Blue Ridge Naturalist: A Black Vulture a Day Keeps Disease Away
© Marlene A. Condon
Many farmers have decided that the Black Vulture is a predator that takes newborn calves and lambs. And when a problem arises nowadays that involves wildlife, the attitude of most people is to simply kill the offending animals.
However, that knee-jerk reaction can bring about much more serious problems in the long run because all organisms provide services that are vital to our own well being.
For example, the value of vultures to our waterways is largely overlooked. They help to limit health hazards throughout the 64,000 square miles that comprise the Chesapeake Bay watershed.
Some 150 major rivers and streams, plus innumerable smaller tributaries, deliver water to the bay, and I have observed vultures performing their important purification services along my own local river.
One day as I was exercising, I noticed vultures perched in the trees up ahead of me. They were overlooking the river that the road parallels, and I knew their presence was a sure sign that there must be a dead animal somewhere in their vicinity.
When I got closer, I could see several of these big birds standing on a dead deer that was lying in the river. It’s likely the deer was hit by a car but not immediately killed, and then managed to reach the river just a short distance away where it then died.
It’s also possible the deer was ill before it perished in the waterway. Although most wildlife is healthy, sometimes animals get sick, just as we do, and a severely ill animal often makes its way to water. It knows it will continue to require this vital substance to remain alive, but unfortunately, it may then succumb to its illness in or near the water it had sought.
When carcasses end up in or along waterways, they can contaminate them if not removed in short order. Indeed, when vulture populations plummeted in South Asia, it led to a proliferation of rats and a rise in infectious diseases as a result of carcasses left to rot on the ground. (http://www.birdlife.org/datazone/sowb/casestudy/156[birdlife.org])
When an animal dies, it begins to decompose almost immediately. Particular species of bacteria work to recycle the dead creature and in the process produce bio-toxins. These natural poisons can sicken or kill people and most animals other than vultures.
Therefore a vulture is the ultimate sanitation worker to provide carcass removal services because it’s able to metabolize the noxious substances found in decaying flesh. It’s protected by highly acidic stomach liquids.
Wildlife conflicts between vultures and people must be resolved by the Wildlife Services division of the U.S. Department of Agriculture because these birds are protected by the Migratory Bird Treaty Act. But farmers haven’t been satisfied with the federal handling of their complaints, so they talked a state senator into introducing a bill this legislative session to make it easier for them to kill Black Vultures.
Because vultures reproduce very slowly and would be unable to quickly rebound in numbers, killing too many of them could impact the health of waterways and subject the bay to yet another stressor. Additionally, disease would be allowed to linger in our environment.
A female Black Vulture nests only one time each year, laying one to three eggs that take over a month to hatch. The young remain in the nest for two to three months, which comprises most of the breeding season.
Senate Bill 37 (SB37) to allow farmers to kill Black Vultures is quite likely to become law, but it shouldn’t. The crime the Black Vulture is accused of—killing lambs and calves—doesn’t make sense. This bird is not designed for hunting.
American architect Louis Sullivan wrote, “Form ever follows function, and this is the law [of nature].” With flat, weak feet and blunt talons that are not capable of grasping (form), the Black Vulture is clearly designed for scavenging (function).
So how and why is this species killing newborn animals instead of feeding only upon dead ones? When animals start behaving unnaturally, there’s a logical reason for it. The answer to the vultures’ strange behavior in Virginia is obvious if you’ve been paying attention to our environment over the course of the past 20-30 years.
Many farmers have done away with hedgerows, the mix of shrubby and herbaceous growth that had served as protective windbreaks as well as habitat for wildlife, such as Northern Bobwhite Quail that have disappeared in Virginia along with the hedgerows.
Today’s farm is typically wall-to-wall fescue (grass) with a few large trees. This unnaturally barren land has not only destroyed wildlife habitat, but has also done away with a “birthing room” for cows and ewes where they can safely give birth.
Pregnant females actively seek a spot away from the rest of the herd or flock where they can hide from predators while bringing new life into the world. But a field devoid of cover forces them to give birth out in the open, where they can be easily seen by predators and vultures that, like any hungry animal, will take advantage of a situation that presents the opportunity for an easy meal.
In this case, the vultures have learned that the afterbirth (the placenta, which is the membrane that transfers nutrients from the adult female to her young in the womb) will be expelled shortly after the birth takes place and they wait for it. As for the claim that Black Vultures deliberately kill newborn lambs and calves, I believe people are misinterpreting what’s actually happening.
Newborn lambs and calves are covered in mucus, a mixture of water, sugars, proteins, and other substances that are just as appealing to vultures as the afterbirth. These scavengers could be simply trying to feed upon this mucus, rather than intentionally trying to kill the newborn animal.
Additionally, Black Vultures are often getting blamed for killing newborns when, in reality, the young were born sickly and abandoned by the mother or succumbed to the cold. The natural time of year for most mammals to give birth is spring, but farmers often manipulate births to occur in late fall or winter, which is unnatural and thus inappropriate.
The difficulty that farmers are experiencing with the Black Vulture is a relatively recent development that mirrors the growing disconnect between humans, their environment, and their livestock. When people refuse to live within the context of the natural world, it invariably creates problems.
Virginians should insist that Governor McAuliffe resist passing SB37, a law that enables poor farming practices that are the root cause of the problem.
Farmers have a duty to take reasonable steps to ensure the welfare of their animals, and they should use their intelligence to accept, and work within, the constraints set by the natural world, rather than trying to ignore real-life limitations on their actions.