goshawk can be confused with an immature Red-shouldered Hawk: both have a long, broad, banded tail, rather long, full, tapered wings with a slight bulge in the secondaries, and streaky under parts.|
|Red-shouldered Hawk juvenile is distinguished by the pale crescents at the base of the primaries. Compared to Northern Goshawk, its wingtips are more square-cut and less tapered, its wings are fuller, and its tail is not as long.|
Buteos exhibit many differences related to subspecies, morph, and age. Given the extreme variation in plumage in species such as Red-tailed Hawk, it is wise to learn the basic shapes of the various buteos. In the species shown below, soaring adults (illustrated) have shorter tails and rather shorter, broader wings than immatures, and the difference in shape between adults and immatures can be substantial. Buteos can change flight behaviors rapidly, altering the appearance of the wing shape.
|Red-tailed Hawk has full, wide wings and a broad tail. In soar, its wings usually show a bulge through the secondaries; the wings of other buteos seldom impart such an impression of breadth.|
|Ferruginous Hawk is large-bodied, like Redtailed, but its wings lack the bulging secondaries and appear longer overall, more tapered, and pointed in the "hand." Ferruginous usually does not fan the tail broadly; Red-tailed often does.|
|Rough-legged Hawk can recall a slender version of Ferruginous (and both species have a dark morph), but its tail and wings appear longer, more graceful, and less broad in the "arm" (a hawk watcher's term for the wing's inner portion).|
|Swainson's Hawk looks longer-tailed and more slender-winged than other buteos, especially as an immature. In full soar, the wings appear to curve gently along the trailing edge to a neat point that is accentuated by the dark remiges.|
|Red-shouldered Hawk can look somewhat lanky in the wing when immature, but adults look full-winged, and their wings have more gently rounded trailing edges than the wings of the larger and bulkier Red-tailed.|
|Broad-winged Hawk is a relatively small buteo with proportionately wider wings that come to a broad point in the outer primaries. A soaring Broad-winged, with tail and wings fully spread, has a compact shape all its own.|
North American accipiters--Sharp-shinned Hawk, Cooper's Hawk, and Northern Goshawk can be tricky to identify while on the wing. Size can be unreliable, because it is difficult to judge the size of birds in the air, especially among species exhibiting such pronounced sexual dimorphism in size (for example, female Sharp-shinned Hawk is nearly as large as male Cooper's Hawk). Hawkwatchers concentrate on four aspects of flying birds: tail, wings, head, and belly.
The tails of the three species are all relatively long, but they are differently shaped and patterned. Sharp-shinned Hawk has the shortest tail of the three, with a squared end that often shows a central notch. Cooper's Hawk has a long, narrow tail by comparison, usually with a broad, rounded end that shows a fairly wide pale terminal band. Northern Goshawk's tail appears shorter and broad by comparison and has four dark zigzag bands when seen from above (the others have three bands). There are exceptions, including some Sharp-shinneds with rounded tails and rare Cooper's with squared tails.
The wings of accipiters differ as well: Sharp-shinned and Northern Goshawk have rather broad or full-looking wings for their sizes, with a sinuous S-curve along the trailing edge, while Cooper's Hawk has narrower, lanky-looking wings that taper more gradually toward the tip. Sharp-shinned flaps its wings quickly, Cooper's employs slower and more graceful wingbeats, and Northern Goshawk uses deep and impressively slow strokes.
Sharp-shinned's head looks quite small and neckless, with eyes set in the middle. Cooper's Hawk has a large, long, and flexible head, with eyes set farther forward (and unlike the other accipiters, immature Cooper's tends to have a tawny nape). Northern Goshawk's stout head recalls a buteo's.
The belly is an important identifying feature of immature birds: Cooper's has a very pale, almost unmarked lower belly, while Northern Goshawk and Sharp-shinned are heavily marked from the breast well into the belly.
90 species: Worldwide. Thirty-six species breed in North America.
The members of this family that frequent our waters range in size from the large Long-billed Curlew to one of the smallest, the Least Sandpiper. They are wading birds that are found on seacoasts and on inland lakes and rivers, and most of them nest on the Arctic tundra. Many perform tremendous migrations to the Southern Hemisphere in autumn and back north again in the spring. This family includes curlews, godwits, snipes , woodcocks, turnstones, phalaropes, dowitchers, yellow-legs, and the "peeps"- the smallest sandpipers of the genus Calidris.
60 species: Worldwide. Nine species breed in North America.
Plovers are small to medium-sized shorebirds with short bills slightly swollen at the tip. These birds run along the sand or mud for a way, suddenly stop and probed for food in the soft ooze, and snatch worms, snails, small crustaceans, and insects from the ground. Most of the species have characteristic black or brown breast bands on white background.
7 species: Widespread in warm regions. Two species breed in North America.
Oystercatchers are large and boldly patterned in black or in black and white, with reddish bills and legs. They inhabit seacoasts and, less often, inland rivers, where they feed on shellfish, crustaceans, and sandworms. They are conspicuous birds whether feeding on mud banks or nesting in the sand, where they lay from two to five eggs.
7 species: Fairly widespread in warmer regions. Two species breed in North America.
Avocets and stilts are flashy shorebirds with vivid patterns of black, white, tan and pink. Both are long-legged and long-necked; the long bills are upturned in avocets, straight in stilts. Avocets have partially webbed feet, presumably as an aid in swimming in deeper water than most waders attempt.
8 species: Worldwide in the tropics. One species is an occasional breeder in North America.
Jacanas have very long toes and claws, and are adapted for walking on lily pads and other floating marsh vegetation. They are aggressive birds, several species being armed with spurs with which they defend their territories. In their exposed habitat, they have no need for cryptic coloration; most species are boldly patterned, and several have brilliantly colored frontal shields.
Shorebirds are closely related birds of open-country and shoreline habitats. The largest family, the sandpipers, includes sandpipers (the smallest of these are called "peeps"), yellowlegs, redshanks, greenshanks, curlews, dowitchers, phalaropes, snipe, woodcocks, tattlers, godwits, turnstones, stints, knots, Willet, Whimbrel, Sanderling, Dunlin, Ruff, and Surfbird. Of some 75 species recorded in North America, 36 are known to have bred on the continent; one, Eskimo Curlew, is likely extinct.
Sandpipers show extraordinary diversity in size and shape. They are usually brown, white, and rust, although some are more dapper. In phalaropes, females are more brightly colored than males, a reverse sexual dimorphism that is rare among birds; the more cryptically plumaged males incubate the eggs and tend the young. Sandpipers rely on touch and smell when foraging. The smaller species pick around in open habitats for tiny invertebrate prey, while larger species probe more deeply into mud or sand to extract much larger prey. Many shorebird species feed near one another on mudflats or pond margins. Phalaropes often forage on lakes and ponds by spinning in circles to create a vortex that brings tiny prey items to the surface.
The other large shorebird family, Charadriidae, contains plovers and lapwings; 16 species have been recorded in North America, and 11 species breed regularly here. As a rule, plovers have shorter, thicker bills than similarly sized sandpipers, and they tend to forage more in the manner of American Robins: running for short distances, then pausing, looking, and listening before extracting small invertebrate prey from the substrate.
Several smaller families of shorebirds have bodies and bills adapted for more specialized foraging. The oystercatchers (Haematopodidae) are husky birds with powerful bills designed to crack open mollusks. They are found almost exclusively on outer coasts, where their prey is readily available. The stilts and avocets (Recurvirostridae) are elegant, long-legged shorebirds with striking plumages and slender bills; the upwardly curved bills of avocets are adapted for sweeping insect larvae and other small organisms from the water. Northern Jacana, in the tropical family Jacanidae, has extremely long toes, similar to a gallinule's, and can walk on floating vegetation.
Shorebird courtship displays involve rhythmic calling, posturing and parading on the ground, and sometimes aerial activity such as flying in circles while calling (as in woodcocks) or diving earthward (as in snipe). Most shorebirds are monogamous, although phalaropes practice polyandry (females have multiple mates), and several species are polygynous (males have multiple mates).
The conservation status of most shorebirds is complex and in many cases poorly known. Species with small populations are of great concern, but documented declines in more numerous species such as Semipalmated Sandpiper, Red Knot, Sanderling, and Whimbrel have raised red flags in recent years.
Identification of Shorebirds:
|Western Sandpiper, dull juvenile||Western Sandpiper, juvenile|
Identification of shorebirds can be quite complicated. Among the factors to consider are time of year, habitat and location, and molt. Shorebirds can display extensive variation within a species, particularly among juveniles and molting birds. Spotting scopes aid in obtaining detailed views of the birds' plumage and structure, which is usually necessary for identification.
Timing and Location:
Most shorebirds that nest in Alaska and Canada begin their southward migration toward stopover and wintering grounds soon after nesting, as early as the third week of June. Adults leave the nesting areas earlier than juveniles (young of that year), and from late June through much of July most of the shorebirds seen on mudflats in the lower 48 states are adults.
By late July juveniles of several species begin to appear in the flocks, and by the middle of August they usually predominate. In late summer to autumn, it is easy to distinguish between adult and juvenal plumages of most shorebirds: adults show worn, splotchy-looking feathers, especially in the coverts and tertials; juveniles show uniformly fresh coverts and remiges that often have crisp, pale borders, giving them a neatly spangled, scalloped, or scaly appearance above. In autumn juveniles, if not recognized as such, can be mistaken for adults of another species.
Plumages and Molt:
Molt in shorebirds is similar to molt in their nearest relatives, the terns and gulls. Adults molt twice per year, between brighter breeding plumage and duller non-breeding plumage (also called alternate and basic plumages, respectively). Molting birds exhibit transitional plumages, in which aspects of different plumages are apparent.
Over a period that can extend from January into April, adults attain breeding plumage through a partial molt of body, head, and some covert feathers, and make their northward migration to breeding grounds. Their complete molt (all feathers) into non-breeding dress occurs just after breeding, usually August into November, along with the migration southward to staging and wintering sites.
Juveniles begin a partial molt of head and body feathers into their first-winter plumage soon after they reach staging areas on the coast (midsummer into the autumn months).
By spring, adults have molted into breeding plumage again and returned northward to nesting areas. In some species, first-winter birds do not migrate to the breeding grounds with adults but stay in wintering areas. There they undergo a partial molt into first-summer plumage; this plumage varies among species and individuals: it can look very much like first-winter plumage or nearly as bright as adult breeding plumage. (The subadult first-winter and first-summer plumages are not illustrated in this guide.)
Molts are protracted and differ among species: some molt on migration, others afterward, others both during and afterward. Adult Long-billed Dowitchers, for example, appear to undergo a complete molt at stopover sites in the interior of the continent before moving to coastal wintering areas. Adult Shortbilled Dowitchers do not begin to molt their flight feathers until they reach coastal wintering areas. Thus a dowitcher in wing molt seen away from the coast is almost certainly a Long-billed.
310 species: Worldwide.
Pigeons and doves (family Columbidae) are represented in North America by 12 breeding species, three of which are not native, and six vagrants from Eurasia or tropical America.
Most columbids are medium-sized, stocky birds with small heads, short, thin bills, medium-long tails, and short legs. The grounddoves and Inca Dove (genus Columbina) are much smaller birds than those in the genera Patagioenas (Band-tailed, Red-billed, and Whitecrowned Pigeons), Zenaida (Mourning and White-winged Doves), Columba (the introduced Rock Pigeon), Streptopelia (the introduced Eurasian Collared-Dove and Spotted Dove), and Leptotila (Whitetipped Dove). Quail-doves, in the tropical American genus Geotrygon, are very plump-looking, terrestrial doves that resemble quail; two species are very rare vagrants in the United States.
