| Great
Egret |
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Great
Egret (Casmerodius albus)
By Barbara A. Garrison, Nongame Biologist |
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 Scientific
Name:
Casmerodius albus. The genus stems from the Greek Kosmos, meaning ornament,
or kosmetos, meaning adorned, in reference to the beautiful plumage and
nuptial plumes (aigrettes). The specific epithet is derived from the Latin
alb, meaning white.
Description:
A tall, slim-necked water bird with white plumage, heavy yellow bill, long
black legs, and black feet. Males and females similar; males slightly larger.
About 37 to 41 inches long, with a 55-inch wingspread. Weight 32 to 40
ounces. In breeding season, long nuptial plumes extend from back to beyond
tail. Immatures and nonbreeding adults have dull bill and legs, and lack
plumes. In flight, long neck tucked back on shoulders in S-shape, and legs
extended straight back. |
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Habitat:
Inhabits rivers, streams, ponds, lakes, marshes, and mud flats that are
often dominated by cattails, reeds, and other emergent plants. Forages
in open wetland habitats, especially along vegetated edges of large
waters. Breeding may be limited by availability of tall riparian trees
for nesting, though citrus groves have been used in the Yuma area. |
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Distribution:
Breeds in southern North America to South America. Winters in southern
and western United States, and South and Central America. Scattered
breeding flocks occur along the lower Colorado River. Found in central
Arizona as a post-breeding wanderer during most of the summer. During
winter, scattered flocks and individuals often seen along larger rivers
and lakes in southern and western Arizona. |
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Biology:
Great egrets consume fish, insects, and amphibians with equal abandon.
They rake the watercourse bottom with their feet to flush prey into
sight, then strike with their long, spear-like bills. Egrets forage
during the day, and in late evening congregate at roosts, where they
remain until daybreak.
During nesting season (spring), pairs of egrets perform a beautiful, graceful
courtship display that includes greeting one another with erect plumes
and wings raised straight out. In flight, they circle one another and emit
calls while their necks are stretched skyward. Great egrets nest in waterside
thickets and trees, often in mature cottonwoods, willows, and salt cedars
along shorelines. They nest singly or in groups, often with other egrets
or herons. Their stick nests are loosely constructed and generally unlined.
The three or four light blue or light bluish-green eggs are incubated for
23 days. Young leave the nest about three weeks after hatching. Raccoons,
ravens, and vultures often prey on unguarded eggs and young. |
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Status:
The great egret was included on the Department's list of Threatened Native
Wildlife in Arizona (1988) as endangered, but no longer appears to
be at risk here. The species is not listed or proposed for listing
by the U.S. Fish and Wildlife Service as endangered or threatened. |
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Management
Needs:
Great egret numbers plummeted at the turn of the last century, when the
millinery feather trade was thriving and plumes were valued at $32 per
ounce. Market and feather hunting devastated egret and heron populations,
leading to the creation of the National Audubon Society and federal laws
to protect migratory birds. Those days of unregulated harvest are long
since over, although vandalistic shooting still takes a toll (especially
of nesting birds). Today, the principal threats are loss of riparian trees,
drainage of marshlands, and environmental contaminants. Recreational use
of backwaters and coves by boaters and jet skiers may also disturb breeding
egrets. Protection of important nesting areas and wetlands will provide
adequate safeguards against population declines. |
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