The snowy egret has a thin, black bill and slender, black legs, which have a yellow stripe on the back. The breeding male and female look alike, but the juvenile and non-breeding adult have a pale greyish base to the lower mandible and duller, greenish-yellow feet, with this colour extending up the lower leg to the knee joint. Whilst foraging, the snowy egret walks upright with the neck slightly arched, and it flies strongly with deep wing beats, the yellow feet visibly trailing behind the body. It is an extremely vocal heron, particularly during aggressive encounters, when a characteristic “rah” call is emitted. This becomes harsher with the intensity of the encounter.
The snowy egret is often confused with the juvenile little blue heron (Egretta caerulea), but may be distinguished by the pure white tips on the wing feathers, the solid black bill and the bright yellow feet, which give the impression that the bird is wearing gloves.
Foraging in or near to shallow water for a mixture of prey that includes fish, crustaceans, insects, frogs, lizards, snakes, rodents, snails, and worms, the snowy egret exhibits a great variety of foraging techniques. It uses a series of rapid, frantic movements to startle or surprise its prey, including flicking the wings, walking quickly, hovering and dipping the bill while in flight, and using its feet to stir, rake and probe the substrate. The typical heron strategy of foraging is also used, in which the egret stands, waiting patiently until prey comes so close that it can strike out with the long bill and grab its target.
The timing of breeding varies greatly across the snowy egret’s very large range, but nesting is typically associated with the wet season in the tropics and occurs between March and May in the US. The male snowy egrets arrive at the nesting grounds first, to establish a display and nesting territory. The male’s displays are both extravagant and unusual. It circles in the air before descending to a perch, where it points the bill upwards and then pumps the head up and down, all the while giving a “Wah” call. As courtship continues, breeding birds pair up, after which the male bird performs a number of additional, unusual displays.
The snowy egret is an extremely gregarious species, nesting in dense colonies of mixed heron species, often building its nest as close as one metre to that of another heron. The nest is a flat, shallow platform of sticks placed three to ten metres above the ground in a woody shrub or mangrove tree. The female builds the nest with sticks collected by the male, and two to six eggs are then laid. The eggs are incubated for 20 to 24 days and the chicks are fed on regurgitated food by both adults. The chicks fledge after around 30 days, and usually breed for the first time in their second year.
The snowy egret has a very wide range, extending from northern California, southern Montana, central Kansas, and Tennessee, east to the Atlantic coast of North America, and south to southern Chile and central Argentina. In North America it is a migratory species, wintering along the coastline from northern California to Arizona, along the northern Gulf coast, and along the Atlantic coast to South Carolina.
Occupying a great variety of habitats, the snowy egret feeds in many types of permanently and seasonally flooded wetlands, streams, lakes, swamps and man-made habitats, as well as coastal marshes, shallow bays and mangroves. It nests in both inland and in coastal wetlands, with nests typically placed in a woody shrub over shallow water.