Most North American columbids have rather plain plumage that is countershaded gray or brown above and paler below. The very dark tropical Red-billed and White-crowned Pigeons are exceptions, and many species have pink or green tints or iridescent colors in the nape. Rock Pigeons, those urban dwellers known to most people as simply "pigeons," show a wide variety of plumage types that are derived from many centuries of captive breeding. Many individuals seen in North America, however, exhibit the species' ancestral phenotype--that is, the way wild Rock Pigeons still look today on the cliffs of Scotland. "Ringed Turtle-Dove," which also shows plumage variation, is not a true species: it was bred by aviculturalists (people who raise and breed captive birds) from doves of the genus Streptopelia.
Pigeons and doves are found mostly in open habitats, from deserts to prairies to city parks; a few thrive in forested habitats. They forage on the ground and in trees for seeds, fruits, and nuts. Perhaps because of their high-fiber diet, most species consume large amounts of water; they drink by siphoning, as through a straw, continuously (other birds dip the bill and let gravity deliver the water to the stomach).
In the United States, columbids court and breed through much of the year, and courting males are easy to observe as they strut, bow, coo, and make display flights over the nesting area. All species build sloppy-looking stick nests in trees or bushes in which they lay just one or two eggs. After the breeding season, some species gather in rather large flocks, and at least four species are migratory-- Mourning and White-winged Doves and White-crowned and Band-tailed Pigeons.
One native species, Passenger Pigeon, became extinct in the early 20th century. Once possibly the most abundant bird species on the planet, Passenger Pigeon was hunted to extinction by European settlers in the New World; the last individual died in 1914 in the Cincinnati Zoo at age 29.
The larger pigeons and doves are considered game birds and are hunted in the non-breeding season. Passenger Pigeon became extinct at least in part because of excessive hunting. This pigeon may once have been one of the world's most numerous bird species, its population estimated in the billions well into the early 19th century, when flocks were said to "darken the skies." No North American columbid is currently considered endangered, although population declines in Common Ground-Dove and Bandtailed Pigeon in some areas are of concern to conservationists.
Parrots and parakeets (and macaws) are members of the family Psittacidae, which includes about 360 species worldwide.
While psittacids vary in body shape--from the slender, long-tailed parakeets to the stout-bodied, short-tailed parrots--all have strong, curved maxillas for opening fruits, seeds, and nuts. They typically are highly social, nest in cavities, and have loud, far-carrying calls. Most New World species have green plumages with other colors in the wings and head. The only native representative from temperate North America, Carolina Parakeet, is now extinct. A few Mexican species have been detected in border areas: Thick-billed Parrot was formerly resident in Arizona (it is now confined to the highlands of Mexico), and at least some of the Red-crowned Parrots and Green Parakeets that nest in southernmost Texas are probably of wild provenance.
|Once common in the Southeast, Carolina Parakeet has been extinct since about 1940.|
The southern United States is home to many exotic psittacids (more than 90 species recorded), nearly all of which are escapees from pet owners. Many Amazona species are resident nesters in Florida and California, and the striking Black-hooded Parakeet nests locally in Florida. Chestnut-fronted Macaw now nests in Florida. In addition to these Neotropical species, psittacids from Africa and Australasia, such as Budgerigar, Cockatiel, and various lovebirds and cockatoos, are also often observed. North America lacks the natural habitats in which most exotic psittacids evolved, and the birds depend on urban and suburban environments to provide their food--mostly from exotic fruit and nut trees--and nesting and roosting areas. Unlike the tropical species, Monk Parakeets are adapted to living in temperate climates and can be observed year-round in many large cities, even as far north as Chicago.
Because they are found mainly in developed environments, parrots and parakeets tend not to displace native birds from their niches, as some other introduced birds have done (European Starling, for instance). Conservationists, however, are concerned about the potential spread of avian diseases by parrots to native birds and about the very real damage to native populations of parrots posed by the caged bird trade. Many species of psittacids worldwide have become endangered, and several even extinct, because of this trade.
143 species: Worldwide. Six species breed in North America.
Cuckoos, anis, and roadrunners are members of the family Cuculidae, an ancient group of birds with no close relatives among other bird families. Cuculids are long-tailed, medium-sized birds; with their relatively short legs and zygodactyl feet (two toes point forward, two backward), they are best suited for perching, though Greater Roadrunner is terrestrial. Most cuculids are found in warmer climes, even in deserts; Black-billed Cuckoo ranges well north into Canada to the edge of the boreal forest. In addition to the six regular nesting species found in North America, Oriental and Common Cuckoos (of Eurasia) have occasionally turned up on Alaskan islands.
In plumage, cuculids show remarkable diversity, from the coal black simplicity of the anis, to the countershaded plumage and patterned tails of cuckoos, to the streaky camouflage of roadrunners. They generally have curved, short bills, although the bills of anis are very deep and those of roadrunners are rather long. Their bills suit their diets well: cuckoos forage on caterpillars, including large, hairy caterpillars few other birds eat; anis eat a wide variety of seeds, fruits, insects, and reptiles; and roadrunners take prey as large as adult rattlesnakes, kangaroo rats, and sparrows. Anis and cuckoos are stolid foragers, peering around slowly while perched and then making a swift sally out to snare prey. Roadrunners are sometimes stealthy when hunting but also use direct pursuit; when running down lizards they can achieve speeds of up to 25 miles per hour (40km/hr). Roadrunners sometimes capture prey by teamwork; for example, when confronting a poisonous snake, one bird distracts the snake while the other strikes. When taking live prey, cuculids tend to dispatch the prey and then soften it by beating it against a branch or, in the case of roadrunners, a stone.
Courtship among cuculids is a rather simple affair, with the male calling and chasing the female and offering food, which is often exchanged during copulation. All species make sloppy-looking stick nests similar to those of doves, and their young hatch asynchronously, like those of owls. North American cuculids tend to rear their own young (some Old World species are brood parasites); even on the rare occasions when they lay their eggs in the nest of another bird species, they feed all the nestlings, along with the host parents.
Anis sometimes nest communally, and the young remain with their parents for at least six months after hatching, working as nest helpers to feed the next brood. Cuckoos are long-distance migrants to Central and South America. Anis move much shorter distances: Groove-billed Ani repairs into Mexico, while Smooth-billed Ani is mostly sedentary in Florida.
The conservation status of the cuckoos is difficult to assess, as they wander widely in search of local outbreaks of tent caterpillars, their preferred prey. In the desert Southwest, Yellow-billed Cuckoo is tied to riparian corridors and is very scarce. Smooth-billed Ani was once common and widespread in Florida but is now found only sparingly in the southeastern part of the state.
161 species: Worldwide. Eighteen species breed in North America.
Members of this well-known family range from the huge Great Horned and Great Gray owls to the diminutive Elf Owl of the arid Southwest. Nearly all of the species are nocturnal, but some, such as the beautiful Snowy Owl of he Arctic, also hunt in the daytime. Owls do not build their own nests but use abandoned nests of other birds, such as stick nests in trees. They also nest in hollow trees, and more rarely, on cliffs or on the ground. All species lay with eggs. During the cold months, many of these birds roost in dense evergreens. Although, like hawks, they have sharp talons and hooked beaks for killing their prey, they are not related to hawks.
17 species: Worldwide. Only one species, the Barn Owl, occurs in North America.
These long-legged, densely plumaged owls have conspicuous heart-shaped facial disks and dark eyes. They are found mostly in forests, but several species in the Old World tropics are adapted to open grasslands.
North American owls are placed in the families Strigidae (typical owls) and Tytonidae (barn owls); these two families are relatively closely related and have as their nearest of kin in North America the nightjars and nighthawks.
|Nocturnal owls use their keen hearing to locate prey, but diurnal species, such as this Northern Hawk Owl, hunt visually. Owls swallow prey whole.|
Owls vary greatly in size, but all have strong, hooked bills and talons (suited for capturing, killing, and eating live prey), eyes adapted for foraging at night, and broad, usually rounded wings. Ecologically, owls are rather like hawks: they are widespread and found in virtually every habitat, even heavily urbanized areas; the smallest species prey on large insects, the largest on small mammals; and their plumages are composed mostly of browns, rusts, black, and white.
Owls, however, have several morphological differences from hawks that are related to their nocturnal activities. They have a round facial disc that focuses sound waves to their very sensitive ear openings. The ear openings of some species, such as Great Gray Owl and Barn Owl, are strongly asymmetrical, which permits them to pinpoint the location of rodents tunneling under deep snow or hidden beneath grasses on moonless nights. Many species have "horns" (ear tufts) that, along with cryptic plumages, help camouflage them as they roost by day. Like hawks, owls have keen vision, but the eyes of most owls are specially adapted for gathering light in order to hunt at night. Night-hunting owls also have tiny serrations in the edges of the outer primaries, which make their flight almost inaudible. They hunt by stealth in flight, usually taking prey on the ground; many species are adroit hunters in thick cover, particularly those that eat birds, such as pygmy-owls.
Owls usually swallow prey items whole, later regurgitating a pellet of the bones, fur, and other indigestible parts.
Many owls time their breeding to coincide with peak abundance of prey. Larger species make bulky stick nests in trees or on cliffs (Barn Owl also nests in barns and other structures), while smaller owls nest in cavities. Some species take readily to nest boxes, which they also use for daytime roosting. Flammulated and Elf Owls are Neotropical migrants, and Barn and Short-eared Owls regularly leave northern parts of their breeding range; most species, however, are sedentary or irrupt southward in "flight years," mostly when prey is scarce in the breeding range.
Populations of many owls appear to be declining. Burrowing Owl, usually found in the West in prairie-dog towns or ground squirrel colonies, has suffered because of eradication of those rodents. Spotted Owls have been victims of habitat loss, especially of the heavily logged old-growth coniferous forests of the Pacific coast.
83 species: Worldwide. Eight species breed in North America.
Nighthawks and nightjars (family Caprimulgidae) are members of a large family found across the world in tropical and temperate regions. Most are familiar only in their voices, which ring out on spring evenings, or as a set of glowing orange-red eyes seen in the headlights on country roads at night. Their colloquial name, "goatsuckers," derives from the folk belief that some species drink the milk of goats.
Caprimulgids are medium sized, slender birds, usually with rather long wings and tails, short but very broad bills, and very short legs. Their plumages have complex patterns of dark browns, black, and white, which help them blend into their environment and escape detection by predators. Their cryptic coloration and nocturnal habits recall owls, which are their nearest relatives. Owls, however, have much larger, stronger feet and heavier bills, even those species that eat mostly flying insects, the chief food of caprimulgids.
Nighthawks (genus Chordeiles) are found only in the Americas; they differ from nightjars (most in Caprimulgidae) in having longer, more pointed wings that lack barring, paler bellies, and crepuscular feeding habits (they feed at dawn and dusk). They are often seen flying overhead in open habitats, even in cities, hawking insects much like a bat or swallow. Nighthawks are diurnal migrants and congregate in large flocks when migrating; nightjars are solitary, nocturnal migrants. Most capri mulgids winter in the tropics. With few exceptions, caprimulgids forage in flight. Nighthawks tend to fly higher than nightjars, coursing back and forth above treetop height and seizing insects with their wide gapes. Nightjars often perch-hunt, fluttering up from the ground or a horizontal tree limb upon spotting a moth or other insect. Nightjars have well-developed rictal bristles, stiff hair like feathers that probably serve a tactile function and help guide prey to the mouth.
|In conflict and courtship, caprimulgids (here Common Poorwill) often spread wings and tail, revealing contrast markings.|
The rarely seen courtship displays of nightjars consist of males spreading the tail and wings to reveal areas of white and often distending the white throat, while calling. Common Nighthawks are often observed in display: the male calls and dives suddenly from high in the air, pulling up into a large, U-shaped arc and making a loud wing noise at the bottom of the dive. All caprimulgids nest on the ground (or a flat rooftop, in the case of some Common Nighthawks), using a shallow scrape rather than building a nest.
