Little Blue Heron

Egretta caerulea

Manjith Kainickara. Creative Commons license BY-SA
  • ARDEIDAE
  • Herons, Bitterns, Egrets
  • Ciconiiformes
  • Garza azul, Garceta azul
  • Petit héron bleu, Aigrette bleue, Crabier bleu
Introduction
In the shallows of marine and freshwater marshes, where water and vegetation meet, the Little Blue Heron stalks. Named for its slate blue plumage, the Little Blue Heron blends in well with dark marsh plants. However, these birds are white for their first year, associating with other white egrets that feed in open habitats.
Fun Fact

The Little Blue Heron’s middle toe has “teeth” along one side and is used as a comb to scratch its upper neck, throat, and top and sides of head.

Laura Erickson
Bird Sounds
© Lang Elliot, Nature Sound Studio
Vocalization

Not very vocal, except during courtship. During aggressive encounters, a loud nasal "skaa" call.

Appearance Description
On average, Little Blue Herons measure 24 inches in length with a 40-inch wingspan, and weigh about 12 ounces—one-sixth the mass of a Great Blue Heron. Little Blues appear dark overall, with a relatively stout neck, moderately long, yellow-green legs, and a dagger-shaped, slightly drooped blue bill with a black tip. The entire body below the upper neck is slate blue. A purplish maroon color, boldest in summer, adorns the head and neck. Sexes are alike. First year birds begin their lives completely white and are difficult to distinguish from juvenile Snowy Egrets. After about nine months, grayish feathers begin to molt into the white plumage, creating a remarkable splotched appearance.
Range Map
Courtesy Kenn Kaufman
Range Distribution
Little Blue Herons breed along the Atlantic coast from southern Maine to Florida, with concentrations from South Carolina southward. Breeding across the Florida peninsula, this egret is distributed unevenly around the Gulf Coast and coastal plain, with the greatest densities in Louisiana. Little Blue Herons also breed up the Mississippi River valley into Illinois and through eastern Texas into Kansas. Wintering territory shrinks back to the warmer coasts. Little Blue Herons also occur throughout the Caribbean, Central America, and South America as far south as Uruguay.
 
A legend for the range map to the right can be found here.
Habitat
Little Blue Herons nest in small trees, shrubs, and mangrove stands near or over water. Estuaries, saltwater and freshwater marshes, and river bottoms are used for feeding and breeding. This heron forages in marshes, lagoons, canals and ditches, impoundments, ponds, streams, and flooded fields, usually where vegetation is emerging or mature. Young Little Blue Herons prefer more open, shallow water. Wintering habitat is similar.
Feeding
This dark, deliberate stalker walks, pauses, crouches, and stares to find prey. Its diet includes small amphibians; small fish such as anchovies, drum, and killifish; crustaceans such as crayfish and crabs; and insects such as bees, dragonflies, flies, and grasshoppers. This heron often forages alone, but juvenile, white Little Blue Herons often join Snowy Egrets to forage in open waters.  
Reproduction
In colonies with other herons, ibises, and Anhingas, Little Blue Herons usually nest in short trees and tall shrubs. Males form small territories, three to six feet wide, and begin to build nest platforms. The most common display is the "neck stretch," in which the male elongates his body upward, then collapses down with bill still up but neck folded, wings opened, and legs bent. A soft "unh!" punctuates the display. Pair bonds last for the season. The male gathers twigs and passes them to the female, who constructs the loose nest, with few or no leaves. Both sexes incubate up to six blue-green eggs for about 22 days, then brood, feed, and defend the white hatchlings together.
 

Little Blue Heron hatchlings can barely raise their heads and must pick regurgitated food from the nest floor for a few days before they can take food directly from the adults. Young birds leave the nest in about five weeks, but return to roost at night after foraging with other white herons.
They disperse from their natal area before migrating in mid-fall.

