The Nature Writers of Texas

The best nature writing from the newspaper, magazine, blog and book authors of the Lone Star State . . .

Sunday, September 30, 2007

Bald Eagle Time Again in South Texas
by Ro Wauer

It is again time for the annual arrival of bald eagles into South Texas. Southern bald eagles normally return to their ancestral nesting sites in September to November from their summering grounds in the north. They will remain through the winter months, nest in midwinter, and leave in March or April. Young birds may linger into early May, but all of the adult birds and their offspring usually are long gone before the heat and humidity of summer truly sets in. Only rarely does one remain year-round.

The bald eagles that nest in South Texas, along the coastal plain from Nueces County to Houston, and around lakes in northeastern Texas, are members of the southern bald eagle race, rather than the northern race of bald eagles that nest north of the state and as far away as Alaska. All bald eagles are long-lived and mate for life, although if one of the pair dies, the remaining bird will usually take a second mate. Adult nesters construct huge stick nests in trees usually located along waterways. Sometimes those stick nests, which may have been used for twenty or more years, become so large that they literally break down the tree branches. One nest was measured at 10 feet across and 20 feet deep.

Females normally lay two or three large, bluish white eggs, but more than two hatchlings are an exception. Incubation takes thirty-four to thirty-six days, and the nestlings are fed by both parents for about three months before fledging. So by the time the southern youngsters are flying, it is time for them to go north. More often than not, the adults will leave ahead of the uncertain youngsters.

Although bald eagles take advantage of available carrion, their diet is rather broad. Wayne and Martha McAlister write in their book, A Naturalist’s Guide: Aransas, that “food items found in the nests on the Aransas generally confirm the eagle’s diet of fish and waterfowl: flounder, mullet, red drum, a white pelican, many American coots, pintails, scaups, and numerous grebes; swamp rabbits and cottontails, and one armadillo that may have been picked up as carrion. One adult eagle was seen in flight carrying a struggling scaup duck in its talons. Another was observed over Dunham Bay dive-bombing an osprey in an apparent attempt to make it drop its fish.”

Adult bald eagles are truly magnificent birds, with a snow-white head and tail and a huge yellow bill that are stark contrasts to its chocolate brown body. Its general appearance as a fierce predator also is in contrast to its true character, that of a timid carrion feeder. But anyone who has watched one of these magnificent creatures for any length of time cannot help but be impressed. In fact, Congress declared the “American eagle,” instead of the wild turkey that Benjamin Franklin preferred, as our “national bird” on June 20, 1782.

Yet in spite of the bald eagle being established as our national emblem, North American populations declined precipitously during the 1950s and 1960s, primarily as a result of egg-shell thinning caused by pesticides and heavy metals that the birds absorbed through contaminated fish and other foods. The birds were listed as endangered by the United States and Canada in 1963, and DDT, one of the most long-lived and widespread pesticides, was banned for use in the United States and Canada in 1972. Since then, bald eagle populations have made a remarkable recovery throughout their range. And last year it was delisted.

Today, one can observed one of our national birds in winter in several South Texas locations. Best bet sites include a variety of fishing sites such as Coletoville Reservoir, Lake Texana, and various points along the Guadalupe and San Antonio rivers. And Dupont Victoria has constructed an observation platform along the north entrance road to the plant where as active bald eagle nest can be seen. What’s more, the public is welcome!


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