Black vultures (Coragyps atratus) are scavenging birds found in the southeastern United States that play an important role in the ecosystem by consuming carrion. However, they have frequently come into conflict with humans, often feeding on livestock and damaging property. As a result, black vultures were historically subject to eradication programs and bounty hunting, causing their populations to decline dramatically by the 1960s. To prevent further declines, black vultures were granted legal protection under the Migratory Bird Treaty Act in 1972, making it illegal to harm or kill them without a permit.
Black Vulture Biology and Behavior
Black vultures are large, blackish birds that reach lengths of 24-28 inches and weigh 4-5 pounds as adults. They have bald, red or black heads and necks without feathers. Their wingspans are around 5 feet wide, allowing them to soar for hours without flapping. Black vultures have an excellent sense of smell, better than any other New World vulture, allowing them to find carcasses by scent. They have weak feet and legs, however, so they cannot tear into thick hides themselves. Instead, they rely on larger turkey vultures and other scavengers to open carcasses for them.
Black vultures are gregarious, roosting in groups of up to several hundred birds. Their social nature helps them to find food sources. Groups will fly in search of carcasses, with the first vulture to spot food signaling the others. At carcasses, black vultures gorge themselves and often overheat. To cool down, they urinate on their legs or find shade.
Diet
As scavengers, black vultures feed almost exclusively on carrion, or dead and decaying animals. They rarely prey on live animals themselves. Carrion forms include large mammals like livestock, deer, rabbits and opossums, but black vultures also consume smaller animals like fish and even reptiles and amphibians. They forage mainly by sight and are attracted to movement, circling above roads and fields for possible carcasses. Their highly acidic stomachs allow them to digest carrion infected with botulism, anthrax and other deadly bacteria that could sicken other animals. Their stomach acid kills these microbes, rendering the carrion safe for the vultures.
Range and Habitat
Black vultures are found year-round across the southeastern United States, from south New Jersey and Missouri to Texas and south Florida. Their breeding range extends across the southern U.S. from North Carolina to California. Though they migrate north in summer, most black vultures do not venture more than 100 miles north of their nesting sites.
These vultures occupy varied habitats within their range, including forests, pastures, wetlands, suburbs and garbage dumps. They roost in dead trees, on building ledges and atop billboards and towers. Since they rely on sight to forage, black vultures favor open habitats over dense forest. They thrive in rural areas with mixed forest and agricultural fields that provide woods for roosting and open land for spotting carrion.
Population Status
Early in the 20th century, black vulture populations were threatened by eradication programs, shooting and egg destruction. The birds were considered pests and dangers to livestock because of their predation on young farm animals. With no legal protection, black vulture numbers declined to just 300,000 birds by the 1960s, down from an estimated 2 million historically.
To prevent further losses, black vultures were granted protection under the Migratory Bird Treaty Act in 1972, making it illegal to harm or kill them without a permit. Their numbers rebounded to around 2 million birds today as a result of this protection. However, black vultures are still occasionally subject to illegal shooting and poisoning when they congregate near farms and ranches. Their populations remain vulnerable particularly in the northern parts of their range.
Conflicts With Humans
One of the main reasons black vultures were historically persecuted was their propensity to prey on livestock, especially newborn calves, lambs and pigs. The vultures will attack weak or vulnerable animals by pecking out their eyes and eating them alive. This understandably angered farmers and led to retaliatory killing of the birds. Vultures also damaged homes and other property with their droppings when roosting on buildings.
These conflicts continue today in farming areas. Black vultures still occasionally kill livestock, though more often they feed on animals killed by other causes. Their droppings can damage roofs and vehicles near urban roosts. And large flocks may prevent aerial crop dusting when they congregate in fields. These issues lead some people to illegally shoot or poison vultures, hindering conservation efforts.
Importance of Vultures to Ecosystems
Despite issues with livestock, vultures provide valuable ecological services that make their legal protection necessary. As scavengers, they help clean up carcasses and prevent the spread of diseases like anthrax and rabies that could be transmitted by rotting carcasses. Vultures have very acidic stomachs that kill deadly bacteria in decaying meat. They present almost no risk of spreading livestock diseases themselves.
Turkey vultures are unable to tear through the thick hides and fur of carcasses. So black vultures help provide access to meat for both species. Without vultures, other scavengers like feral dogs would likely increase and become the dominant scavengers, potentially spreading more diseases. Vultures also help prevent greenhouse gas emissions from carcasses. Overall, they are very important for maintaining healthy, sustainable ecosystems.
Non-Lethal Management Solutions
Given the ecological benefits of vultures, completely eliminating them is not a good management approach. Instead, non-lethal methods should be employed to prevent conflicts with livestock where they occur. Simple harassment, using loud noises and harassment, can deter vultures from an area. Devices like effigies of dead vultures hung upside-down also deter them from roosting in unwanted sites.
Farmers can protect vulnerable livestock by penning them in shelters and sheds at birth before letting them out into fields. Extra monitoring when the young animals are let outside can also prevent vulture attacks. Carcass disposal sites should be set far from livestock fields and pens so as not to attract vultures. Following these practices can allow farmers and vultures to coexist without illegal killing of protected birds.
Permit Requirements for Control
In some unavoidable cases, more forceful management may be needed if vultures are causing excessive damage. However, a permit is required to take any action against black vultures other than passive harassment. To legally kill a destructive vulture, farmers must contact the U.S. Fish and Wildlife Service and apply for a migratory bird depredation permit. Permits allow for the lethal take of a limited number of birds by trapping or shooting to resolve a specific damage situation.
The application for a depredation permit requires extensive documentation showing:
- Economic losses caused by the vultures
- Non-lethal control methods attempted before applying for a lethal take permit
- Number of birds requested to be killed
USFWS biologists will evaluate the need for lethal control based on this documentation and may recommend additional non-lethal methods to try first. The permits also require that any vultures taken must be fed to wildlife rehabilitators and not wasted. Proper adherence to the permit requirements allows for limited take with oversight to restrict overuse.
Conclusion
In summary, black vultures were granted federal protection under the Migratory Bird Treaty Act in 1972 after populations declined severely due to eradication programs. These vultures provide valuable ecosystem services by scavenging carrion, but they can come into conflict with humans by preying on livestock. Lethal control requires proper permitting and oversight from the USFWS to prevent overuse. Where possible, non-lethal management solutions allow farmers to coexist with vultures and gain the benefits of their scavenging behaviors. Maintaining vulture populations through legal protections and responsible management allows us to conserve these unique birds and the services they provide.