The depicted scenes of farmland in Indiana and elsewhere seem to spring from a page of a horror novel, with black vultures descending into the forests and pastures of the Midwest and beyond.
Farmers tell of fierce attacks on their animals: wakes of large, dark birds with stooped shoulders feasting on newborn calves as they come out of their mothers, and sometimes preying on the mothers themselves.
“Over the last couple of years, they’ve gotten really aggressive,” said John Hardin, a cattle breeder from Scott County, southern Indiana, about 20 miles north of Louisville, Ky. who often sees eight to ten birds on his farm. At least two of his calves were killed by vultures, maybe more. “They love the navel area and they will bring it to the bone and hide.”
Vultures are often referred to as “nature’s garbage cans” because their highly adapted digestive and immune systems allow them to eat the carcasses of dead and sick animals with impunity. While recovery is considered an essential ecosystem service, reports of black vultures preying on live animals are relatively unknown, some experts say, and some have expressed skepticism about predation.
The situation in Indiana this summer proved alarming enough that farmers are now allowed to quickly obtain permits – acquired from the US Fish and Wildlife Service by the Indiana Farm Bureau – to “take” or kill, until ‘to three birds, a recently launched program. force in other Midwestern states.
“These migratory birds cross the Ohio River,” said Greg Slipher, breeding specialist at the Indiana Farm Bureau. “I got a warning from my counterpart in Kentucky, and he said, ‘They’re coming to you’ and he was right. Over the past three or four years, we’ve gone from a few reported incidents to many. “
Much remains unknown about the bird and why its numbers are increasing in states where they were not seen ten years ago. They have traditionally been found in the southern United States and Central and South America, and it is not known why they have significantly extended their range north and west. Some believe that milder winters due to climate change could be a factor.
From 2007 to 2019, breeding populations of black vultures increased at rates of 1% to 4% per year across the species’ range in the United States, with the exception of small portions of the coast. of the Gulf and South Central Florida, according to a report analyzing EBird data by the Cornell Ornithology Laboratory.
The extent of predation by black vultures is far from settled as they have moved to new territories. One of the country’s leading birders is very skeptical and expressed concern about the permissions granted to kill them. Black vultures are one of some 1,100 species protected under the century-old International Migratory Bird Treaty Act; Harming them without a license can result in hefty fines or even jail time.
“I’m going to take an extreme stance here and say they don’t kill healthy calves,” said John W. Fitzpatrick, recently retired director of the Cornell Lab of Ornithology in Ithaca, New York.
For seven years he led the Archbold biological station in Central Florida, which includes a working cattle ranch where black vultures were present. “They are often seen around struggling calves that are stillborn or dying and they jump on them quickly,” he said. But, he added, “the idea that they are predators of cattle is wrong.”
“In my opinion, this should be considered a tradition because it is not well documented,” he said. Vultures can sometimes attack a healthy calf, he said. But, “are we really talking about something that is so prevalent and economically destructive that we have to start allowing the destruction of a protected bird?”
Vultures are large birds, weighing nearly five pounds, topped with what looks like a helmet of gray skin and no feathers. They have a large wing span of up to five feet, which gives them loft as they soar over thermals and spot their prey. They are one of three species of vultures in the United States; the turkey vulture and the endangered California condor are the other two.
“The black vulture is an incredible bird,” said Dr. Fitzpatrick. “They are faithfully paired, have amazing and complex social demeanors, and are super intelligent. They closely guard the nest. The eggs hatch and become these fuzzy white chicks, and for a month or six weeks you may always find that there is a nest nearby as one of them is sitting day after day, week after week, at the same place.
Dr Grant Burcham is a veterinary diagnostician at the Heeke Animal Disease Diagnostic Laboratory at Purdue University, which operates a bovine research farm.
Dr Burcham said he received a calf killed by vultures and euthanized two others which were attacked. Autopsies showed the calves were not healthy – two had “diarrhea”, bowel disease and the third a broken leg – and may have been selected by vultures who sensed their vulnerability. “The animals were dehydrated and would have been noticeably slow, which is why they were likely targeted.”