Population trends in caprimulgids are poorly understood, but several sets of data indicate a widespread decline in Common Nighthawk and in Whip-poor-will.
94 species: Chiefly tropical regions in the Old World.
Kingfishers are heavyset birds with heavy bills and heads but small feet and short tails. Their structure reflects an adaptation for fishing, specifically for plunge-diving from a perch or a hovering position. North American species are blue or green above and white below, with a rufous breast or belly in all but the male Belted and female Green Kingfishers. They eat fish, aquatic crustaceans, and amphibians. Many tropical species also catch insects and lizards on land. Courtship consists of aerial chases and feeding. All North American species nest in burrows excavated in earthen banks where they lay their white eggs.
|Male Elegant Trogon at nest hole.|
39 species; Tropical areas of America, Asia, and Africa.
Trogons are long-tailed, medium sized birds with short legs and short, rather heavy bills. Plumage patterns of males and females are similar, although males are more brightly colored. When foraging, trogons and quetzals sit almost motionless, peering around slowly much like cuckoos. Upon spotting a large insect or small lizard, they fly swiftly to pluck it from a branch. Both trogons and quetzals also readily forage on berries; they nest in old woodpecker cavities. Populations of trogons and kingfishers in North America appear to be stable.
215 species: Widespread but absent from Australia, New Guinea and Madagascar. Twenty-two species breed in North America, and one, the Ivory-billed Woodpecker (campephilus principalis) may recently have became extinct.
|Female Pileated Woodpecker feeding young|
Woodpeckers (family Picidae) live wherever there are trees or large cacti. They specialize in foraging on trees, usually by removing bark or drilling holes to take insects and their larvae. Some species also eat acorns, which they may store in granary trees for later consumption. Woodpeckers have chisel-like bills suited to scaling bark or creating foraging pits in trees. They have strong feet, with toes usually in a zygodactyl arrangement (two toes pointing forward and two backward), and stiff tails to brace against as they cling to or hitch up trees in small vertical "leaps." Built to extract prey from tight spaces, woodpeckers' tongues are barbed and very long (up to 5"/13cm).
Most species use rapid-fire, loud drumming to mark territory and attract and keep in contact with mates. Many species also communicate with descending "fuss" or "whinny" calls. Woodpecker courtship is ostentatious: most species call rapidly, raise the crown feathers, spread the wings while clinging to a tree, and bob rhythmically together. All woodpeckers excavate cavities for nesting; some accept artificial cavities. Many species mate for life.
Red-cockaded and Ivory-billed Woodpeckers are endangered, the latter critically or possibly extinct. Other American woodpecker populations appear to be stable or have had only modest declines.
The majestic Ivory-billed Woodpecker (Campephilus principalis, L 19" (48 cm) W 33" (84 cm) was a relatively common resident of southeastern forests through early colonial times. Its numbers declined rapidly through the 18th and 19th centuries, largely because it was shot for food, novelties, and specimens, and because old-growth lowland forests, its habitat, were felled for timber. The last unquestioned photographic images of the species were taken in northern Louisiana in 1935. However, sight reports have persisted until modern times, as recently as 1999 near Slidell, Louisiana, and 2005 near Brinkley, Arkansas. Because most sightings of this species pertain in fact to Pileated Woodpecker, observers should take care to document and photograph all suspected Ivory-billeds. Voice Call a nasal kent, given in irregular series and likened to calls of Red-breasted Nuthatch; also gives a territorial double-rap: 2 knocks in very quick succession.
99 species: Worldwide. Four species breed in North America.
Swifts (family Apodidae) are mostly dark, highly aerial birds with slender bodies, long wings, short, stiff tails, and small bills. They have very small legs and feet suited to clinging rather than perching. Swifts forage much like swallows, but their closest relatives are hummingbirds; both groups are placed in the order Apodiformes (from the Greek word apodos, meaning "without feet").
|Like many other swallow species, Barn Swallow adults often feed their young in brief hovering flight, without perching, particularly after the young leave the nest.|
Few birds are as suited as swifts to a life in the open air. They rarely rest during the day--stopping mainly at the nest to feed their young--and spend most of their time high in the air, foraging at rapid speeds for aerial insects and floating spiders. Their ability to flap their wings independently of one another increases their aerial agility, already considerable owing to their long, slim wings, which provide both lift and maneuverability. Swifts inhabit most environments except open desert and tundra. Their paired courtship flights, always accompanied by twittering calls (and sometimes by midair copulation), are familiar signs of spring.
They nest mostly in hidden recesses (chimneys in the case of Chimney Swift, caves and crevices behind waterfalls for Black Swift). Nests of the smallest species are half-cups of twigs cemented together and affixed to a vertical surface with saliva; Black Swift makes a horizontal nest of moss and lichen. All North American swifts migrate southward in autumn, and most winter in the tropics.
Populations of swifts all seem to be in gradual decline. It is almost certain that air pollution, habitat loss, and pesticide applications have taken heavy tolls on these and many other insectivorous birds.
Identification of Swifts:
Birders often find themselves looking up at hose remarkable aerialists, swifts and swallows. During their migration, many species mix together in large flocks, and identification of single birds may rest on quick impressions of shape and plumage pattern.
Most swifts observed in a given region are of the expected species--Chimney Swift in the East, and the rather dissimilarly shaped Vaux's, White-throated, and Black Swifts in the West. The two Chaetura swifts, Chimney and Vaux's, occasionally stray out of range. Vaux's Swift appears more stubby-tailed and -winged in a mixed flock with Chimney Swift and tends not to show Chimney's apparent bulge in the outer remiges (a feature best observed on birds with wings fully extended). Most Vaux's have paler, ashier throats and contrastingly ashy rumps. Swallows Adult swallows are often vividly colored and easy to identify, but many juvenile swallows are mousy brown above and lack the distinctive iridescent colors of adults.
89 species: Worldwide. Eight species breed in North America.
Swallows (family Hirundinidae), unlike swifts, are passerines (perching birds), and they are regularly seen resting on utility wires, fences, and clotheslines, something that swifts cannot do because of their tiny feet. Swallows are more robust of body and wing than swifts, with larger bills and feet (though both are still relatively small); they also have more colorful plumages, often electric blue, green, or purple above and sometimes with rufous accents. Except for the sexually dimorphic Purple Martin, males and females are similar, though females are often noticeably less colorful.
Like swifts, swallows forage by chasing aerial insects on the wing, but their flight appears less erratic. While most forage at lower altitudes than swifts, several swallow species are known to forage very high in the atmosphere. Swallows are often found in open terrain near water; like swifts, they often sip water or even bathe while flying, skimming and splashing low over a lake or river.
They nest in recesses, from old woodpecker cavities and nest boxes, to cavities in riverbanks, to spaces in old wharves and farm buildings. Many species nest in colonies: Cave and Cliff Swallows, which form large colonies, attach vertical mud nests to the walls of old barns and caves and, more recently, to the undersides of bridges and overpasses. Purple Martin readily uses martin houses and hollow gourds set out for them. Most North American swallows are long-distance Neotropical migrants.
Like many other swallow species, Barn Swallow adults often feed their young in brief hovering flight, without perching, particularly after the young leave the nest.
Swallow populations in North America appear to be stable or even, in the case of Cave Swallow, increasing.
Identification of swallows:
Adult swallows are often vividly colored and easy to identify, but many juvenile swallows are mousy brown above and lack the distinctive iridescent colors of adults.
The adult Barn Swallow is easily identified by its deeply forked tail. Juvenile Barn, however, has a much shallower fork and variable rufous on the throat and can be confused with Cave and Cliff Swallows. Barn Swallow has long, narrow wings that come to a neat point; Cave and Cliff have wider, more blunt-tipped or rounded wings and square tails.
|Northern Rough-winged Swallow||Tree Swallow, juvenile||Bank Swallow||Violet-green Swallow, juvenile||Purple Martin, juvenile|
When in flight, the four brown-backed swallows--Bank, Northern Rough-winged, and juvenile Tree and Violet-green Swallows--show quite distinctive shapes. Tree Swallow is the largest of the four and has wide, full wings. Violet-green Swallow, by comparison, looks more slender in both body and wings, and its wings appear proportionately longer. The white sides of the rump are much more extensive on Violet-green Swallow and only narrowly divided down the middle of the rump (in both adult and young birds).
Tree Swallow in juvenal plumage often shows a dusky, indistinct breast band that is sometimes broken in the middle; this can lead to confusion with Bank Swallow--a smaller and daintier species with narrow wings, a rather long tail, and a much more distinct breast band that sometimes has a distinct cusp at the midpoint.
Northern Rough-winged Swallow may seem drab and thus difficult to identify, but in North America it is the only brown-backed swallow in which the breast, throat, and face are washed with brown (buffier in young birds). Its proportions are more like those of Tree Swallow--somewhat broad-winged and short-tailed-- but there is no contrast between the throat and head in any plumage. Beware the much larger juvenile Purple Martin, in which the throat is washed with gray.
320 species: This strictly American family is most numerous in South America, especially in the Andes. Only 14 species breed regularly in North America, of which only the Ruby-throated is widespread in the East.
|Male Ruby-throated Hummingbirds often drive females from flowers and feeders.|
Hummingbirds are extraordinary creatures: they are the smallest of birds, with the smallest of eggs; they are the only birds able to fly backward, and their wings beat faster than any other bird--up to 30 beats per second. All hummingbirds have slender bodies, wings, and bills and very small feet adapted only for perching; however, they are classed not with the passerines (perching birds) but with their distant relatives the swifts in the order Apodiformes.
Male hummingbirds have throat patches (gorgets) of iridescent colors to which ornithologists have given vivid labels--ruby, amethyst, and sapphire. These colors are generated by complex feather structures that reflect certain wavelengths of light but not others. Males use their jewel-like gorgets, and in some species crowns, in courtship displays and territorial clashes; adult females and young males lack full gorgets and are usually more subtly plumaged than adult males.
Hummingbirds forage on flower nectar, using their long, grooved tongues to wick the fluid directly to the throat. Many species are attracted to red flowers that are tubular in structure; manufactured hummingbird feeders that imitate this shape and color attract one or more species almost instantly, whether set out in desert washes or alpine meadows. As a hummingbird sips nectar, it often collects the flower's pollen on its head; cross-pollination occurs as the bird moves from flower to flower. In addition to nectar, hummingbirds eat a great variety of insects and other invertebrates, some spotted from a perch and caught on the wing, others gleaned from foliage, still others picked from the ground or from emerging swarms. Some hummingbirds take tiny insects trapped in sap wells made by sapsuckers.
Male hummingbirds perform dazzling courtship displays: they make steep dives from high in the air, often following up with an aerial dance of side-to-side flying or other acrobatics and much calling and flashing of the gorget. Hummingbird males are promiscuous, mating with as many females as possible within their territory (and even outside it). The males leave the females to construct the nest and raise the young alone. They lay two white eggs in a soft very compact nest made of down.
Many hummingbird species are strongly migratory. Ruby-throated Hummingbird, which breeds as far north as Canada, migrates across the Gulf of Mexico to the Yucatan Peninsula; Rufous Hummingbirds from Alaska may travel as far as the mountains of Mexico. Other species wander widely; at least seven have made their way from the tropics into the United States. In some cases, western species have begun to spend the winter season in the Southeast instead of tropical areas, apparently attracted by feeding stations. Despite their extraordinary popularity, hummingbirds are some of the least understood of North America's birds from the standpoint of conservation. A few range-restricted species, such as Allen's and Buff-bellied Hummingbirds, are apparently declining because of habitat loss. The population sizes and dynamics of most other species are either unstudied or very poorly known.
