The little blue heron is part of the family Ardeidae, a group whose members can be found throughout much of the world, including the Americas, Africa, Asia, and Oceania.

[2] Young birds found in a little blue heron nest in North Dakota, at a site heavily populated by cattle egrets (Bubulcus ibis), which displayed traits of both the former and latter, are believed to be an example of hybridization between the two species.

Immature birds transitioning from the juvenile to adult phase have a combination of light and dark feathers.

[9] The eggs are typically smooth, light blue, and unmarked, measuring about 31.7–43.2 millimetres (1.25–1.70 in), and weighing around 23.1 grams (0.81 oz).

[10] Egretta caerulea can be found regularly in the United States, Mexico, Central America, northern South America (including Venezuela, Colombia, and Peru), and numerous Caribbean islands (including Cuba, Jamaica, and Hispaniola).

They have been recorded as a vagrant (a species that appears far outside its natural range) in Greenland, Portugal, and South Africa.

[3] One study found that of seven migratory wading bird species, the little blue heron had the greatest mean dispersal distance, of 1,148 kilometres (713 mi).

If global warming continues at its current rate, by the year 2080, its summer range will have increased by 87%.

These gains would spread its summer distribution well into more northern parts of the US, such as Michigan and Minnesota, and even into southern Canada.

These include mangrove forests, bogs, swamps, salt marshes, tidal flats, estuaries, streams, and flooded fields.

[5] Towards the southern extent of their range, in Brazil, they are found almost exclusively along the coast, rarely venturing inland at all.

[10] Twenty-four different species of parasitic worms were found on 33 of 35 little blue herons examined in South Florida.

[15] On the eastern coast of North America, little blue herons primarily feed on fish, however their diet varies significantly throughout their range.

[9] In a study of individuals in mangrove forests in southeastern Brazil, 80% of their diet during the breeding season was found to consist of crabs.

This demonstrates their different feeding strategies—scarlet ibises being foragers who hunt using their sense of touch and little blue herons being visual hunters.

[16] In another mangrove forest in southwestern Puerto Rico, the entire diet was found to consist of fiddler crabs.

[17] The little blue heron is listed as a least-concern species by the International Union for the Conservation of Nature, although its numbers are decreasing.

[1] Historically, they were not hunted for their feathers as much as other heron species due to their lack of visually attractive plumes.

[18] In Sepetiba Bay, Rio de Janeiro, Brazil, little blue herons were found to have relatively high levels of metal contamination in the liver and kidneys.

[19] In areas with cattle egrets, little blue herons have been found to nest for shorter amounts of time, and produce fewer young that survive to adulthood.

Cattle egrets only begin pairing when most little blue herons already have eggs or live young in their nests.