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Snowy Egret
Egretta thula
Order
CICONIIFORMES
– Family
ARDEIDAE
Authors: Parsons, Katharine C., and Terry L. Master

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Introduction

Adult Snowy Egret, breeding plumage
Figure 1. Distribution of the Snowy Egret in N. America

One of North America’s most familiar herons, the Snowy Egret is known for its beautiful breeding plumage, conservation history, conspicuousness, spectacular mating displays, and animated foraging behavior.

This species was among the most sought-after of all herons and egrets for its delicate, recurved back plumes, used to adorn women’s hats. In 1886, plumes were valued at an astounding $32 per ounce, twice the contemporary price of gold (Allan 1974). Plundering for plumes began about 1880, peaked in 1903, and continued until 1910, when outraged citizens forced the passage of laws that reduced the slaughter. Hunting continued longer in Central and South America because of continued European demand (Hancock and Kushlan 1984). The species mounted a remarkable comeback following cessation of the feather trade, even extending its range beyond that of historical record.

The Snowy’s conspicuousness stems from both its white plumage and its active, sometimes frantic foraging behaviors used to capture small fish and crustaceans. This species uses a greater range of foraging behaviors than does any other heron. Behavioral variety does not reflect a broad choice of prey but rather adaptability to a wide range of environmental and social foraging conditions, many of which involve concentrating or increasing availability of prey. Preferred foraging habitats/conditions range from small salt-marsh pools to large freshwater marshes and from solitary to mixed-species aggregations. The Snowy Egret is often the species around which such aggregations form.

The breeding behavior of this species is typical of most herons and egrets and is often embellished with the use of graceful nuptial plumes during displays. Pairs typically nest in mixed-species colonies where the Snowy is often one of the most abundant species. Island nest sites are preferred because they are less vulnerable to predators than mainland and peninsular sites.

After staging a sustained comeback during the middle of the twentieth century, this species is proving increasingly sensitive to a variety of conservation threats, as evidenced by widespread population declines in the late twentieth century. Vulnerability results from a combination of specialized foraging requirements and loss of wetland habitats. The plight of the Snowy Egret is closely tied to the prospective status of remnant coastal wetlands in the Americas.

Of 127 million acres of wetlands existing in the United States during colonial times, 100 million have been drained as of the late 1970s (Curry-Lindahl 1978). Coastal wetlands are particularly important to Snowy Egrets in the eastern and southern U.S. (Custer and Osborn 1978a). Herons that utilize pursuit or chase behaviors, like the Snowy Egret, are more specialized and selective than searchers (Kushlan 1978a). These behaviors are energetically expensive requiring Snowy Egrets to spend proportionately more time feeding than other species (Kent 1986b). Thus, they may be particularly sensitive to environmental influences which impact prey density and availability.