Little Blue Heron Life History

Habitat

Little Blue Herons nest and forage in many kinds of wetlands, including swamps, marshes, ponds, streams, lagoons, tidal flats, canals, ditches, fish hatcheries, and flooded fields. They nest mostly in shrubs and small trees in standing water or upland sites on islands, including artificial islands created from dredged material. Rarely, they seek prey in upland pasture sites. They usually forage in water 2–6 inches deep, often gravitating toward densely vegetated foraging sites. In wintertime, Little Blue Herons make especially frequent use of mangroves, lagoons, salt ponds, mudflats, and savannas. Back to top

Food

Little Blue Herons eat mostly small fish, supplemented by a variety of small amphibians as well as crustaceans, grasshoppers, dragonflies and other invertebrates. Types of fish prey vary by region, and may include anchovies, killifish, gobies, perch, darters, bass, minnows, carp, and others. Invertebrate prey may include crayfish, prawns, isopods, crabs, and a wide variety of insects.Back to top

Nesting

Nest Placement

Little Blue Herons nest in low shrubs and small trees, in protected areas below the canopy. They may also choose flooded areas or islands as added protection against predators. Little Blue Herons and neighboring colonial birds have a pronounced impact on their nesting habitat—stunting the growth of vegetation by harvesting nest material and sometimes killing trees outright by the accumulation of guano.

Nest Description

After pairing up, a male and female spend 3–5 days building a porous platform nest of long, mostly leafless twigs and sticks lined with greener vegetation. Usually the male finds nesting material and passes it to the female, who constructs the bulk of the nest; he occasionally assists her, or performs ritual twig-shaking displays nearby. The nest has an outside diameter of 1–1.5 feet.

Nesting Facts

Behavior

Little Blue Herons forage by wading up to their bellies in freshwater, brackish, or saltwater wetlands, with their necks extended stiffly forward and bills tilted down, occasionally swaying the head and neck as they size up their prey. Little Blue Herons often forage with other species, and they are gregarious breeders, nesting in multispecies colonies alongside ibises, Brown Pelicans, Tricolored Herons, and other waterbirds. They may chase and attack other members of their own species in defense of food or nesting territory, striking and jabbing at each other with their bills. Little Blue Herons fly with slow, steady wingbeats, usually with neck and head pulled back against the body. A courting male points his bill straight upward, suddenly extending and retracting his neck. Little Blue Herons of both sexes, when courting, may occasionally grasp, pull, and shake branches while simultaneously erecting the feathers along their head, neck, and back. Nestling Little Blue Herons, along with many other waterfowl, compete fiercely for the food their parents bring back. In lean years, the older chicks may attack and sometimes kill their younger, smaller nestmates to claim the food for themselves—a behavior known as siblicide. Back to top

Conservation

Little Blue Heron populations declined by over 1% per year for a cumulative decline of about 49% between 1966 and 2019, according to the North American Breeding Bird Survey. Partners in Flight estimates the global breeding population at 1.1 million and rates them 11 out of 20 on the Continental Concern Score, indicating a species of relatively low conservation concern. The North American Waterbird Conservation Plan lists Little Blue Herons as a species of High Concern that are known or thought to be declining and have other known or potential threats. Habitat loss and human-caused changes in local water dynamics pose the most serious threats to regional populations. The Migratory Bird Treaty Act as well as state wildlife laws protect herons from harassment, killing, or collecting. However, Little Blue Herons that forage at fish hatcheries are vulnerable to illegal shooting; and the U.S. Fish and Wildlife Service and some states issue permits to legally shoot them. Like all waterbirds, Little Blue Herons are vulnerable to changes in water quality. Birds that eat prey from flooded agricultural fields and drainage ditches risk contamination from pesticides and heavy metals. Human disturbance has also been shown to harm colonial breeding bird populations, causing adults to abandon nests, eggs and chicks to die, and other impacts. Closing wading-bird colonies to human disturbance during the breeding season can help protect Little Blue Herons.

Credits

Ehrlich, P. R., D. S. Dobkin, and D. Wheye (1988). The Birder's Handbook. A Field Guide to the Natural History of North American Birds, Including All Species That Regularly Breed North of Mexico. Simon and Schuster Inc., New York, NY, USA.

Kushlan, J. A., M. J. Steinkamp, K. C. Parsons, J. Capp, M. A. Cruz, M. Coulter, I. Davidson, L. Dickson, N. Edelson, R. Elliott, R. M. Erwin, S. Hatch, S. Kress, R. Milko, S. Miller, K. Mills, R. Paul, R. Phillips, J. E. Saliva, W. Sydeman, J. Trapp, J. Wheeler and K. Wohl (2002). Waterbird conservation for the Americas: The North American waterbird conservation plan, version 1. Washington, DC, USA.

Lutmerding, J. A. and A. S. Love. (2020). Longevity records of North American birds. Version 2020. Patuxent Wildlife Research Center, Bird Banding Laboratory 2020.

Partners in Flight. (2020). Avian Conservation Assessment Database, version 2020.

Rodgers Jr., James A. and Henry T. Smith. (2012). Little Blue Heron (Egretta caerulea), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2019). The North American Breeding Bird Survey, Results and Analysis 1966–2019. Version 2.07.2019. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

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