Adult little blue herons are slate blue with dark, greenish legs and a two-colored bill having a blue base and a dark tip. If the bird is in good light, its head and neck appear grayish maroon or purplish; in poor light, the bird simply appears dark.
First-year immatures are all white but have the same bill coloration (blue base and dark tip). As they mature during the second year, they gradually molt to the adult plumage, and blue-gray patches appear on the white plumage, giving them a spotted, mottled, or "calico" appearance.
The voice is a low bark; during courtship, it is a noisy chatter or jumbled rattle.
Similar species: Because first-year immature little blue herons are all white, and they are the same size as the snowy egret, the two are frequently misidentified as each other. However, the snowy egret has an all-dark bill; also, the little blue heron has greenish/dark legs, while the snowy egret has black legs with yellow feet. Also, the little blue heron has the patch in front of the eye gray (not yellow or reddish as in the snowy egret).
In general appearance (shape and coloration), an adult little blue heron somewhat resembles the great blue heron, except that the little blue heron is about half the size of the latter.
Length: 24 inches (tip of bill to tip of tail).
Potentially statewide, especially during migration. Nesting colonies are primarily in the Mississippi Lowlands.
Habitat and Conservation
Forages in a wide variety of marshes and wet, low ground. Nesting colonies are usually in clusters of small trees and shrubs in wetlands, though sometimes in upland sites.
Food
Like other small herons, the little blue heron preys on small fish, frogs, crayfish, and a wide variety of insects.
Herons capture their prey with a quick lunge, grasping their prey with their bill and swallowing it headfirst. Often, the heron wades slowly, stirring the mud on the bottom, trying to capture small animals fleeing the disturbance.
Status
A species of conservation concern in Missouri, considered vulnerable to extirpation from the state. However, in other parts of its range, the species is considered of low conservation concern.
Locally common summer (breeding) resident in southeast Missouri. Elsewhere in the state, uncommon as a transient and summer (nonbreeding) visitor.
The entire North American population of little blue herons declined by about 50 percent between 1966 and 2019. Some of the reasons for the decline include changes in water drainages and loss of wetlands, declining water quality, consumption of prey contaminated by toxins, including heavy metals, and human disturbance at colonies during breeding season.
Life Cycle
Little blue herons are present in Missouri from the beginning of April through the end of September. In Missouri, most of their breeding colonies are in the Bootheel lowlands.
Little blue herons frequently nest in crowded, mixed-species breeding colonies, where other species of herons are also nesting. Each nest is a loose platform, about a foot in diameter, built of sticks and twigs.
Clutches comprise 3 or 4 eggs, which are incubated for about 22 days. After hatching, the young remain in the nest for 35 to 49 days before fledging.
A little blue heron can live to be at least 13 years old in the wild.
Human Connections
If you discover a heron breeding colony, don’t approach it; instead, use binoculars or a telescope. It is important to remain a good distance away from a heron colony, for your health and theirs:
- When disturbed, the young may easily fall from the rather flimsy nests their parents build and can drown. Adults may take flight and collide with branches or one another; wings are easily broken and nestlings abandoned.
- Also, entering an area where many birds are concentrated together raises your risk of contracting histoplasmosis, a respiratory disease caused by the airborne spores of a fungus associated with bird droppings.
During the early 20th century, many herons and egrets were overhunted to the point where they nearly went extinct. Little blue herons, however, survived in part because they lack they long head plumes that people coveted for hat decorations; their scalps weren’t worth much to the plume hunters. By the 1930s, inexperienced birders would see an all-white juvenile little blue heron and get excited, thinking they were seeing the then very rare snowy egret.
The species name, caerulea, means “blue.” In the past, one of the common names for this bird was “blue crane.”
Ecosystem Connections
A variety of predators may prey on little blue herons, especially on the nestlings and eggs. These include raccoons, snakes, and even other herons. In Florida, nonnative, invasive pythons, boa constrictors, and other snakes prey on heron colonies, as well.
- One hypothesis for colonial nesting is that it can help reduce predation: first, by having so many alert parents to discover and raise the alarm about an approaching predator; second, by having so many individuals together, it lessens any single individual’s chances of being the one that is eaten.
One of the ways to distinguish young little blue herons from snowy egrets is that the little blue walks and moves more slowly and deliberately, while the snowy egret typically moves more quickly.
- Whenever two species are foraging for more or less the same foods in the same place, they frequently have some foraging strategy that helps them find foods the other misses. It could be a slightly different place where they’re looking for food, or focusing on slightly different types of prey than the other, or a different way of capturing the food.
- The slower movements of the little blues may help them find foods the snowies pass over, while the snowies' quick movements may help them snatch up foods the little blues can't get. Indeed, biologists have noted that although both species eat small fishes, the little blue captures fish that are larger than those the snowy usually eats.
The genus name, Egretta, means “little egret” or “little heron.” The genus is found around the world. Other birds in this genus include the snowy egret as well as two other North American species you might see if you travel to the Caribbean or to Florida or other Gulf Coast states: the reddish egret and the tricolored heron. The reddish egret, in particular, strongly resembles the little blue heron.
About 350 species of birds are likely to be seen in Missouri, though nearly 400 have been recorded within our borders. Most people know a bird when they see one — it has feathers, wings, and a bill. Birds are warm-blooded, and most species can fly. Many migrate hundreds or thousands of miles. Birds lay hard-shelled eggs (often in a nest), and the parents care for the young. Many communicate with songs and calls.