Identification of Hummingbirds:
More and more hummingbirds are observed far from their typical ranges. There are now records of 16 different species east of the Mississippi, where for generations the only hummingbird likely to be seen was Ruby-throated (with a few Rufous Hummingbirds turning up in fall and winter). This change in the distribution of these birds means that many more people are faced with the complexities of hummingbird identification. The mostly green-backed females and immature birds are far more difficult to identify than adult males, and some, such as female and immature Allen's and Rufous Hummingbirds, cannot be reliably identified in the field.
|Black-chinned Hummingbird (Archilochus)||Ruby-throated Hummingbird (Archilochus)||Anna's Hummingbird (Calypte)||Costa's Hummingbird (Calypte)|
Archilochus and Calypte:
Anna's and Costa's Hummingbirds (Calypte) are easily confused with Black-chinned and Ruby-throated (Archilochus). Both Ruby-throated and Black-chinned are smaller and much less robust than Anna's, with slender bodies and necks, when alert, and smaller heads. They are closer to Costa's in proportion but have longer tails that project just beyond the wingtips at rest (wingtips cover the tail tip in Costa's).
Ruby-throated and Black-chinned females and juveniles are very similar. Black-chinned looks more bronzy above and lacks the emerald green shown in Ruby-throated's back and crown. Ruby-throated shows a sharper contrast between the white throat and the crown and auriculars. The outermost primaries are pointed in female Ruby-throated, more bulbous and curved in Black-chinned. Black-chinned females often have very long bills.
Anna's and Costa's Hummingbirds rarely stray to the East, but westerners often struggle to distinguish silent females and juveniles (Anna's loud call note is distinctive). Costa's is somewhat smaller than Anna's, with a longer, often decurved bill; its shorter tail does not project beyond the wingtips at rest. Costa's has pale, mostly unmarked under parts; Anna's has greenish dusky mottling on the flanks and dusky stippling on the lower throat. Costa's looks pale-faced; Anna's is more dusky and mottled in the face.
|Calliope Hummingbird (Stellula)||Broad-tailed Hummingbird (Selasphorus)|
Stellula and Selasphorus:
Female Calliope and Broad-tailed Hummingbirds (Stellula and Selasphorus, respectively) are both regularly mistaken for Allen's or Rufous Hummingbirds (also Selasphorus), which are often more strongly marked below and show much more extensive rufous in the rectrix bases. Calliope is tiny and short-billed, and its short tail is completely covered by the wings at rest--unlike any of the three Selasphorus. A flying Calliope looks compact, even stubby in flight, with its short tail and bill and "pot-bellied" appearance. Broad-tailed Hummingbird is larger than Rufous and Allen's, and its much fuller, broader tail is apparent with close, comparative study. Like Calliope, female and young male Broad-tailed Hummingbirds often show a neatly speckled throat (a "five o'clock shadow").
Tyrant flycatchers in North America are part of the enormous family Tyrannidae, which contains more than 400 species; 35 species in 10 genera nest in the United States and Canada, from deserts to boreal forests, and another 10 have been seen as vagrants north of Mexico and the Caribbean.
|Olive-sided Flycatcher with a white lined sphinx moth.|
Tyrant flycatchers evolved in the New World tropics, and their diversity there is remarkable. Tyrannidae is the only family of suboscine passerines (a tropical American group that includes cotingas, woodcreepers, and antbirds) that extends northward across the Mexican border. Suboscines, unlike oscines (all other North American passerines), do not learn their songs; rather, their songs are innate.
Flycatchers are upright-perching, small- to medium-sized passerines with typically broad-based bills surrounded by rictal bristles. Their rather long, pointed wings are typical of long-distance migrants (temperate-zone nesters generally migrate to the tropics in winter). Most species are brown, gray, or greenish above and a paler whitish or yellowish below, and many have wing bars. Although some tropical species are strikingly patterned, most flycatchers are subtly plumaged and quite similar to each other.
As their name implies, flycatchers take mostly insect prey, primarily flying insects; fruit forms an important part of the diet in migration and on the wintering grounds for some of the larger species. Larger flycatchers and the pewees, including Olive-sided Flycatcher, usually sit on a conspicuous perch and watch for passing insects, which they fly out and capture with the bill in midair, returning to the same perch. Smaller species tend to show less fidelity to one perch. A few species, especially the phoebes and the larger flycatchers, also take prey from the ground, including spiders, small lizards, and even small birds such as hummingbirds.
Most tyrannids sing to attract mates and mark territory; a few, notably the kingbirds and Vermilion Flycatcher, have striking aerial displays as well. Many species have dawn songs that differ from their daytime vocalizations. Temperate zone flycatchers make cup-shaped nests, placing them in the fork of a tree or along a limb; Yellow-bellied and Cordilleran Flycatchers sometimes nest on or near the ground. Myiarchus species nest in cavities, as does Sulphur-bellied Flycatcher. Several other tropical species, notably becards and kiskadees, make larger spherical nests with side entrances.
Populations of tyrant flycatchers have declined in many areas. The most severe declines appear to be among flycatchers of the genus Contopus, especially Olive-sided Flycatcher and the wood-pewees. Several Empidonax may also be declining, and one, the southwestern subspecies (extimus) of Willow Flycatcher, is federally listed as endangered: its limited riparian habitat supports fewer than 500 pairs. The reasons for declining flycatcher populations probably lie in habitat changes across the Americas, including the fragmentation and destruction of forests and over browsing of the forest floor by deer. Other threats include pesticide use and the proliferation of Brown-headed Cowbirds, which are brood parasites.
Identification of Tyrant Flycatchers:
Certain tyrant flycatchers, such as the gaudily plumaged male Vermilion Flycatcher and the long-tailed Scissor-tailed Flycatcher, are among the most recognizable of North American birds. The more plain colored flycatchers, however, are often frustratingly difficult to identify. Experienced birders pay careful attention to details of bill shape, primary projection, plumage color, and vocalizations.
|Dusky Flycatcher (Empidonax)||Eastern Wood-Pewee (Contopus)||Ash-throated Flycatcher (Myiarchus)||Gray Kingbird (Tyrannus)||Eastern Phoebe (Sayornis)|
Empidonax flycatchers (11 species north of Mexico), known as "empids," are all small birds, 5-6" (13-15cm) in length, that are grayish brown to greenish gray above and paler below and have wing bars and usually eye rings. To identify an empid, take note of its overall plumage colors, primary projection (the distance that the tip of the primaries projects past the tips of the tertials), color and proportions of the bill, shape and tone of the eye ring (if present), and proportions of the body (head and tail). Bills of these species can look remarkably similar; most are short and thin, often with a pale mandible. When observed from below, most eastern empids have broad, spade shaped bills, as do Pacific-slope and Cordilleran Flycatchers; the western-breeding Dusky, Hammond's, and Gray Flycatchers have narrow bills with a dark tip below.
Contopus flycatchers (4 species, plus 1 vagrant) are slightly larger, measuring about 6-8" (15-20cm). Some Contopus, namely the wood-pewees, are easily confused with Empidonax flycatchers. Wood-pewees are best distinguished by their relatively long wings, reaching almost halfway down the tail, and long primary projection; they never flick their wings and tail (unlike most empids), and they lack eye rings, which most empids have. The larger, larger-billed Contopus species (Olive-sided Flycatcher and Greater Pewee) are more distinctive; a distant Olive-sided can be mistaken for a kingbird.
Myiarchus flycatchers (4 species, plus 2 vagrants) are larger species, 7-9" (18-23cm) long. All have rufous-edged primaries (and usually rectrices), a yellowish belly, gray tones in the throat and upper breast, and a brown back. Most have bills that are noticeably heavier than those of the small flycatchers, although Dusky-capped Flycatcher has a bill comparable in length to the larger Contopus. Identification often requires listening to vocalizations and studying the bird's proportions, pattern of rufous in wings and tail, and other plumage patterns.
Tyrannus flycatchers (9 species, plus 1 vagrant), the kingbirds, are rather heavy-billed, stocky birds that range in size from 81/2" (22cm) in Eastern Kingbird to 16" (41cm) in Fork-tailed Flycatcher, including its long tail. Most kingbirds can be correctly identified with careful study. The very similar Tropical and Couch's Kingbirds are best distinguished by vocalizations.
Sayornis flycatchers, the phoebes (3 species), measure about 7" (18cm). These open-country birds have long tails and very plain plumages, lacking eye rings and wing bars. All habitually "dip" or flare the tail, which makes them easy to identify; Gray Flycatcher, an empid, also dips the tail.
74 species: Mainly Old World. Only two species live in North America, both of them migratory.
|Northern Shrike with impaled prey item.|
Shrikes (family Laniidae) are medium-sized passerines of open-country habitats. These birds recall a small jay in overall shape and in fact are possibly related to corvids. Both North American shrike species are plumaged in gray, black, and white; younger birds show browner tones above and faint barring below. Northern Shrike, the larger species, nests in boreal forests and muskeg and is seen regularly only south to the northernmost United States in winter; Loggerhead Shrike nests mostly south of Canada and ranges southward into the deserts of Mexico. Brown Shrike of Eurasia has been recorded eight times as a vagrant to North America, mostly in Alaska.
Both Loggerhead and Northern Shrikes are regularly confused with Northern Mockingbird, which has much more white in the wings and tail, a more slender bill, and a different flight style that lacks the rapid wing beats and often undulating path of the shrikes. The black mask of shrikes (absent in mockingbirds) probably functions, like a falcon's mask, to absorb glare in the well-lit habitats shrikes occupy.
Shrikes are unique among passerines in that they feed like birds of prey, taking birds, rodents, and large insects in swift, direct capture much as kestrels do. Their short but powerful bills have a hooked maxilla with a small tomial notch (a tiny toothlike serration), as in a falcon's bill, which they use to dispatch prey quickly, often with a bite to the neck. While shrikes lack the talons of a raptor, having simple perching feet like other passerines, they can tear into prey using their heavy bills. Like owls, shrikes regurgitate pellets of indigestible material. Shrikes cache what they catch, using barbed wire or thorn trees to display prey items; this larder presumably functions both to impress potential mates and to indicate occupied territories. Because they rely on sites where they can impale prey and find hunting perches, shrikes shun grasslands that lack trees, unless manmade features such as utility poles are available. Northern Shrike with impaled prey item.
Courtship among shrikes is not often observed. Both sexes bow and flash the white in their wings and tail, and the male sings a rather sweet, simple song or calls quickly. Territorial disputes look similar, with much posturing and rapid chattering. Shrike nests are simple cups of twigs and grasses set in small crotches in trees. The nests of Loggerhead Shrike are easy to find, often placed in isolated trees near prime feeding areas.
Shrikes are rarely observed in true migration, as most make only facultative movements when prey becomes scarce. Cyclic population crashes of voles in Canada bring hundreds of Northern Shrikes southward into the United States; these flights occur every five years or so with varying intensity.
The few Loggerhead Shrikes that now nest in the Northeast (sometimes designated as subspecies migrans) were once uncommon migrants and wintering birds along the East Coast, but this population is all but extirpated. Another subspecies, mearnsi, which nests only on San Clemente Island off southern California, is likewise imperiled: just 76 birds remained in the wild as of 2004.
51 species: New World, mostly tropical and subtropical. Twelve species breed in North America, all in the genus Vireo.
|Vireos, such as this Warbling Vireo, are sometimes mistaken for warblers of kinglets, which forage by gleaning like vireos but have thinner bills and legs.|
Vireos are small land birds that resemble warblers but have heavier bills and heads. Once assumed to be close relatives of warblers, vireos are now thought to be most closely related to shrikes (the tomial notch near the tip of the maxilla perhaps hints at this relationship) and also to corvids. Vireos have heavier legs than warblers, often with a bluish tone; this can be helpful for identification. In plumage, vireos (genus Vireo, a Latin word whose root means "green") are plainer than warblers overall: mostly olive or gray above and paler below, with touches of yellowish in some species. Most have distinctive markings around the eyes, either "spectacles" or a supercilium, and most have wing bars in fresh plumage.
