Great and Snowy Egrets

Snowy Egret. Photo: Jamie Hall.

Great and snowy egrets, some of the most beautiful and bizarre birds found in America, were stalked by hunters for their long, soft breeding feathers to satisfy a nineteenth century fashion trend. In the 1890’s, outraged by the resultant destruction of the egret hunts, a group of Boston society women began gathering over tea to discuss what steps should be taken to save the birds and their habitat. From these talks the modern Audubon Society was born.

At the turn of the century, Victorian urbanites, especially in New York City, desired highly decorative hats ornamented with various egret feathers, heron feathers, owl heads, whole hummingbirds, fruit, furs, and mice. Bloody hunts to obtain feathers decimated egret rookeries along the Atlantic seaboard. Women’s hats emerged as a symbol of decadence and devastation and galvanized the American public to take active steps to conserve and protect wildlife.

Audubon Societies, mostly started by women, were established in many of America’s cities. Under pressure from these newly formed environmental groups, the New York State legislature, in 1911, passed the Audubon Plumage Bill—a complete ban on the sale of native bird plumes—which lead to the end of the domestic feather trade.

Despite the passing of federal legislation to protect migratory birds, egrets continually face the threat of human encroachment into their waning habitat. In the early sixties, during a political climate favoring growth and development, a grove of redwood trees in western Marin County home to an important egret colony was slated to be logged. During the nineteenth century, as trees were cut down around the San Francisco area to build the rapidly emerging city, egrets lost more and more of their breeding sites. Remarkably, the area in Marin County near Bolinas Lagoon called Canyon Ranch had survived relatively untouched.

But by the early sixties, this area was to be logged, subdivided for development, and the lagoon where the egrets fed was to be drained to make way for a four-lane freeway. Acting quickly to intervene, the Marin Audubon Society and other concerned citizens met with property owners and legislatures to discuss alternative plans. They worked out an agreement to buy the land and establish the Audubon Canyon Ranch-Bolinas Lagoon Preserve.

Now the preserve is home to one of the West Coast’s most important egret and heron breeding sites. Egrets migrate north and south through California, foraging in irrigated fields and marshlands. Starting in February, egrets and herons start arriving at Audubon Canyon Ranch to begin a lengthy breeding season that lasts through May. They flock into the redwood trees where they breed, and feed at the nearby lagoon. The preserve offers the public and researchers many opportunities to witness and study the many intricacies of egret life.

The canyon houses two types of egrets during the breeding season: snowy egrets and great egrets. Snowy egrets have entirely white plumage, a black bill, black legs, and bright yellow feet. While similar to the snowy egret, the great egret is quite a bit bigger and has a yellow bill and black feet. The males of both species arrive at Audubon Canyon Ranch before the females do to claim nest sites and begin the building process. When the females arrive male egrets bow, stretch, and fan their decorative feathers then perform intricate courtship dances that can last many hours.

Snowy egrets perform what is called the “Stretch” display, in which the male pumps his body up and down with his bill pointed skyward. For every stage of the breeding season—courtship, mating, nest building, egg-laying, and feeding—egrets go through different, elaborate displays. Copulation occurs in the nest where the average duration of contact is only ten seconds. Females lay between three and six eggs and both parents take turns incubating them. On average, incubation lasts about 24 days and the chicks fledge two weeks after hatching. In May, the chicks begin attempting flight, which is very amusing to watch.

But some aspects of egret life are less amusing. While still in the nest, egret chicks perform one of the most ruthless acts in all of the animal kingdom: siblicide, or the murder of a sibling. The two oldest chicks will attack and kill their youngest and weakest sibling, then pitch it over the side of the nest in a brutal competition for food. The mother and father do not intervene and are in fact collaborators in this murderous evolutionary scheme to weed out the weak. Female egrets, scientists believe, purposefully allow more chicks to hatch than they plan to bring into adulthood. It is part of a strategy called “parental optimism” in which an extra chick is hatched as a kind of insurance policy in case one of the two dominant chicks should fall to misfortune. If food resources are particularly abundant one year, the parents may choose to raise the third chick.

The thousand-acre preserve at Bolinas Lagoon is open to visitors during the egret and heron breeding season from the third weekend in March through the second weekend in July. Check the website below for times and directions or call Audubon Canyon Ranch at (415) 868-9244.

 

Read more!

www.egret.org