Olive-sided Flycatcher

Contopus borealis

Peter LaTourrette
  • Tyrant-flycatchers
  • 1.2 million

Often found perched on top of a large tree or snag, Olive-sided Flycatchers are an easily recognized breeder of North America's coniferous forests. They perform one of the longest migrations of the Nearctic migrants, and are typically known as late arrivals in the spring and early migrants in the fall. Although their breeding range is quite expansive, their low density and significant declines over the past 30 years have caused them to be listed as a Sensitive Species or Species of Concern by several state and federal agencies and conservation groups.

Olive-sided Flycatchers, both male and females, are stout, block-headed, short-tailed birds with a large bill. The back is olive-gray-brown, with similar colored streaked sides. These colored sides, along with dull white stretching from the throat down to the belly, give the appearance of an "unbuttoned vest" on the underside. Looking carefully, one can sometimes find pure white tufts poking from behind the wings above the rump. Its loud song, generally depicted as "quick, THREE BEERS!" is easily recognizable.

Distribution and Population Trends
The Olive-sided Flycatcher's breeding range is widespread across North America, stretching from western Alaska across Canada to the Maritime provinces, south to Minnesota, Michigan, Ohio, New York, and western Massachusetts. The breeding range extends south from Canada through many of the western United States, extending as far south as the mountains of southern California. They can be found throughout the Rocky Mountains south to the Mogollan Rim in Arizona and the Sangre de Cristo Mountains of New Mexico. In the eastern states, it is a local breeder in the high Appalachians south to Tennessee and North Carolina. Winters primarily in the Andes Mountains of South America, with small numbers in Central America and southern Mexico.

Breeding Bird Survey (BBS) trend analyses show a significant rangewide decline of 3.3% per year from 1966-2001. BBS data also show the highest abundances of Olive-sided Flycatchers are in western North America where the declines are steepest.

Olive-sided Flycatchers undertake the longest migration of any of North America's flycatchers, arriving on their breeding grounds late in the spring. Though Olive-sided Flycatchers use a diversity of habitats during migration, including nonconiferous and riparian areas, they mainly use mountain habitats.

Birds arrive in the southern portion of their breeding range as early as mid-April, but more typically in early May. Northern portions are reached in mid- to late-May. Preferred habitat consists of mid- to high-elevation montane and coniferous forests, often associated with forest openings and edges. Presence in early successional forests appears to depend on availability of snags or live trees that provide suitable foraging and singing perches. It is frequently found along wooded shores of streams, lakes, rives, beaver ponds, bogs and muskegs, where natural edge habitat occurs and standing dead trees often are present. Females choose nest site usually in a coniferous tree, although sometimes in trembling aspen and willow. The female incubates the single brood for 15-19 days, during which the male may bring food to female on nest, particularly during early incubation. Little is known about the nestling period, other than it typically lasts between 15 - 19 days.

Olive-sided Flycatchers are a passive sit-and-wait predator, perching on a prominent limb until an insect sighted, then actively pursuing it. Their prey is almost exclusively flying insects, including bees, wasps, and flying ants, along with flies, moths, grasshoppers, and dragonflies. They almost entirely sally for aerial prey, although other flycatchers may attack insects by pouncing on prey on the ground.

Known as an early fall migrant, birds start leaving the northern portion of the breeding range by early August, most have left their breeding grounds throughout their range by mid- to late-September.

Although numerous studies report a positive response to some types of harvested forest in the United States and Canada, Olive-sided Flycatchers have experienced precipitous population declines in nearly every region of its breeding range. These declines may likely be due to major deforestation on its wintering grounds. Additionally, it has been speculated that Olive-sided Flycatchers historically depended on postfire habitats, so it has been proposed that harvested forests may actually be an ecological trap: while they look similar to a post-burn forest, they may function quite differently. A preliminary study seems to support this hypothesis, but more studies are needed. Little is known about the effects of pesticides especially those commonly used to control insect outbreaks on industrial forests land within the boreal forest.

Although little conservation work has been directly focused on Olive-sided Flycatcher, various groups are carrying out conservation work that will likely be beneficial. For example, a coalition has begun working together to achieve a vision of protection and sustainable use of the Canadian boreal forest. Fulfillment of this vision will be important in the long-term health of Olive-sided Flycatcher populations. Audubon New York's Forest Biodiversity Stewardship Program is developing landowner outreach and educational materials for how private forest landowners can manage for Olive-sided Flycatcher and other forest-dependent species through various forestry techniques. To find out more visit: http://ny.audubon.org/FOREST/index.html

What Can You Do?
Audubon's Important Bird Areas program is a vital tool for the conservation of Olive-sided Flycatchers as well as other species. To learn more about the Important Bird Area programs and how you can help, visit: http://www.audubon.org/bird/iba/.

Information on where Olive-sided Flycatchers occur and in what numbers is vital to conserving the species. Help in monitoring this and other species by reporting your sightings to eBird. A project of Audubon and the Cornell Lab of Ornithology, eBird is the world's first comprehensive on-line bird monitoring program: http://www.audubon.org/bird/ebird/index.html

Support local land trusts, government agencies, and other organizations working to preserve habitat in your area. Contact your state Important Bird Areas coordinator (http://www.audubon.org/bird/iba/state_coords.html) to find out if there are sites in your area important for Olive-sided Flycatcher that need increased protection.

U.S. National Wildlife Refuges provide essential habitat for Olive-sided Flycatcher, and a great number of other species throughout the U.S. and its territories. Unfortunately, the refuge system is often under-funded during the U.S. government's budgeting process. To learn more about how you can help gain much needed funding for U.S. National Wildlife Refuges, visit: http://www.audubon.org/campaign/refuge_report/

Audubon and our partners in conservation coordinated the submission of over two million comments to the U.S. Forest Service in support of the Roadless Area Conservation Rule, which would protect habitat for Olive-sided Flycatcher and many other species. Unfortunately, implementation of the Rule has been stalled and attempts are being made to weaken it. To help in protecting these vital habitats visit: http://www.audubon.org/campaign/latestnews.html#roadless

The Canadian Nature Federation and Bird Studies Canada, Audubon's BirdLife partners in Canada, jointly administer an Important Bird Areas program that is working to identify and protect habitat for Olive-sided Flycatchers and many other species. To learn more visit: http://www.ibacanada.com/.

Audubon is the U.S. representative of the global BirdLife International alliance. Our BirdLife partners in Central and South America are developing Important Bird Areas programs to identify and conserve critical habitats that support Olive-sided Flycatcher and many other species. For more information on BirdLife IBA efforts throughout the Americas visit: http://www.birdlife.net/sites/index.cfm

The Cornell Lab of Ornithology and the USDA Forest Service coordinate Birds in Forested Landscapes, a citizen-science project that links volunteer birders and professional ornithologists in a study of the habitat requirements of North American forest birds, including Olive-sided Flycatcher. To learn more about Birds in Forested Landscapes, and how you can participate in the project, visit: http://birds.cornell.edu/bfl/

Altman, B., and R. Sallabanks. 2000. Olive-sided Flycatcher (Contopus cooperi). In The Birds of North America, No. 502 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.

Birds in Forested Landscapes Species Account: Olive-sided Flycatcher (Contopus cooperi). Cornell Lab of Ornithology. http://birds.cornell.edu/bfl/speciesaccts/olsfly.html