Like most warblers, vireos forage by gleaning prey from vegetation, from low scrub up through the canopy; they eat insects and their larvae and also, especially during the non-breeding season, small fruits. While foraging, vireos often seem less animated and more methodical than warblers, scanning from a perch before moving to the next branch; however, smaller vireos, such as Black-capped and White-eyed, seem to be in constant, nervous motion when foraging. Hutton's Vireo closely resembles Ruby-crowned Kinglet and often flicks its wings like a kinglet, while Bell's and Gray Vireos use distinctive tail movements while foraging. These actions of wings and tail probably serve to startle prey. Some vireos make short sallies from a perch to pick insects, much as a flycatcher does.
|Adult Red-eyed Vireo, showing tomial notch in maxilla.|
Male vireos sing to advertise territories and occasionally engage in song flights; unlike most passerines, males of some species sing from the nest. Vireo songs are often quite similar, as between Plumbeous and Yellow-throated or Philadelphia and Red-eyed. Philadelphia may actually imitate a Red-eyed's song to keep that species away from its territory. The calls of most vireos (not described in the species accounts) are quite similar and in some cases indistinguishable among species--a descending, raspy, nasal set of scolding calls with a catlike quality. Both sexes guard their territory against intruders. Most vireos make cup-shaped nests that hang on the fork of a small branch; only Gray Vireo regularly nests on top of a branch. All species except Hutton's Vireo migrate southward in winter.
Populations of most vireos are relatively stable across the continent. Black-capped Vireo and the pusillus subspecies of Bell's Vireo (called Least Bell's Vireo) are both federally listed as endangered, their numbers reduced by habitat loss and brood parasitism by Brown-headed Cowbird.
51 species: North America, Eurasia, and Africa. Eleven species breed in North America.
|Carolina Chickadees, like other parids, build nests in cavities, and both parents feed the young.|
Chickadees and titmice (family Paridae) are small, agile, animated passerines of diverse woodlands--from dwarf willow fens of northern Alaska, to juniper-clad foothills of the Great Basin, to the suburban East. Eleven species breed in North America, and one Eurasian species, Great Tit, has trayed to Alaska. In structure, chickadees and titmice share some attributes: relatively compact bodies, very short, conical bills, and fairly long tails. Chickadees usually have a pale cheek set off by a dark cap and bib. Titmice, larger on average, are gray overall with crests and few other adornments; the exception is Bridled Titmouse, which has a more intricate head pattern. Parids eat a variety of insect matter, seeds, and berries. They cache food, much like a corvid does, for later consumption; this behavior can sometimes be observed at bird-feeding stations, although usually the birds retrieve a seed from the feeder and fly a short distance away to open and eat it. With much coaxing, some species learn to take seeds from the hand.
Parids and their allies do not have elaborate courtship displays. Males sing and feed females, and both sexes investigate potential nest cavities, where they make cup-shaped nests. Many species readily accept nest boxes. Like the other families treated in this section, they have a monogamous breeding system; some apparently mate for life.
Away from feeders, non-breeding parids forage in family groups or in company with nuthatches, kinglets, small woodpeckers, Brown Creeper, vireos, and warblers. In these groups parids lead the flocks, often announcing the presence of a predator, such as an owl, snake, or hawk, with noisy scolding. Although harassing a predator at close range would seem to be a risky affair, "mobbing" serves to draw the attention of numerous small birds to the location of the predator and probably teaches young birds to recognize potentially dangerous animals. Imitating titmice calls (called "pishing") can be effective in drawing out woodland birds, apparently because titmice are the sentinel species in these mixed-species flocks or "guilds" of woodland birds.
25 species: North America and Eurasia. Four species breed in North America.
|Nuthatches are often spotted moving up and down on the trunks and limbs of trees. They eat both seeds, for which they have earned the name "nuthatch," and insects.|
Nuthatches frequent much the same woodland habitats as parids, but their structure is quite different. They are stocky birds with long, pointed bills, short tails, and very strong, sizable feet with which they cling to tree bark. Both nuthatches and woodpeckers are "scansorial" birds, adapted to climbing; but unlike woodpeckers, which mostly move upward around a tree, nuthatches move all around the trunk and limbs.
Like parids, nuthatches nest in cavities and are not predictably migratory. Red-breasted Nuthatch does stage large-scale fall irruptions from montane and boreal habitats in years when food is scarce. Brown Creeper (family Certhiidae), resident in many sorts of mature forests, is reminiscent of a tiny woodpecker. Creepers forage up trees with quick, hitching motions made possible by their stiff tails and strong legs. Their thin, decurved bills are weaker than the bills of woodpeckers and better suited for prying tiny prey from bark crevices. Creepers make nests behind loose strips of bark and, like nuthatches, sometimes roost communally in a cavity during cold weather.
North America, Eurasia, and Africa. One species breeds in North America.
Verdins are very small birds with short wings, relatively long tails, and sharply pointed bills. A few species undertake shot migrations, but most are nonmigratory. All make elaborate nests. Verdin most resembles parids, especially chickadees, in structure, with its fine, conical, pointed bill and rotund body and head. Instead of a chickadee-like bib and cap, however, the adult Verdin has a yellow head and thus can be confused with warblers. This species forages by gleaning and, like parids, readily hangs upside down to reach the tips of light branches. It makes a spherical twig nest with a side entrance and apparently builds separate roosting nests as well.
8 species: North America, Eurasia, and the East Indies. Only one species in found in North America.
These are tiny, active, mainly insectivorous birds with small, somewhat conical bills, short rounded wings, and long tails. Bushtits are social birds, most often seen traveling in large groups comprised of several families that hold large communal territories, but they also regularly travel with foraging flocks of other passerines, including parids and warblers. They noted for their pendant, bag-shaped nests, often attached to mistletoe.
264 species: Old World, plus one in Western North America.
The Wrentit is an inconspicuous, sparrow-sized bird confined to the chaparral habitat where it nests and finds its insect food.
Verdin, Bushtit, and Wrentit (families Remizidae, Aegithalidae, and Timaliidae, respectively) are birds strictly of the American West and Mexico and are never observed far from their respective habitats. Bushtit also resembles parids but has a longer tail and an even smaller bill. Wrentit is even longer-tailed than Bushtit and has a larger, slightly decurved bill. This species is sedentary; nesting adults form long-term monogamous pair bonds and are believed to remain within their territories for life, as long as the habitat remains suitable.
A diverse group of families called "allies"of the chickadees and titmice family (Paridae) are treated in this section of the guide, even though some of these are not currently considered close relatives of parids. Until recently, for instance, Bushtit and Verdin were considered parids, but the latest research suggests that these birds are the sole New World representatives of two Old World families, the long-tailed tits (Aegithalidae) and the penduline tits (Remizidae), respectively. The unusual Wrentit, restricted to California and Oregon, recalls both Bushtit and wrens but appears to be a member of the babbler family (Timaliidae)--also an Old World family with no other representatives in the New World. Brown Creeper, the only North American representative of its family (Certhiidae), and the four species of nuthatch (Sittidae) often join parids in foraging parties during the non-breeding season, along with many other woodland species. The evolutionary relationships between creepers, nuthatches, and parids are not well understood, and their placement together is based more on their shared habitat and association in the non-breeding season than on similarities in plumage and structure.
Conservation Status, Chickadees, Titmice and Allies:
Of the species in these six families, conservationists have most concern for those with the most restricted ranges, the smallest populations, and the most threatened habitats. High on the list is Wrentit, whose chaparral habitat has been very heavily developed; though this species tolerates some degree of fragmentation, it does not thrive amid intensive development. Range-restricted species, such as Bridled and Oak Titmice, should be monitored over the long term for declines. Brown-headed Nuthatch is a victim of habitat loss in southeastern pinewoods, and Verdin populations in thorn scrub of the Sonoran Desert have declined sharply as that habitat is modified or eliminated. Mountain Chickadee appears to have undergone a recent decline for reasons that are not clear.
For help in identifying chickadees, titmice, bushtit, wrens, and wrentit, see "Identifying Small Woodland Birds," below.
75 species: The Western Hemisphere; one wide ranging species, the Winter Wren, also occurs in Eurasia. Nine species breed in North America.
|Male Cactus Wrens sing many subtle variations of a simple song; females deliver a quiet, higher-pitched song.|
Wrens (family Troglodytidae) are small, mostly brown passerines with thin, decurved bills and often long tails that they hold cocked above the back. They occupy a wide array of habitats, from border deserts to the rocky Aleutian Islands, and spend most of their time near the ground. To many suburban dwellers, wrens are familiar visitors to backyard brambles, brush heaps, and feeding stations; several species readily accept nest boxes and will nest even in old boots, automobiles, or outhouses. Wrens are probably relatives of the gnatcatchers (and the tropical gnatwrens), which are most closely related to Old World warblers, but their relationships and phylogenetic placement have yet to be clearly determined.
Although this group's family name derives from the Latin for "cave-dweller," most of the nine species that breed in North America never enter caves. But wrens are expert foragers in tight spaces, including thickets, tangles, tree falls, and rocky crevices--any site that supports an abundance of insects, millipedes, spiders, and their eggs, which are a wren's chief foods. Some species also eat seeds and small fruits, especially in the cooler months, and a few eat snails, small frogs, lizards, or other small vertebrates. Their long, thin bills give them almost a surgeon's precision in plucking prey from crannies.
Wrens sing to attract mates and defend territories and are among the most musical of American birds. Their repertoires are variable among species: Cactus Wren seems to sing the same chugging song year after year, whereas Marsh Wren may sing more than 150 song types over the breeding season. Females sometimes counter-sing or duet with the males, especially in Carolina Wren, though their vocalizations are less varied and musical. Wrens build cup-shaped or spherical nests mostly in bushes or reeds, but some nest in crevices or cacti. Most of the wrens that nest in northern North America migrate southward in autumn or at least withdraw from northern parts of their range.
Wren populations in North America are thought to be stable, with a few exceptions: in the Southwest, Cactus and Rock Wrens may have lost ground to suburban development, and in the East, Bewick's Wren has declined sharply.
|American Dippers often submerge their heads to look for food before plunging into the water.|
5 species: In temperate zones of the Old World and the Americas. Once species breeds in North America, where it is largely nonmigratory.
American Dipper (Cinclidae) is a gray, heavyset bird, about the size of a thrush. Dippers have short tails and pointed bills; their powerful legs and feet are adapted for doing something no other passerine does: swimming and walking underwater, where they forage for invertebrates. Dippers make round nests of mosses and various plants, placing them near streams, usually on a ledge, cliff, or underside of a bridge.
Kinglets, Warblers, Gnatcatcher, and Allies
Families: Parulidae, Sylviidae, Regulidae, and Peucedramidae
|Adult male Canada Warbler with insect|
New World warblers (family Parulidae), Old World warblers (Sylviidae), kinglets (Regulidae), and Olive Warbler (Peucedramidae) are all small passerines with thin, pointed bills, active foraging habits, and usually colorful plumages, particularly in breeding adult males. The New World warblers are sometimes called "wood-warblers" to distinguish them from the Old World warblers, a family represented in North America by the gnatcatchers (genus Polioptila) and by Arctic Warbler. Until very recently, Olive Warbler was thought to be a parulid, but studies suggest a possible close relationship to finches (fringillids). Despite the many similarities in these groups, there are important differences. For example, like other oscine passerines of the Americas, parulids and Olive Warbler have nine primaries, while sylviids have ten; this means that American parulids appear to be more closely related to blackbirds and cardinals than to Old World warblers.
