The call to the Weeks Bay Foundation was of a more ominous nature than most, with the caller suggesting there might be a dead person in the woods near her home along the Magnolia River. The evidence: hundreds of vultures roosting in the trees above her house.
The vultures had suddenly appeared in the trees earlier in the day, and more birds were wheeling around above the river, descending a few at a time into trees on each bank. By nightfall, the caller said she could see several hundred vultures from her dock.
As it turns out, there wasn’t a body washed up along shore. Instead, for reasons known only to the vultures, Bemis Bay, in the Magnolia River’s upper reaches, had become an overnight sensation in the vulture world. Like a new restaurant that has everyone talking, Bemis Bay, with numerous tall pines and banks lined with the skeletons of dead trees, was the latest “it” spot for vultures. Some residents of the nearby Fish River, which has been a popular vulture roost for decades, were reportedly pleased to hear the giant carrion eaters had found a new home.
“We get more than a few calls about new vulture roosts,” said Roger Clay with the Alabama Division of Wildlife and Freshwater Fisheries. “We’ve gotten several this year. They congregate in the wintertime.”
Clay noted that the roosts are usually mixed colonies, home to two species of vultures, the black vulture, recognizable by its black, featherless head, and the turkey vulture, which sports a red, featherless head.
“Birds of a feather flock together. If a roost is good for one vulture species, its good for both,” Clay said.
The turkey vultures, he said, are also larger, and better fliers. Most importantly, the red-headed turkey vultures can smell, a decided advantage for an animal in the business of eating dead things. The black vultures lack a sense of smell, and so spend their days following American vultures to carrion.
“To me, the interesting thing is why they’ll pick one site over another. Maybe one has better perches, but there doesn’t really seem to be any rhyme or reason,” Clay said. “But, if you’re the person who has a bunch of them roosting in your backyard, it can be disconcerting.”
It can also be smelly. Vultures are large birds, and that means a lot of guano dropping from the trees. The birds are also known for an unusual method for keeping cool, called urohidrosis, which involves peeing on their own legs. Such behavior probably lends to their unsavory reputation, though once you are known for eating dead things, it is hard to do much more damage to your good name.
That behavior, the consumption of carrion, appears to play a central role in the roosting behavior of vultures. An article on the Cornell Lab of Ornithology’s web site by Jack Connor details a long running experiment by ornithologist Patricia Parker Rabenold.
In the 1980s, Rabenold captured and tagged more than 300 vultures and studied their behavior for several years. The vultures she captured were part of a larger group of 1,200 that shared a total of seven roosting spots, meaning roughly 200 birds per roost. With numbers like that, it is easy to see how the Magnolia River caller reported seeing several hundred roosting around her yard.
Rabenold’s findings suggest that young birds follow the adults from the roosting site in the morning, learning on the wing how to find carrion. At the end of the day, the young birds follow the adults back to the roost. Her research also revealed that young birds often roost with their parents, and follow them on their hunting trips.
One of the key tricks for the black vultures is simply to follow the larger turkey vultures, which use their sense of smell. It is the turkey vultures most often seen circling high over head in the middle of the day. They are riding warm air currents, known as thermals, waiting for the telltale stink of death to float up to them.
Clay said that calls about vultures usually increase in the winter, due to an influx of migrating vultures fleeing cold weather. Think of them as giant, black, carrion eating snowbirds.
“They’re migratory. Obviously, we have resident vultures, but we do get an influx of birds from up north,” Clay said. “Once it warms up, they’ll spread out, and we won’t be getting the calls until next winter.”
Ben Raines is the executive director of the Weeks Bay Foundation, a non-profit land trust dedicated to protecting and preserving coastal Alabama. For more information about the Foundation, or to join, visit weeksbay.org. Follow Ben Raines on Facebook or Twitter at BenHRaines.