Vultures Take Over Suburbia
They vomit all over the place, urinate on themselves to cool off, and feed on the dead. Now they're disgusting and even frightening suburban homeowners. But vultures are amazing creatures that are a key part of the food chain, and they reveal a lot about wildlife's ability to adapt to us.
Soaring on rising currents of heated air, carving sooty gyres hundreds of feet overhead, vultures bring a graceful smudge of life to the birdless skies of midday. A bird common from southern Argentina and Chile north through Central America and the Gulf Coast states, black vultures in the United States were once considered a denizen mostly of the Southeast. But they have marched--or rather soared--north up the East Coast for the better part of a century. (Turkey vultures are much more widely distributed, breeding as far north as southern Canada.) As late as the 1930s black vultures weren't known to breed much farther north than central Virginia. They were found breeding in southern Maryland by the late 1940s, in Pennsylvania in 1952, in New Jersey in 1981, and in New York in 1997.
At the same time, various population surveys have recorded a generally impressive climb in numbers. Between 1990 and 2005, Christmas Bird Count data showed an overall tripling in black vulture sightings. During the same time period, Breeding Bird Survey data from the U.S. Fish and Wildlife Service indicated more than a three percent annual increase--a rate that would double the current U.S. population in less than 15 years. Blixt estimates that the bounce is even higher, averaging about 10 percent. Some states, including Pennsylvania and New Jersey, have even seen the populations jump by a rate as much as three times the national average. "We're starting to realize the link between black vulture population increases and range expansions and human population growth," explains Bryan Watts, director of the Center for Conservation Biology at the College of William & Mary, in Williamsburg, Virginia.
Black vultures are among the most resilient members of the vulture family, even though they are slightly smaller than their cousins, the turkey vultures. Black vultures can better tolerate human presence. While most turkey vultures migrate, black vultures are largely residents. The olfactory bulbs of black vultures are much less developed than those of turkey vultures, so they rely more on sight to find a rotting good meal. They tend to fly higher than the turkeys, spot other vultures circling over carrion, then soar in for the steal. And their smaller size is no impediment to their packlike scavenging techniques; black vultures will gather in large groups and drive turkey vultures off a prize find of carrion.
"They are extremely resourceful," says Bildstein. While conducting vulture surveys in Central America, he has watched black vultures drag coconuts onto highways, wait for passing cars to smash the nuts, then eat from the broken shards.
Many bird lovers find this species' quirky habits and odd looks fascinating. "Watch how black vultures fly," says Elaine Leslie, a National Park Service biologist who has studied New World vultures in Florida. "Watch how they socialize. These are some of the coolest birds out there."
Old World cultures viewed vultures far more affectionately than New World suburbanites. Early Egyptians held that vultures would reveal the site of an upcoming battle by appearing there seven days prior to bloodshed. And their scavenging habits were so highly valued, especially in ancient Egypt's intense heat, that one pharaoh decreed the death penalty for killing a vulture--making it, perhaps, the first protected species.
Even their least savory traits are bewitching. Black vultures vomit defensively--"with wonderful quickness and power," marveled James John Audubon. Their distinctive urinary habits are astonishingly clever; the practice of urohydrosis--excreting down their legs--is a useful means of chilling the blood in their lower extremities and redistributing it through the body to stay cool.
These vultures have elongated, hooked bills designed to probe deep inside decaying bodies of whatever misfortunate beings they come across--be it mammal, bird, or fish. Featherless heads are easier to keep clean, a great benefit for a bird that frequently buries its noggin in rotting viscera.
Then again, from time immemorial vultures have had their share of detractors. Early taboos against touching dead bodies put vultures in a singular category of grotesquery, and Old Testament texts considered them "an abomination among the birds." Charles Darwin, of all people, cheerlessly ranted that vultures were "disgusting" and "wallow in putridity." He might have felt at home in Leesburg.
"They are ugly as *!%#," fumes Alan Ogden, as he plants yellow pansies in window boxes four houses down from the harassment in Leesburg, shaking his head and straining to speak above the pyrotechnic shells screaming in the background. "They smell like ammonia and sewage. I walk around the corner and 50 of them are sitting on gravestones, hissing. It's like living in a horror movie. If it were up to me, I'd kill every one of them."
Fortunately, few people subscribe to that view. But it is also true that roosting vultures congregate near homes and businesses, where they fly from trees to rooftops in the early morning to warm themselves in the sun. Once roosts are established, says Martin Lowney, who served as state APHIS director in Virginia until his recent relocation to New York, the birds "strip shingles from roofs, vomit all over the deck and grill, and tear kids' toys apart."