Warblers and their allies are tenacious, adaptable, hardy birds that have radiated into habitats as diverse as their jewel-like colors: from marshes and muskeg to thorn scrub and mangrove forests. Most species fare poorly, however, in developed urban and modern agricultural environments, which have too little in the way of insect life, nest sites, or both. Some warblers specialize to a greater degree than others in their choice of habitat: Kirtland's Warbler, for instance, nests almost entirely in very young jack pine forests found in Michigan, and Golden-winged Warbler selects recently disturbed and early successional habitats (which are ephemeral and increasingly scarce in most parts of its range). Bachman's Warbler, probably extinct, was a species of southeastern swampwoods, apparently around stands of native cane; these habitats disappeared as flood regimes of many rivers were altered, although it is not known if this was a cause of the species' disappearance.
|Blue-gray Gnatcatcher is the only gnatcatcher species that migrates. Like many other American passerines, it is currently expanding its range northward.|
On migration, warblers, kinglets, and gnatcatchers will forage in habitats similar to their nesting areas when possible, but they readily take advantage of local abundances of insects or, in the case of the larger species, small fruits. Each species has a consistent manner of foraging. Yellow-rumped Warbler is perhaps the most flexible in its feeding techniques: it takes food by flycatching, gleaning, hover-gleaning, creeping (like a nuthatch), ground-sallying, and plucking. Most warblers and allies forage by just one or two of these methods, and some have quite specialized manners of hunting for insects and their larvae. Swainson's Warbler, for instance, walks through leaf litter and makes vibrations with its large feet, presumably to startle prey; Worm-eating Warbler seeks out insects in curled clusters of dead leaves; Black-and-white Warbler forages on trees, like nuthatches; and American Redstart flashes and fans its tail as it forages, flycatching the insects it flushes. Warblers seldom take vertebrate prey, although waterthrushes and other large species sometimes capture minnow-sized fish or small salamanders. Kinglets, with their tiny bills, are adept at removing tiny aphids and other arthropods and their eggs from tight cracks in bark and coniferous needle clusters; because these resources are available through the winter, many kinglets remain in the United States during the non-breeding months.
For such large and diverse groups of birds as the sylviids, regulids, and parulids, it is surprising that mating systems are so uniform. Virtually all species are seasonally monogamous (although, as in many other passerine groups under study, there is increasing evidence of extra-pair copulations). Males arrive ahead of females on the breeding grounds and sing almost constantly, even as they forage. Courtship involves mostly singing, posturing, and in some species song flights. Males sing even after the young have fledged in some cases, but song activity drops sharply after the eggs hatch. In a few species, females are also known to sing, albeit usually quietly and infrequently. Many American warblers have a complex, rambling dawn or dusk song that is distinctly different from the day song(s) and appears to be intended for territorial maintenance. Parulids, sylviids, and regulids all build cup-shaped nests, including the cavity-nesting Lucy's and Prothonotary Warblers; some species place their nests on the ground, others quite high in trees or bushes. Soon after the young fledge, most warblers begin their long migrations to the New World tropics.
Populations of many warbler species have declined across large parts of North America as a result of clearcutting, development, and fragmentation of many types of forest. The same activities, however, have often produced local increases in species that utilize disturbed and regenerating habitats, such as Prairie Warbler and Common Yellowthroat. Bird conservationists are currently most concerned about localized species with very small populations (Kirtland's, Golden-cheeked, Lucy's, Hermit, and Colima Warblers) and about widespread species whose declines are well documented and appear to be steady (Cerulean, Golden-winged, and Prothonotary Warblers).
Distinguishing between the many different small birds that inhabit a local park can be daunting. While woodpeckers, hummingbirds, and owls give themselves away quickly by their distinctive shapes and behaviors, the passerines--perching birds in the order Passeriformes, of which at least 402 species have been recorded in North America--have a remarkable number of look-alike species and families. Below is a thumbnail comparison of many types of small birds that might frequent a local birding spot with wooded areas or chaparral. (See also "Small Brown Landbirds," which covers mostly ground birds.) When looking at an unfamiliar small bird, pay attention to its behavior, overall structure, calls, and bill shape.
|Yellos-bellied Flycatcher||Blue-gray Gnatcatcher||Boreal Chickadee||Oak titmouse||Bushtit|
Flycatchers can be difficult to identify, especially the smallest species of the genus Empidonax. Like many woodland and scrubland birds, most flycatchers have eye rings, wing bars, and fairly plain plumages overall. Unlike other small woodland birds, flycatchers usually perch upright, watching for and then chasing passing insects, which they capture with an often audible snap of the bill. Many species twitch the wings and tail when perched.
Vireos are compact, mostly plain passerines with stout, slightly hooked bills and rather heavy legs. Vireos tend to move slowly and deliberately through trees and brush, looking for insects and their larvae and for fruit. The smallest species, however, forage quite actively, more like a kinglet or warbler, and have shorter and less bulbous bills than the larger species. The small Hutton's Vireo is very easily mistaken for a Ruby-crowned Kinglet, although it does not forage as actively as a kinglet.
Kinglets are truly tiny birds with the smallest of bills. They forage almost continuously, Ruby-crowned often flicking its patterned wings as it moves through the trees, and can hover at the tips of branches to glean tiny insect larvae. Though superficially similar to warblers, vireos, and flycatchers, kinglets have even thinner bills, thinner legs, and shorter tails.
Warblers most resemble vireos, but nearly all warblers have thinner legs and thinner, pointed bills that lack the vireo's slight hook at the end. Warblers are rather active foragers and have many strategies for taking insects and larvae, including flycatching; most glean insects directly from branches, as vireos do. Warblers are most confusing when in their plainest plumages, whether streaky juvenal plumage (held only briefly) or first-fall plumage. Breeding females and non-breeding adults can also be confusing, but in most species they have at least a hint of the head or wing pattern of the breeding male. Even the drabbest of warblers often have distinctive tail spots or a rump patch--plumage characteristics not shared with vireos, kinglets, or flycatchers in North America.
Gnatcatchers, with their long tails and active foraging habits, remind many observers of tiny mockingbirds. These very slender, tiny-billed birds chase insects in the air like flycatchers but move through the vegetation more rapidly, more like a kinglet, constantly flipping the tail to flush prey. Although distinctive, gnatcatchers can be confused with the even shorter-billed Bushtit, which travels in flocks most of the year. Pale females of the western gnatcatchers might also be taken for flycatchers but for their different foraging behaviors and very thin bills.
Chickadees are among the most familiar of woodland and backyard birds. They spend most of their time foraging actively in trees for tiny insects and larvae, often hanging upside down. In most cases, the dark cap and bib make them instantly recognizable, but some worn birds, especially of the brown-capped species, can have indistinct head patterns. Like their relatives the titmice, chickadees have short, stout bills and relatively heavy legs, but chickadees are smaller and slimmer than titmice. Titmice and chickadees often form mixed-species foraging flocks in the non-breeding season, announcing their presence with their similar calls.
Titmice are mostly plainer and larger than chickadees, and some are plainer than small flycatchers; titmice lack wing bars and eye rings, which many flycatchers have. Titmice are usually quickly recognized by their calls, active foraging behavior, short crests, and short, stout, pointed bills.
Bushtit is not much more colorful than a titmouse but is likewise distinctive. Like a kinglet, Bushtit is a tiny bird with a very small bill, but it has a long tail for its size and often looks fluffed up. It is among the most active of birds, moving through brush quickly to glean insects and larvae. After the breeding season, Bushtits gather in large flocks; flockmates often follow one another single file as they cross an opening.
Wrens are small, brown birds of woodlands and many other habitats. They spend a good deal of time low in the vegetation or on the ground, using their long, thin, decurved bills to pluck spiders and other prey from crevices. Their tails can be short or long and are often held cocked as they forage. Although wrens do not form flocks, family groups sometimes remain together after the young fledge.
Wrentit looks like a combination of a wren, a Bushtit, and perhaps a titmouse. Usually quite unobtrusive, Wrentit is found mainly in California chaparral. It forages low in the vegetation, using its tiny, slightly decurved bill to take small insects and berries. Though it does not flock with other species, it may eat at bird feeders.
310 species: Worldwide except Australia. Thirteen species breed in North America.
|Wood Thrush populations have declined tremendously in recent decades, a result of fragmented forests and acid rain.|
Thrushes (family Turdidae) are medium-sized, usually plump-looking passerines found around the world in a great diversity of habitats, from bleak, stony tundra to Pacific coastal rain forests to inner city ball fields. Thrushes have sturdy, slim bills, rather long wings, and strong, moderately long legs that are well suited for their mostly terrestrial foraging habits. The larger American thrushes are usually found in woodlands, whereas the bluebirds and Townsend's Solitaire prefer open country with scattered trees.
Most thrushes hop on the ground looking for insects and other arthropods, which they capture with a quick pounce. The open-country species also flycatch or make quick sallies from a perch to the ground. Virtually all thrushes take fruit at some point during the year, usually in autumn and winter. In the non-breeding season, some species, such as American Robin, form large, roving flocks that quickly strip trees of berries before moving on. Males arrive on the breeding grounds earlier than females and sing to mark and defend their territories. Thrushes are famous for their sublime songs, Hermit Thrush and Varied Thrush in particular. After nesting, spotted thrushes migrate to the American tropics, and Northern Wheatear and Bluethroat migrate to African and Eurasian wintering grounds. Most other species withdraw from northern parts of their range.
34 species: New World. Ten species breed in North America. Included in this family are such well-known birds as the Gray Catbird, the Northern Mockingbird, and several thrashers.
Mockingbirds, catbirds, and thrashers (Mimidae) are reminiscent of thrushes in overall build, but they have longer tails, shorter and less pointed wings, and bills that are either longer and decurved (most thrashers) or shorter and thinner. Like thrushes, mimids are fine songsters; in some cases, they imitate other birds' songs (hence the family name, which means "mimics"). Most mimids are terrestrial foragers that lurk in thickets, kicking back leaf litter in search of insects and the like; all species eat fruit as well.
Most mimids appear to be in a pattern of long-term decline, and several thrushes, especially Wood and Bicknell's Thrushes and Veery, also show diminished numbers. These declines are probably related to the fragmentation of habitat, which permits cowbirds and predators better access to nests, to deforestation in the tropics, and to acid rain, which may reduce the abundance of arthropods, snails, and other prey items.
4 species: Central America, one species reaches he southwestern United States.
Silky flycatchers are slender, crested, short-winged, towhee-sized birds. They feed by catching flies or gleaning insects. They also take berries.
Silky-flycatchers (Ptilogonatidae), waxwings (Bombycillidae), starlings and mynas (Sturnidae), and bulbuls (Pycnonotidae) have few North American representatives. All of these birds are comparable in size and shape to mimids and thrushes. Phainopepla is a silkyflycatcher found in the arid Southwest, usually near mistletoe or other small fruit; it makes seasonal movements but is apparently only a short-distance migrant. The two American waxwing species, Bohemian and Cedar Waxwings, are probably close relatives of Phainopepla and likewise wander in search of both insects and fruiting trees.
3 species: Temperate portions of the Northern Hemisphere. Two species breed in North America.
These handsome, sleek, crested birds are named for the unique red, wax-like tips on the wing feathers of the adults. Waxwings are among the tamest of birds, often permitting a very close approach. They are very gregarious and often form large flocks, except in the nesting season, which is usually in late summer. They feed on insects, berries, and fruits.
114 species. Tropical and temperate regions of the Old World. Two species have been introduced into North America.
Members of this family are medium-sized songbirds with large feet and strong bills, often with brilliantly glossy black plumage. They are mainly birds of open country, although a few are adapted for living in forests. Most species are gregarious and some form huge flocks outside the breeding season.
European Starling and Red-whiskered Bulbul are both introduced species in North America; the former is one of the continent's most numerous bird species, while the latter is restricted largely to a small area in Florida.
