Introduction

Breeding Great Egret, Moonglow Dairy, Monterey, CA, 31 March.

Great Egret in basic (nonbreeding) plumage, Arcata, CA, 4 April.

Fig. 1. Distribution of the Great Egret in North and Middle America.

Intermediate in size between the larger day herons and the smaller egrets, the elegant, stately Great Egret, in its dazzling white plumage, is widely recognized in North America and elsewhere. In the Western Hemisphere, the decimation of populations of this species and other wading birds during the early twentieth century by overhunting helped spark the formation of conservation and environmental organizations, as well as laws protecting these birds. Indeed, the Great Egret is the organizational symbol for one of the oldest such groups in the United States, the National Audubon Society.

This cosmopolitan species inhabits freshwater, estuarine, and marine wetlands, nests colonially, and feeds in aggregations as well as solitarily. The breeding behavior of the species has been extensively investigated (Wiese 1976; Mock 1978, 1980), as has its foraging ecology in the southeastern United States (Kushlan 1976, 1978a, 1978b; Bancroft et al. 1990; Bancroft et al. 1994). The nesting ecology of the Great Egret has also received significant attention (Pratt 1970, 1972; McVaugh 1972; Maxwell and Kale 1977; McCrimmon 1978; Beaver et al. 1980; Mock 1980, 1984; Pratt and Winkler 1985). Its adaptability as a generalist has doubtless contributed to its global distribution and wide-ranging recovery from previous North American population decimation. (Analyses of changes in contemporary populations of the species in the southeastern United States are found in Ogden 1978 and 1994 and McCrimmon et al. 1997 .)

Relationships among the Ardeidae (herons) have been revised or relisted several times, and both the common and scientific names have changed correspondingly. The Great Egret has been classified in the past under several genera, including its own monotypic genus, Casmerodius; with other egrets in Egretta; or allied with other large herons in Ardea. English names used in the past in North America include American Egret and Common Egret, while in the Old World it has been known as Great White Egret (or even Great White Heron). Over its broad worldwide range, 4 subspecies are recognized. This account focuses on populations in the Americas (Ardea alba egretta; see Am. Ornithol. Union 1998).