Eagles
soar in troubled sky
By Callan Bentley
Flat Hat Variety Editor
The summer after my freshman year, I was awarded the opportunity to undertake some real biology field research. I was studying the feeding behavior of birds called cattle egrets (Bubulcus ibis) at a fish hatchery in Charles City County.
When I began the study, I thought that field research was going to be my life's work, but now I know better. A great many problems pop up in the course of a day's field work. But I could have expected all that. What I didn't expect was the one day when a bald eagle swooped down, snagged one of my cattle egrets, and flew off with the smaller bird hanging limply from its talons.
My summer roommate was doing ornithology research too, and since his topic was eagle foraging behavior, he was ecstatic to hear of this victory of 'his' bird over 'my' bird. I was less than amused by the incident, but I could see a bright side to it too. The bald eagle, once an endangered bird, is coming back from the abyss of extinction and apparently holding its own in the modern world.
The bald eagle is one of the largest birds of prey on our continent. Its wings may span a distance of up to eight feet. It is not actually bald, but as an adult has a head covered in white feathers, which stand in stark contrast to its dark brown body. The tail is also white in adult birds, but it takes four or five years for a bald eagle to reach adulthood. Until then, they are brown with evenly-distributed whitish splotchy marks all over them.
Before this century, bald eagles (Haliaaetus lecuocephalus) were common along the Chesapeake Bay and its tributary rivers in Virginia. Two things caused their downfall in the 1950s and 1960s: habitat loss and adverse effects from pesticides such as DDT, which made eagle eggs much more fragile and thin (so fewer of them hatched).
But wrongs have been righted, and our national mascot is experiencing a resurgence. According to a report prepared by the College's Center for Conservation Biology, "In Virginia, the breeding population has steadily increased from an estimated 32 pairs in the late 1960s to 151 pairs in 1993."
Despite these encouraging statistics, habitat loss is continuing to threaten the eagle's lifestyle. Without enough proper places to live, eagles will die, and the population will never be as robust as it could have otherwise been.
Bald eagles are in peril due to habitat loss mainly because of their nesting preferences. They nest near large water bodies, usually away from human habitations. You can find them along the shores of both the James and York Rivers.
They build incredibly huge nests, starting with a pile of sticks three or four feet in diameter and adding to it over the years until it may become as large as ten feet in diameter and 15 feet in depth. The same pair of eagles will use a nest for a long time, and some have been known to rear young in the same tree for 25 consecutive years.
These large nests weigh a lot, so large old trees and needed to give them proper structural support. Also large trees tend to stand above the surrounding trees, which offers two advantages to the eagles: easy flight in or out of the nest, and an unobstructed view of the surrounding area. Loblolly pines (such as those growing behind Millington Hall) are often used for nesting purposes.
Besides taking the occasional cattle egret, bald eagles will eat many other things. They will prey upon fish, birds, and small mammals, but are also scavengers on par with the turkey vulture. This is why DDT proved so traumatic to their population: fish ingested pesticide in the water, and it killed them. Suddenly presented with a smorgasbord of dead fish, the eagles snacked away happily, unaware that they were ingesting poison, too.
Another reason to fight for habitat preservation is that eagles forage in a certain way. They need large dead trees situated at proper points along the shoreline, so they can sit and scan without too much effort. When it sports a food item, the eagle will get it, often bringing it back to the same perch to consume.
Eagles do not have an inspiring call. While you will often see their pictures on television with a beautiful birdlike scream on the audio track, this is a misrepresentation. The call you hear is that of the red-tailed hawk, a beautiful wild high-pitched keen. But the bald eagle makes a harsh creaking cackling noise, not especially notable.
Bald eagles will occasionally
visit the campus. I have seen them circling over the College Woods and over
the football stadium. Keep alert and aware and you, too, may witness the comeback
of these predaceous birds.