Migration
After breeding, Little Blue Herons disperse in all directions, but favor the north. Pushed southward by cooler temperatures, usually in late September, this bird migrates via traditional routes along rivers and coasts, with frequent stops to forage and roost. Southern populations move as far south as Central America, and immature birds often remain there through the next year. Spring migrants appear along the mid-Atlantic coast in late March. Southern breeders are essentially residents.
  • 150,000
  • 150,000
  • 150,000 now, 330,000 40 years ago
  • 54 percent in 40 years
  • declining population; high threats
Population Status Trends
With little historical data, long-term population trends for Little Blue Herons are difficult to determine. Between 1966 and 2003, Breeding Bird Survey data indicate fairly stable numbers overall, with increases along the mid-Atlantic Coast and in parts of Mississippi, Arkansas, and the Midwest; however, compensating losses occurred in almost every other state. The Little Blue Heron is a species of conservation concern in Florida, North Carolina, and Virginia. Kentucky's State Nature Preserves considers it endangered, and Mississippi lists it as warranting "timely conservation action."
Conservation Issues
Lacking the breeding plumes most coveted by feather hunters in the 1800s, Little Blue Herons avoided the extensive slaughter of other egrets. The Migratory Bird Treaty Act of 1918 put an end to the millenary trade—and to the losses of these beautiful birds.
 
Today, the loss of feeding habitat seems to be the greatest limiting factor for this dark heron. Between 1780 and 1980, key breeding and wintering states like Mississippi, Arkansas, and Florida lost over 50% of their wetlands. Despite the recent preservation of key breeding sites like Florida's Pelican Island and Ding Darling National Wildlife Refuge, the Little Blue Heron has not shown significant population increases. As a result of farmland expansion, residential development, and recreation, changes in water levels and flow have degraded coastal and riparian wetlands for breeding and wintering herons. Refuge managers now work to maintain open wetland habitats, which first year Little Blues use. A few states limit human proximity to sensitive breeding and foraging areas, but additional public education and buffer zones are needed.
What You Can Do
Join a local nature walk to look for the sometimes elusive Little Blue Heron. Viewing platforms overlooking marshes provide the best views.
 
Attend a wildlife festival where Little Blue Herons are likely to be seen: the Space Coast Birding & Wildlife Festival in Titusville, Florida; or the Pelican Island Wildlife Festival outside Sebastian, Florida.
 
Intrusions near rookeries and foraging areas disrupt reproduction and feeding. Keep a 100-meter buffer zone between yourself and Little Blue Heron nesting sites.
 
Volunteer to conduct a Breeding Bird Survey and help researchers better understand Little Blue Heron population trends.
 
For more actions you can take, including Audubon activities, please visit our resources page.
More Information
Visit our resources page for more information about this species.
Natural History References
Kaufman, Kenn. Lives of North American Birds. Houghton Mifflin Company, New York, 1996.
 
Rodgers, J. A., Jr., and H. T. Smith. 1995. Little Blue Heron (Egretta caerulea). In The Birds of North America, No. 145 (A. Poole and F. Gill, Eds.). The Academy of Natural Sciences, Philadelphia, and The American Ornithologists' Union, Washington, D.C.
 
 
Sibley, David Allen. The Sibley Guide to Birds. Alfred A. Knopf, New York. 2000.
Conservation Status References
Burger, Joanna and Michael Gochfeld. "Effects of ecotourists on bird behaviour at Loxahatchee National Wildlife Refuge, Florida." Environmental Conservation 25 (1998) 13-21. Cambridge 10 May 2002.
 
Dahl, Thomas E. Wetlands: Losses in the United States 1780's to 1980's.  U.S. Department of the Interior, Fish and Wildlife Service, Washington, D.C., 13 pages.
 

 

Kaufman, Kenn. Lives of North American Birds. Houghton Mifflin Company, New York, 1996.
 
Rodgers, J. A., Jr., and H. T. Smith. 1995. Little Blue Heron (Egretta caerulea). In The Birds of North America, No. 145 (A. Poole and F. Gill, Eds.). The Academy of Natural Sciences, Philadelphia, and The American Ornithologists' Union, Washington, D.C.
 
 
Sibley, David Allen. The Sibley Guide to Birds. Alfred A. Knopf, New York. 2000.
 

Trocki CL, Paton PWC. "Assessing habitat selection by foraging egrets in salt marshes at multiple spatial scales." Wetlands 26:2 (2006) 307––312.