137 species: Old World tropics. One species has been introduced into Florida.
Bulbuls are generally rather dull-colored birds that travel in flocks and eat fruit or insects. Some are noisy and conspicuous, while others are very retiring and difficult to detect.
117 species: Worldwide. Sixteen species breed in North America, and an additional species is a regular visitor from Mexico.
|Corvids frequently harass or "mob" birds of prey. Here a Fish Crow may be attempting to steal scraps of fish from an Osprey.|
Ravens, crows, jays, magpies, and nutcrackers (family Corvidae) are a diverse group of medium-sized to large passerines with sturdy legs and bills, rounded wings, and often long tails. Their plumages can be simple shades of blue or black or quite stunning, as with the strikingly patterned magpies or the multicolored Green Jay. Corvids are found in every major habitat on the continent; Common Raven, the world's largest passerine, remains year round even in northern Nunavut, enduring the brutal, dark winters.
Much of a corvid's success in difficult environments can be credited to its ingenuity in finding food and its ability to adapt to human-modified landscapes. Its gregariousness appears to be another advantage; birds of this group are quick to share new foraging techniques, whether raiding campsites and picnic baskets, dropping nuts on asphalt roads, or following toddlers for dropped food. Corvids are also among the few birds that appear to use tools, and experiments have shown that they are able to count, to remember the location of thousands of sites of cached nuts, and to find solutions to obstacles in procuring food. Most are omnivores, taking carrion, small animals, nestling birds and eggs, fruit, aquatic vertebrates and invertebrates, worms, waste grain, and other foods. Smaller corvids, especially jays, eat mostly seeds and nuts and also insects and other arthropods. Pinyon Jay feeds on pine nuts; flocks of this species and of Clark's Nutcracker travel widely in search of good cone crops.
|Blue Jay nestlings, like the young of other jays, begin acquiring their feathers at age 2 weeks.|
Corvids are not known for their singing ability; their courtship is limited to quiet singing, animated posturing, and, in ravens, acrobatic paired flights. Jays and crows nest mostly in trees (ravens often nest on cliffs), making cup-shaped nests of twigs and sticks; magpies cover the nest with a dome of sticks. Corvids have rather complex breeding systems. For example, several pairs of Mexican Jays may hold a common territory and feed young in several nests regardless of their parentage. Florida Scrub-Jays assist their parents at the nest for at least a year, and in some areas crows also have nest helpers.
Other than Blue Jay, American corvids are not typically migratory, but many species make irregular movements out of the mountains or northern parts of range, especially when food supplies fail.
Among American corvids, Island Scrub-Jay and Florida Scrub-Jay are federally listed as threatened. Both species have very small populations and ranges and are thus potentially susceptible to diseases such as West Nile virus. Destruction of the fragile Florida scrub habitat has been the chief cause of Florida Scrub-Jay's decline.
95 species, exclusively American.
Blackbirds and their kin (family Icteridae) are medium-sized passerines with straight, pointed bills (shorter and more conical on cowbirds and Bobolink) and relatively long, thick legs that are equally well adapted for perching and walking on the ground. Some species, such as Yellowheaded Blackbird, have large feet that help them balance on aquatic vegetation or mud. The plumages of icterids are often striking and colorful, ranging from brilliant orange and yellow in the long-tailed orioles and the short-tailed Meadowlarks to glossy purple, green, and bronze in the grackles, cowbirds, and blackbirds. Bobolink males are mostly black during the breeding season, with a vivid buttercup nape and white in the wing coverts. In most species, females are less gaudily colored or less iridescent and often have brown rather than black tones.
|Blackbirds, such as these black-winged, congregate in large flocks in the nonbreeding season.|
Many species of icterid, especially the blackbirds, have adapted well to human-modified landscapes. Collectively, their breeding habitats extend from the tundra of eastern Alaska, where Red-winged Blackbirds sing from marshy swales, to the strip malls of southernmost Texas, where gangs of Great-tailed Grackles patrol parking lots for french fries. Blackbirds and grackles forage mostly on the ground for seeds, waste grain, mast, and invertebrates, but they eat a wide variety of other foods--fruits, blossoms, buds, and even other birds, birds' eggs, and nestlings. Orioles are much more arboreal in their foraging, and their diets, while also rich in insects and plant matter, feature more nectar. The longer-billed ground-foraging species, especially meadowlarks, frequently forage by inserting the bill into the ground or dense grasses and opening it to make a gap from which to take prey. Rusty Blackbird and Common Grackle employ this strategy in swamps, where they also sometimes wade into shallow water for aquatic invertebrates.
Breeding systems in blackbirds vary tremendously among the species. The larger grackles have polygynous systems that involve harems: large, dominant males defend a territory and mate with multiple females, a strategy seen frequently in mammals but very rarely in birds.
Red-winged and Tricolored Blackbirds are also polygynous in their mating but do not defend harems; Red-winged males defend distinct territories, whereas Tricolored males do not. Orioles are mostly monogamous.
Cowbirds are brood parasites, laying their eggs in the nests of other songbirds and allowing the host species to feed the young birds. The newly hatched cowbird instinctively jettisons other eggs from the nest, leaving the host birds with just one cowbird fledgling.
Populations of blackbirds have been relatively stable and have even increased in some areas; the stark exception is Rusty Blackbird, whose populations may have decreased by as much as 90 percent in the latter part of the 20th century. Most oriole populations, on the other hand, have shown gradual declines in recent decades, probably because of habitat losses in both their breeding and wintering ranges. Bobolink has also suffered population declines, most likely a result of changes in agricultural practices.
39 species: Chiefly Tropical America. 10 species occur in North America.
Cardinals and their relatives (family Cardinalidae) in North America include Northern Cardinal and Pyrrhuloxia (Cardinalis), the Passerina buntings, the Pheucticus grosbeaks, and Dickcissel (Spiza). A vagrant from Mexico, Crimson collared Grosbeak, has also been recorded in Texas on a few dozen occasions. All cardinalids are small to medium-sized passerines. Breeding adult males often have dazzlingly colorful plumages, while females and young birds are cryptic and plain. Northern Cardinal and Pyrrhuloxia are long-tailed, crested, slender birds with heavy, short bills. The smaller Passerina buntings have more sparrow-like bills and shorter tails. The large Blue Grosbeak, while now considered a Passerina, has a much heavier bill, closer to those of the larger, heavyset Pheucticus grosbeaks. Dickcissel differs from the more typical cardinalids in its plumage and breeding system; it is treated with the Old World sparrows and Bananaquit.
Most cardinalids inhabit weedy fields, thickets, and edge habitats for at least some time during the year; they eat seeds, insects, fruit, flowers, and buds, and most are readily attracted to feeding stations stocked with seeds. The Pheucticus grosbeaks nest in mature forests but can often be found in brambles during migration. Courtship among cardinalids consists of energetic singing, feeding, and some posturing on the part of males. Unusual among songbirds, female Blackheaded Grosbeaks and female Cardinalis sing fully developed songs during the breeding season. Despite the monogamous mating system of birds in this group, extrapair copulation is not uncommon. Where ranges meet, hybridization, especially between Indigo and Lazuli Buntings and Rose-breasted and Black-headed Grosbeaks, is very common.
Most cardinalids are long-distance migrants to the tropics. Dickcissel, which has a polygynous mating system, migrates to the llanos (plains) of northern South America, where it forms enormous flocks in rice fields.
|Buntings, such as this male Indigo Bunting, appear to have simple songs, but there are countless subtle variations in note phrasing, pairing, and pitch among individuals.|
North American tanagers are probably best considered cardinalids, although they are currently placed in the family Thraupidae. They are robin-sized birds with moderately long tails and wings. Tanagers' bills seem intermediate between those of icterids and cardinalids: fairly heavy but also lengthy and somewhat pointed. The vivid red, yellow, and black plumages of breeding adult males rival those of the cardinalids; females are less striking in shades of olive and yellow.
As a rule, tanagers eat much less plant matter than cardinalids, taking mostly insects and their larvae; but they do consume berries and other small fruits in season. Summer and Hepatic Tanagers are avid bee-eaters, capturing bees on the wing and beating them on a branch to remove the stinger. Like cardinalids, Piranga tanagers form seasonally monogamous pairs and defend territories, and females in some species sing.
Cardinalids and tanagers are still relatively common; there have been declines in a few species of tanager, particularly Scarlet Tanager, and in Painted Bunting, the result of habitat loss and brood parasitism by cowbirds.
Identification of Female Tanagers:
Adult male Scarlet and Western Tanagers, two of the more distinctive and attractive passerines in North America, are easy to identify. Male Hepatic and Summer Tanagers are sometimes confused. Female tanagers, however, are much more difficult to identify than males.
|Summer Tanager female||Hepatic Tanager female||Scarlet Tanager dull female||Western Tanager female||Flame-colored Tanager female|
Hepatic and Summer Tanagers Female Hepatic, Summer, and Scarlet Tanagers usually lack wing bars (although Scarlets with weak wing bars have been reported); their plumages are generally a faded yellowish below and darker above. In the Southwest, Hepatic Tanagers can occasionally be seen in the same groves as Summer Tanagers of the cooperi subspecies, especially on migration. Female cooperi birds have bills that are similar in size to the large bill of Hepatic Tanager; but the maxilla of Hepatic is typically darker and heavier, with more curve in the culmen, than that of cooperi. Female Hepatics also have dusky lores and gray-brown auriculars that divide the yellowish crown from the yellow throat and usually extend to the lores, a feature not seen in Summer Tanagers.
Summer and Scarlet Tanagers Female Summer Tanagers in the East are smaller-billed than those in the Southwest, but they still have longer bills than female Scarlet Tanagers. Scarlets usually, but not always, have dusky bills, while Summers usually have pale bills. Scarlets usually have darker wings contrasting with an olive back, while Summers have more brownish upperparts (wings and back). But Scarlets with washed-out plumages showing little wing-back contrast are not unusual; such birds can be identified by bill structure (longer in Summer), by the tones of the back (greenish in Scarlet, brownish in Summer), by the color of the underside of the rectrices (grayer in Scarlet, greenish yellow in Summer), and by patterning in the face: Summer sometimes shows a faint dusky line through the eyes and/or under the eyes, while Scarlet looks plain-faced.
Western and Flame-colored Tanagers Female Western and Flame-colored Tanagers are superficially similar: both have wing bars and are washed with yellow below. But female Flame-coloreds have darker bills; stippled backs, compared to the grayish or olive-gray backs of female Westerns; stronger, very white wing bars, without the yellowish tint of Westerns; and large white spots, rather than pale edges, on the tertials. In Arizona the two have hybridized; the suspected hybrid offspring have shown intermediate characteristics.
145 species: Worldwide. Sixteen species breed in North America.
Finches (family Fringillidae) are small passerines that are sometimes confused with sparrows or buntings; this is particularly the case with the smaller species, which, like the other small, seed-eating passerines, have short, conical bills adapted for feeding on seeds. But finches differ from sparrows in many ways. Most have shorter tails that show a distinct, shallow fork. Finches are usually sexually dimorphic: males are usually brightly colored (brighter than sparrows) in reds, yellows, and rusts, and females and young of the smaller species are often mousy brown above and sometimes streaked below. Finches are more arboreal than sparrows, though most frequent open woodlands and edges rather than closed forests. Finches are often seen high overhead in the morning, in undulating flight; sparrows tend to stay low to the ground, flying overhead mainly during migration, at night.
The nearest relatives of finches are probably the pipits and wagtails (family Motacillidae) and the Old World sparrows (Passeridae), both nine-primaried oscines, like finches. Other nine-primaried oscines--American warblers, tanagers, cardinalids, and icterids--are also probably closely related. Like the cardinalids, the larger finches have heavy, powerful bills. In the crossbills, the maxilla and mandible cross, like misaligned pincers, an adaptation for foraging on pine and spruce seeds.
