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Little Blue Heron

Egretta caerulea ORDER: PELECANIFORMES FAMILY: ARDEIDAE

IUCN Conservation Status: Least Concern

A small, dark heron arrayed in moody blues and purples, the Little Blue Heron is a common but inconspicuous resident of marshes and estuaries in the Southeast. They stalk shallow waters for small fish and amphibians, adopting a quiet, methodical approach that can make these gorgeous herons surprisingly easy to overlook at first glance. Little Blue Herons build stick nests in trees alongside other colonial waterbirds. In the U.S., their populations have been in a gradual decline since the mid-twentieth century.

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At a GlanceHelp

Measurements
Both Sexes
Length
22–29.1 in
56–74 cm
Wingspan
39.4–41.3 in
100–105 cm
Weight
10.4–14.5 oz
296–412 g
Relative Size
Smaller than a Great Blue Heron; about the size of a Snowy Egret.
Other Names
  • Petit héron bleu, Aigrette bleue, Crabier bleu (French)
  • Garza azul, Garceta azul (Spanish)

Cool Facts

  • During the feathered-hat fashion craze of the early twentieth century, Little Blue Herons’ lack of showy “aigrette plumes” saved them from the hunting frenzy that decimated other heron and egret populations.
  • Little Blue Herons may gain a survival advantage by wearing white during their first year of life. Immature birds are likelier than their blue elders to be tolerated by Snowy Egrets—and in the egrets’ company, they catch more fish. Mingling in mixed-species flocks of white herons, immature Little Blue Herons probably also acquire extra protection against predators.
  • With their patchy white-and-blue appearance, Little Blue Herons in transition from the white first-year stage to blue adult plumage are often referred to as “Calico,” “Pied,” or “Piebald.”
  • When observing groups of white herons and egrets foraging together, look for the slow, deliberate movements of an immature Little Blue Heron. This stately and deliberate pace helps distinguish the Little Blue Heron from its relatives, which tend to move more quickly or erratically.
  • A row of built-in “teeth” along the Little Blue Heron’s middle toe serves as a grooming comb. The bird uses this handy tool to scratch its head, neck, and throat.
  • The longest-lived Little Blue Heron on record was 13 years and 11 months old, and was banded in Maryland.

Habitat


Marsh

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.

Food


Fish

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.

Nesting

Nesting Facts
Clutch Size
3–4 eggs
Number of Broods
1 broods
Egg Length
1.6–2 in
4.1–5.1 cm
Egg Width
1.2–1.4 in
3.1–3.6 cm
Incubation Period
22–23 days
Nestling Period
35–49 days
Egg Description
Pale bluish green.
Condition at Hatching
Hatchlings are covered with sparse white down, eyes partially open.
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.

Nest Placement

Tree

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.

Behavior


Stalking

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.

Conservation

status via IUCN

Least Concern

Little Blue Herons are fairly common and have a large range in North and South America. However, their numbers showed a gradual decline between 1966 and 2010, according to the North American Breeding Bird Survey. The North American Waterbird Conservation Plan considers Little Blue Herons a species of High Concern owing to declining populations. 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 by 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

Range Map Help

Little Blue Heron Range Map
View dynamic map of eBird sightings

Migration

Resident to medium-distance migrant. Birds that breed in the interior Southeast migrate to Central and South America and the Caribbean; individuals along the Gulf Coast, Florida, and elsewhere disperse only short distances.

Find This Bird

Scan the edges of shallow water, particularly where there is adjacent emergent vegetation or overhanging bushes or trees, for this fairly inconspicuous heron. You’ll typically see them only in ones and twos, although they may gather with other herons and egrets, particularly at times when a school of small fish has become trapped in shallow water. In open, marshy habitats you may also see Little Blue Herons flapping slowly on rounded wings across the sky. Little Blue Herons often nest with other waterbirds, so if you can find an active colony, scan through the incoming and outgoing birds for small herons with completely dark plumage.