The elegant Great Egret is a dazzling sight in many a North American wetland. Slightly smaller and more svelte than a Great Blue Heron, these are still large birds with impressive wingspans. They hunt in classic heron fashion, standing immobile or wading through wetlands to capture fish with a deadly jab of their yellow bill. Great Egrets were hunted nearly to extinction for their plumes in the late nineteenth century, sparking conservation movements and some of the first laws to protect birds.
Great Egrets are tall, long-legged wading birds with long, S-curved necks and long, dagger-like bills. In flight, the long neck is tucked in and the legs extend far beyond the tip of the short tail. Standing up to 1 m (3.3 ft) tall, this species can measure 80 to 104 cm (31 to 41 in) in length and have a wingspan of 131 to 170 cm (52 to 67 in). Body mass can range from 700 to 1,500 g (1.5 to 3.3 lb), with an average of around 1,000 g (2.2 lb).
All feathers on Great Egrets are white. Their bills are yellowish-orange, and the legs black. The pristinely white Great Egret gets even more dressed up for the breeding season. A patch of skin on its face turns neon green, and long plumes grow from its back. Called aigrettes, those plumes were the bane of egrets in the late nineteenth century, when such adornments were prized for ladies’ hats.
There is a white form of the Great Blue Heron that is found in the Carribean that is often confused with the Great Egret. However, the white form of the Blue Heron has yellow legs and a straw coloured bill.
You’ll find Great Egrets in both freshwater and saltwater habitats. They are colonial nesters, typically placing stick nests high in trees, often on islands that are isolated from mammalian predators such as raccoons. Great Egrets wade in shallow water (both fresh and salt) to hunt fish, frogs, and other small aquatic animals. They typically stand still and watch for unsuspecting prey to pass by. Then, with startling speed, the egrets strike with a jab of their long neck and bill.
Great Egrets form monogamous pairs each breeding season, though it’s not known whether the pair bond lasts through multiple years. Early in the breeding season adults grow long plumes on their backs, which they raise in courtship displays. Males perform most of the displays, which can involve preening the wings, ducking the head, holding and shaking twigs in the bill, and stretching the neck. Males choose the display areas, where nests are later constructed. The nest itself is up to 100 feet off the ground, often over water, usually in or near the top of a shrub or tree such as a redwood, tamarisk, live oak, eastern redcedar, yaupon holly, wax myrtle, mangrove, Australian pine, buttonwood, Brazilian pepper, black willow, or privet. Great Egrets occasionally nest on the ground or on artificial platforms. The male builds a nest platform from long sticks and twigs before pairing up with a female, and then both members of the pair may collaborate to complete the nest, though the male sometimes finishes it himself.
The nest is up to 3 feet across and 1 foot deep. It is lined with pliable plant material that dries to form a cup structure. They don’t typically reuse nests from year to year. The female great egret lays three to five pale green-blue eggs. The eggs take about three to four weeks to incubate. Both parents incubate the eggs and feed the chicks. The chicks fledge in about six weeks. Not all young that hatch survive the nestling period. Aggression among nestlings is common and large chicks frequently kill their smaller siblings. This behavior, known as siblicide, is not uncommon among birds such as hawks, owls, and herons, and is often a result of poor breeding conditions in a given year.
More than 95 percent of the Great Egrets in North America were killed for their plumes in the late nineteenth and early twentieth centuries. Plume-hunting was banned, for the most part, around 1910, and Great Egret populations quickly began to recover. Since the 1930s, the egrets have had to contend with major habitat loss and degradation, as well as threats like contaminated runoff from farm fields or sewage treatment. However, their populations appear stable. Compared to other egrets and herons, Great Egrets seem to be unfazed by habitat loss on a localized scale, even in extremely altered landscapes like the Everglades. Since Great Egrets are large, very mobile birds with flexible habitat preferences, environmental changes may be affecting them at a larger scale that has yet to be studied.
References: Wikipedia, Cornell Lab of Ornithology, Nature Works (http://www.nhptv.org)