Courtship among finches consists mostly of persistent singing, courtship feeding, and song flights around the female; females sometimes sing when building the nest, though less vigorously than males. Finches often nest rather close to one another and do not defend territories, but the male does guard the female against other males that approach During their periodic irruptions, finches (such as this female Pine Grosbeak) take advantage of bird-feeding stations and plantings, such as crabapple trees. too closely. After egg-laying, males sometimes form foraging flocks. Long after the young have fledged, the nests of finches are recognizable by their edges, which are covered with the feces of the nestlings; this is not seen in any other passerines except Olive Warbler (Peucedramidae).
|During their periodic irruptions, finches (such as this female Pine Grosbeak) take advantage of bird-feeding stations and plantings, such as crabapple trees.|
Of all North American birds, the "winter finches"--Pine Siskin, Whitewinged and Red Crossbills, Pine and Evening Grosbeaks, and Common and Hoary Redpolls--are best known for their erratic wanderings and winter irruptions; many thousands may move south from the tundra and boreal forest and visit forests and feeding stations, where they can consume large amounts of birdseed. Such influxes are almost certainly the result of poor seed and cone crops in the core range.
The remoteness of their breeding grounds, the apparent stark fluctuations in breeding success, and their irregular movements make it difficult to assess the actual abundance and conservation status of most finches. Evening Grosbeak was quite rare in the East until the 1950s, when the species began nesting east of the Great Lakes in large numbers, apparently in response to a sustained outbreak of spruce budworms in the boreal forest. Its numbers have declined recently; it and Purple Finch are now less numerous in the East than they were a generation ago.
279 species: Worldwide except the Australian region. Fifty-two species breed in North America.
Sparrows in North America include the New World sparrows (family Emberizidae) and the introduced Old World sparrows (Passeridae)--House Sparrow and Eurasian Tree Sparrow--which are distant relatives of Emberizidae. Emberizids are small, mostly brown birds with short, conical bills and moderately long tails. They typically have a straight-edged culmen (upper edge of the maxilla), whereas the passerids have a distinctly curved culmen, especially in males. An exception is White-collared Seedeater, a tiny emberizid whose range barely enters the United States in Texas, which also has a curved culmen. The curve-billed Bananaquit (Coerebidae) is also illustrated here; its relationships to other bird taxa are not well understood, but present research suggests kinship to the grassquits, tropical emberizids that have occasionally strayed to Florida and Texas.
With a few exceptions, sparrows are birds of thickets and open brushy or marshy environments, where both seeds and insects, the mainstays of their diet, abound. A few species are found in open forests. Bill size differs subtly but importantly among sparrows and is a good clue as to the size of seed the species is likely to eat. Towhees and sparrows scratch both feet backward in rapid motion to move leaf litter and other material quickly, exposing insects and other arthropods as well as seeds.
Most sparrows have monogamous mating systems, with males singing to defend a territory and mate. Some are polygynous, notably Lark Bunting and Savannah Sparrow. Saltmarsh Sharp-tailed Sparrow has a very unusual mating system: the male does not defend a territory but wanders widely and attempts to mate with as many females as possible. A few species, such as Henslow's and Clay-colored Dusky Seaside Sparrow of Florida became extinct in the 1980s, a victim of pesticide spraying and loss of wetland habitat. Sparrows and Allies Sparrows, maintain rather small territories (thus they seem almost colonial when habitat is optimal) or show little interest in territorial defense. Most sparrows build a cup-shaped nest of grasses on the ground or in a small tree or bush; a few species cover the cup with a dome of grasses for added concealment.
Conservation concerns for emberizids abound in North America, largely because their habitats--fields and grasslands in particular--have been heavily developed and modified for centuries. Among the most beleaguered species are Henslow's and Baird's Sparrows, which specialize in prairie habitats, and Bachman's Sparrow, a bird of longleaf pine savannas. These ecosystems have lost 97 to 99 percent of their precolonial extent. Conservation action came too late to save the distinctive Dusky Seaside Sparrow, a resident of western Florida marshes classified as a subspecies of Seaside Sparrow (but almost certainly a full species); the last of these birds died in 1987.
Identification of Aimophila Sparrows:
|Botteri's Sparrow||Cassin's Sparrow||Bachman's Sparrow|
Cassin's, Botteris, and Bachman's Sparrows (genus Aimophila) are similar in structure: large, long-tailed, and fairly heavy-billed. Bachman's, identified by its southeastern range and open pinewoods habitat, rarely strays northward. Cassin's and Botteri's Sparrows both inhabit desert grasslands; Cassin's is nomadic, occasionally straying as far out of range as eastern Canada (Botteri's has not been reported out of range). Many Aimophila are heavily worn, and thus difficult to identify, during the breeding season; their song is diagnostic. To identify a silent Aimophila, look at the back, uppetrail coverts, bill, and head. In cassin's, pale fringes on mantle and scapular feathers make the back look scaly; Botteri's and Bachman's show heavy gray and wine-rust streaks on the back. The uppertail coverts of Bachman's and Cassin's have dark subterminal marks; the coverts of Botteri's have long, gark shaft streaks. Botteri's has the largest bill of the three, Cassin's the smallest; Bachmans is in between. Bachman's shows a rust crown and supercillium and ruddy stippling on the nape and sides os the breast. Botteri's has a similar though duskier and weaker head pattern and a very weak submalar mark (but lacks the nape and breast markings). Cassin's has only a weak head pattern, with the crown lightly stippled, but has a clear eye ring and submalar mark in fresh plumage.
37 species: Widespread in the Old World, especially in Africa. Represented in North America by only two species, both of them introduced.
Unlike new world sparrows (emberizids), passerids are generally colonial when nesting; males perform animated courtship displays, hopping around with cocked tail and drooped wings like windup toys. Passerids usually nest in cavities; they will accept virtually any cranny available (often in buildings), constructing a round nest of twigs and grasses within the cavity.Identifying Small Brown Landbirds:
|Song Sparrow||Smith's Longspur||Lazuli Bunting||Purple Finch||House Sparrow|
|Dickcissel||American Pipit||Horned Lark||Red-winged Blackbird||Palm Warbler|
Many small, brownish, sparrow-like passerines from different families are found around the continent in open-country habitats. They can be troublesome to identify, but beginning birders can learn to pin them at least to family and/or genus by noting body and bill shapes, behavior (foraging and locomotion), basic field marks, and vocalizations, especially the songs (covered in individual species accounts). Below is a thumbnail comparison of many types of small, sparrow-like birds that frequent open fields, hedgerows, thickets, and other edge habitats. (See also "Small Woodland Birds," which covers mostly arboreal species.)
Sparrows are small birds with conical bills that forage on or near the ground for seeds and insects; most are streaky brown above and paler below; some have streaks on the under parts. Their bills vary from short and delicate (Brewer's) to long and heavy (Seaside and Botteri's). Most areas have more than a dozen species, some of which remain in dense vegetation most of the time. In winter different species often flock together, flushing ahead of an observer, then diving quickly back into cover, which makes identification challenging.
Longspurs and their relatives the Plectrophenax buntings (Snow and McKay's) are short-legged, plump sparrows of open habitats such as tundra, shortgrass prairies, and beaches. Longspurs, named for the elongated nail on the hind toe, are rather heavy-billed for their size, and all four have white in the outer rectrices. Like larks, pipits, and Snow Bunting, longspurs frequent farm fields in the non-breeding season to forage for seeds, sometimes in mixed flocks.
Finches are often mistaken for sparrows; the smaller, sparrow-sized finches have conical bills, like those of sparrows, and some finches (Pine Siskin, female Purple, Cassin's, and House Finches, female redpolls) are brown above and streaky below like sparrows. The bills of finches differ: the siskins' bills are rather slender and finely pointed; redpolls' bills are very short and delicate; bills of Purple and House Finches have a subtle curvature in the culmen. Rosy-finches have very sparrow-like bills but usually show some rosy coloration in the plumage, unlike sparrows. Finches, other than the rosy-finches, are also usually more arboreal than sparrows; they tend to cling to weedstalks when feeding rather than perch on the ground, as sparrows often do. When flushed, finches usually fly up to the top of the vegetation but rarely fly into dense cover.
Female buntings of the genus Passerina are often mistaken for sparrows because of similar bill shape and brown plumages. While the bills show only subtle differences from the bills of sparrows, their plumages are much plainer, with little or no pattern in the wings and back.
Old World sparrows are represented in North America by introduced House and Eurasian Tree Sparrows. Males are distinguished form the New World sparrows by their bills, which have curved culmen. Female House Sparrow has a more conical bill and rather plain plumages similar to New World sparrows.
Dickcissel, when seen hopping among House Sparrows at a feeder, could easily be overlooked, especially as young female, which in plumage resembles a female House Sparrow. Dickcissel has a heavier bill, however, and usually has a thing submalar mark and sometimes faint streaking below.
Blackbirds are a diverse group; with exception of the meadowlarks, most have slender bodies, moderately long tails, and rather long bills that are heavier at the base. Only a few members of the family are regularly confused with sparrows. Bobolink has a deeper, more sparrowlike bill than larger blackbirds, and females and nonbreeding birds are quite sparrowlike; their richer colors and stronger plumage contrasts help to distinguish them from sparrows. Red-winged and Tricolored Blackbird females are streaky below, like sparrows, but their bills are much longer.
Pipits in North America are thin-billed terrestrial birds found in a wide variety of open habitats, from tundra to desert to lakeshores. Their plumage is sparrowlike, but their bodies and especially bills are much more slender. In agricultural fields, flocks of American Pipits amble actively back and forth, picking seeds and insects. Sprague's Pipit does not flock.
Horned Lark can also often be found in agricultural fields. Like pipits, this species forages for seeds and can form large flocks. It is readily identified by its distinctive face pattern. Though larks have rather long legs, like pipits, they often feed more closely crouched to the ground, using a creeping shuffle more like that of the longspurs. Their bills are slimmer than those of longspurs but heavier and shorter than those of pipits.
Warblersare typically arboreal, but several species (Pine, Palm, and Yellow-rumped Warblers) regularly forage on the ground in open environments. Some of these are very plain brown above and paler below with a few streaks, rather like sparrows; in all cases their thin bills give them away.
Wrensalso frequent field edges, where they stay mostly in thickets; their thin, often long bills, mottled plumages, and often cocked tails separate them easily from true field birds.
65 species: Primarily an Old World family; only two species breed in North America south of Alaska. These two are the widespread American Pipit and the localized Sprague's Pipit of the Great Plains.
Wagtails and pipits (family Motacillidae) and larks (Alaudidae) are only distant relatives, but they share habitat preferences, foraging strategies, and some structural and behavioral features. All are small to medium-sized, rather slim passerines that walk through shortgrass fields and other open habitats, often in groups, to feed on insects and seeds. They have strong legs, sometimes with elongated hind claws. All are ground-nesters, monogamous, and highly migratory. Motacillidae and Alaudidae are mainly Old World families: only two species of lark and four motacillids breed on this continent.
Wagtails are larger than pipits and have longer tails, which they constantly wag, and striking plumages. They are conspicuous, active foragers, chasing insects on the ground, flycatching, and even taking invertebrates in streams. Pipits forage less actively, usually walking erratically through fields. Larks and pipits perform splendid song-flight displays. American Pipit and Horned Lark form large flocks, often in association with longspurs and Snow Buntings, in the non-breeding season. Pipits and larks have shown local declines in both wintering and breeding populations. Declines in Sprague's Pipit have been most severe.
91 species: This almost exclusively Old World family is represented in America by one native species, the Horned Lark, and by the Eurasian Skylark ( Alauda arvensis ) introduced in British Colombia.