Be on the Lookout for Bald Eagles
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 late September to November from their summering grounds to 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 bald eagles and their offspring usually are long gone before the heat and humidity of summer truly set in. Rarely, one may remain year-round.
The bald eagles that nest in South Texas, along the coastal plain from Nueces County to near Houston, and around the 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 or along lakeshores. Sometimes those stick nests, which may have been used for twenty or more years, become so large that they literally can 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 is an exception. Incubation takes 34 to 36 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 a carrion. One adult eagle was seen in flight carrying a struggling scaup duck in its talons. Another was observed over Dunham Bat 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; these are in 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 grand 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 bird, 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 from 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 eagles have made a remarkable recovery throughout their range.
Today, one can observed our national birds in winter in several South Texas locations. Best bet sites include a variety of fishing sites such as Coletosville 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 bald eagles can often be seen during their winter residency. Those of us living in this part of South Texas are fortunate, indeed, to be able to see one of our most magnificent wild birds close up and personal much of the winter.