A recent paper concluded that the incidence of predation by scavenging birds in Argentina, including the black vulture, although perceived to be frequent, was not at all common.
Patrick Zollner, professor of ecology at Purdue University, agreed that there was a lack of empirical evidence for predation. “What is totally unknown in Indiana and in most places is how often this happens,” he wrote in an email. “Closing this gap is one of the goals of our ongoing research. “
Marian Wahl, a doctoral student with Dr Zollner at Purdue, who studies birds in Indiana, said she believed black vultures numbered in the millions in the United States, and that in Indiana they passed from a few decades ago to around 17,000 now.
While the US Fish and Wildlife Service can issue special permits to kill damage-causing birds, the process to obtain them can be long and cumbersome and cost $ 100 each. The relatively new program in Indiana and elsewhere allows state agricultural offices to obtain a large number of permits and issue sub-permits, which experts say is more responsive.
Slipher said he has received 45 applications for a “take” permit and authorized 22 since the program came into effect in early August.
Although the permits allow each person to shoot three birds, Slipher says there is a better strategy.
“I advise not to go there and shoot all three on the first day,” he said. “One of the things we do know about this particular species is that it reacts greatly to effigies of its genus. We encourage our producers to shoot this first bird and hang it as an effigy. “
It’s an approach that has helped Kentucky’s hardest hit growers – somewhat. Although both real and fake hanging effigies are widely used to disperse birds and studies show that they work, their effectiveness is not well understood.
“If you use an effigy to scatter a perch, does that keep them away from the cattle, or does they just move to a perch on the road and return to the same farm?” Mrs. Wahl asked.
Joe Cain, of the Kentucky Farm Bureau, said black vultures began to appear in his state in the early 2000s, and that in 2015 Kentucky began the new licensing system that had just been instituted in the ‘Indiana.
“We’re only touching the hot spots,” Mr. Cain said. “Those with the most serious problems are the ones who call us. There is a lot more depredation, but at least they know there is a program to help them protect their cattle.
The permits did not significantly reduce the number of cattle killed, officials said. In Kentucky, around 500 to 600 cows a year are killed, they noted, adding that more lambs, kids, free-range chickens and turkeys have been slaughtered as vulture populations increase.
Other tactics include making noise with devices such as propane cannons, firing pyrotechnics, squirting birds with high pressure hoses, and using guard dogs. Because vultures often perch in tall, dead trees to survey the landscape and search for prey, chopping down these trees can also provide relief. The effectiveness of these measures is part of the study that Ms. Wahl and Dr. Zollner have undertaken.
Mr. Cain would like to see federal law changed to help farmers. “We have asked Congress for a safe harbor provision,” he said. “If they see depredation happening, it’s unreasonable to say, ‘I’m going to go home and apply for a permit and wait two days and get the permit.’ When they see this happening, then it makes a lot more sense to protect your livestock. “
A vulture’s attack on living prey is a grim scenario, farmers say. “Birds concentrate during birth – basically at the most vulnerable time,” Slipher said. “Literally, as the calf comes out of its mother, black vultures attack the calf and attack the mother. “
The bird often chooses the eyes, nose, mouth and navel. Farmers say every animal that dies is valued at $ 1,000.
They’re a nuisance for other reasons as well: they tear asphalt shingles from homes, tear off windshield wipers and rubber seals around vehicle sunroofs, and tear seat covers on farm equipment and vehicles. boats.
Their stomach acid is almost as corrosive as battery acid, and their droppings, urine, and vomit can eat away at roofs, towers, and other places they roost.
But vultures are also a proven and essential part of the ecosystem. Massive vulture deaths have occurred in India, for example, due to the widespread use of a veterinary drug toxic to birds. This led to an increase in rabies. Vultures used to clean up dead livestock and other wastes; when they disappeared, the dogs began to feed on the waste, and as their numbers increased, the incidence of rabies also increased.