Snowy egret (Egretta thula)
|Also known as:||Brewster’s egret, little white egret, snowy heron|
|Size||Length: 47.5 - 68 cm (2)|
Wingspan: c. 96 cm (2)
|Weight||c. 370 g (2)|
The snowy egret is classified as Least Concern (LC) on the IUCN Red List (1).
A familiar heron of the Americas, the snowy egret (Egretta thula) is well known for its spectacular mating displays, frantic foraging behaviours and beautiful all-white plumage (3). During the breeding season, this medium-sized heron develops long, thin, wispy plumes along the neck, breast and back and a short, shaggy crest on the back of the head (3) (4). At the height of the breeding season, the conspicuous yellow feet and the bright yellow bare skin between the eyes and the bill become richer in colour, often with a reddish or orange tinge (2) (3).
The snowy egret has a thin, black bill and slender, black legs, which have a yellow stripe on the back (3) (4). 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 (3).
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 (5).
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 (6).
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 (6).
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 (6).
Foraging in or near to shallow water for a mixture of prey that includes fish, crustaceans, insects, frogs, lizards, snakes, rodents, snails, and worms (7), 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 (4) (8).
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 (5). 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 (5).
The snowy egret is an extremely gregarious species, nesting in dense colonies of mixed heron species (4), 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 (5). The female builds the nest with sticks collected by the male, and two to six eggs are then laid (8). The eggs are incubated for 20 to 24 days and the chicks are fed on regurgitated food by both adults (4) (5). The chicks fledge after around 30 days (2), and usually breed for the first time in their second year (4).
The snowy egret was once highly sought after for its delicate, curved back plumes, which were used in the hat-making trade. Plundering of this species for its plumes began around 1880 and populations declined as a result of this exploitation (3) (8). Public outrage over the neglect of snowy egret populations led to this species obtaining protection in the US in 1910, and its populations subsequently mounted a remarkable recovery (3) (5). Today the snowy egret population is continuing to increase in both number and range, and it probably numbers higher than at any other time in its recent history (2) (4) (9).
However, despite previous increases, the snowy egret is susceptible to a number of threats, and it is still rare and decreasing in parts of its range (3). In Florida, where it is listed as a Species of Special Concern, wetland destruction and degradation has eliminated key snowy egret foraging habitat (4), and by 1989 this species was found in only 22 percent of the colonies where it formally occurred (6). Also, in the central US, reproductive success has declined due to accumulation of DDT in the environment (3) (8).
With the snowy egret population declining in parts of the US, efforts to conserve this species have been renewed. In New Jersey for example, a former colony site is being restored and model egrets are being used to encourage breeding snowy egrets to the site. The Florida Fish and Wildlife Conservation Commission and the Department of Environmental Protection have also developed a minimum distance of around 100 metres for approaching wading bird colonies so as to limit human disturbance (6).
Hunting of the snowy egret is also prohibited by the Migratory Bird Treaty Act, which has been ratified by the governments of Mexico, Canada and the United States and prevents the killing or harming of the snowy egret, including its nests and eggs (3). Additional recommended conservation measures for the snowy egret include managing wetlands to prevent rapid changes in water depth, restoring and maintaining water flow patterns in degraded wetlands, and protecting breeding and foraging habitats through the establishment of reserves (6).
For more information on the snowy egret and other bird species, see:
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- Crustaceans: diverse group of animals with jointed limbs and a hard chitinous exoskeleton characterised by the possession of two pairs of antennae, one pair of mandibles (mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps and barnacles.
- DDT: an abbreviation for dichlorodiphenyltrichloroethane, a pesticide.
- Incubate: to keep eggs warm so that development is possible.
- Territory: an area occupied and defended by an animal, a pair of animals or a colony.
IUCN Red List (December, 2010)
- del Hoyo, J., Elliott, A. and Sargatal, J. (1992) Handbook of the Birds of the World. Volume 1: Ostrich to Ducks. Lynx Edicions, Barcelona.
Parsons, K.C. and Master, T.L. (2000) Snowy egret (Egretta thula). In: Poole, A. (Ed.) The Birds of North America Online. Cornell Lab of Ornithology, Ithaca. Available at:
Smithsonian Marine Station at Fort Pierce – Snowy egret (January, 2011)
- Kushlan, J.A. and Hancock, J.A. (2005) Bird Families of the World: Herons. Oxford University Press, Oxford.
Field Guide to the Rare Plants and Animals of Florida – Snowy egret (January, 2011)
South Dakota Birds and Birding - Snowy egret (January, 2011)
- Nellis, D.W. (2001) Common Coastal Birds of Florida and the Caribbean. Pineapple Press, Florida.
BirdLife International (January, 2011)