Despite being called a heron, these birds seems to be close relatives of the Snowy egret. They look much like them when they are young, but molt to a slate-blue color as an adult. They are generally wary and so are hard to approach. They nest in colonies, sometimes with just their own species. When they are large mixed heronries, the Little blues are usually found nesting along the edges. Several of the largest colonies are located in the lower part of the Mississippi Valley, where these birds often nest together with Cattle egrets.
Inhabiting much of the Americas, this species is found from southern California and in the south-eastern part of the US to Central Brazil and Peru. Outside of the mating season it may travel as far to the north as Canada. Despite the Little Blue heron often living near saltwater, it is mainly an inland bird. It prefers freshwater areas like ponds, lakes, swamps, marshes, and lagoons, but sometimes also occupies flooded and dry grasslands, and marine coastlines.
The Little Blue heron cannot be described as an energetic bird. It will sometimes walk quickly, or even run, but usually it walks slowly and daintily around marshes. While hunting it is a solitary bird, but it nests together with others in a small or large colony. This bird feeds during the day, when its long legs allow it to wade in the water and walk slowly to find prey, often standing motionless or retracing its steps. It uses its foot to rake the ground to disturb prey, stretching its neck so it can peer into the water. The prey is caught with its long bill. Juveniles regularly forage with snowy egrets, as an individual tends to catch more fish if foraging alongside these birds. This unusual strategy for feeding is believed to increase the juvenile’s chance of survival when the bird is most vulnerable to the threat of starvation, and this may also explain its white plumage. Similarly, the white color may allow juveniles to integrate with flocks of other herons with white plumage and thus benefit from more protection against predators.
Little Blue herons are carnivorous, they eat fish, frogs, lizards, turtles, snakes, and crustaceans like crabs, crayfish and shrimp, aquatic insects and spiders. It eats grasshoppers, beetles, crickets, and other grassland insects when the wet areas turn dry.
The Little Blue heron is a monogamous breeder. This means that males will mate with only one female and females will mate with only one male. They are gregarious birds and they nest in groups at the edges of other heron colonies. Typically, an unpaired male arrives first at the breeding area to establish his small territory, which will be the nesting site, around the fork of a tree. The male then performs a ‘stretch display’ to females, which involves an erect crest and neck feathers, pointing his bill upwards and a little lunge into the air. 3 to 5 eggs are laid in April and incubation is for around 22 to 24 days, done by both parents. Parents feed their young by dropping food into their nest, and later, putting it into the chicks’ mouths. At about 3 weeks chicks leave the nest, starting with short trips around the area of the nest. At 30 days old, they are able to fly out of the nesting area. They become independent at around 42 to 49 days, and are able to breed at the age of one year.
Hunted in the past for its feathers, used in hat-making, today the biggest threat to this species is the degradation and loss of freshwater wetlands. It is also threatened in parts of its range by persecution because it forages at fish-rearing facilities, as well as by contamination from heavy metals and pesticides, when it forages in cultivated fields. It may also be threatened by competition from the exotic cattle egret, this bird being more aggressive than the other herons, being thought to out-compete the Little blues for food.
According to IUCN, Little Blue heron has an extremely large range but no overall population estimate is available. According to the scientific research, the total population size of the species in the southeastern U.S. (Alabama, Louisiana, Mississippi and Texas) is above 21,266 pairs. Overall, currently Little Blue herons are classified as Least Concern (LC), however, their numbers today are decreasing.
Due to their diet, Little Blue herons may affect insect and fish populations in their range.