Reducing the number of vultures and increasing the number of dogs carry serious risks of disease

In the backyards of Ethiopian slaughterhouses, also called slaughterhouses, there is an environmental shift that will respond to similar crises around the world. Species with a clear and effective ecological role are in serious decline, and less specialized but more aggressive species that have emerged to take their place are not only less efficient but also harmful to their ecosystem, which in this case includes man.

It’s a story about vultures, wild dogs, rabies – and piles of rotten carcasses of animals. Fasten. But in the end, it’s about the power of conservation to keep ecosystems, even urban ecosystems, in balance, benefiting the people who live there.

“Consumption of vulture falls is declining and increasing by most other scavengers, but this increase is not enough to compensate for the loss of vultures.” says Evan Buchley, a graduate of the University of Utah who is now a graduate of The Peregrine Fund, “So there’s a gap. And what is happening with this gap is an unanswered question, but that is the problem. “

The study is published in Journal of Wildlife Management and is funded by the National Science Foundation, the University of Utah, HawkWatch International, The Peregrine Fund, and the National Geographic Society.

Vultures are amazing

Worldwide vultures are well equipped to take care of the unpleasant remnants of death. Rotting carcasses can become a source of disease, possessed by bacteria and insects. But vultures are an effective cleanser. By eating the scum, they remove the carcasses and pass them through the digestive system with high acidity, which destroys pathogens. A variety of vultures is better – some species specialize in peeling skin and skin, and others, getting the last, literally swallow bones.

But vultures have been in trouble in recent decades. They are sensitive to the poisons in the carrion they eat, be it lead cartridges, diclofenac or poisons used against predators. And if vultures give birth to relatively few chicks and mature for a relatively long time, they find it harder to recover after a population decline.

Chagan Sekercioglu, an associate professor at the University of Utah School of Biological Sciences, showed that vultures were the group of birds most at risk (the so-called environmental guild if the group uses the same or related resources) in 2004, when he conducted the first known environmental analysis all species of birds during postgraduate studies.

In 2012, Sekercioglu accepted Buchli as his first graduate student at W. Buchli brought extensive experience working with vultures and condors. He and Sekercioglu have launched a project to track Egyptian vultures in eastern Turkey and the Horn of Africa.

“Evan has brilliantly managed this project and extended it to other species of Ethiopian and Horn vultures,” Sekercioglu says. “Despite many challenges, he also decided to study the communities of cattlemen at the Addis Ababa slaughterhouses to quantify the causes and consequences of the decline in vultures in the region.”

In 2016, Sekercioglu and Buchli re-analyzed the ecology of all bird species. “We realized that vultures not only have the fewest species among any bird environmental guild, making them indispensable, but since the first analysis in 2004 they have gone down faster than any other group,” Sekercioglu says.

Yes, there are other types of hackers that can take the place of the vulture at the falling table. But the loss of vultures, as we shall see, can lead to human costs.

Feathered “employees” of the slaughterhouse

Vultures are desirable partners in Ethiopian slaughterhouses. After cutting animals in clean conditions, workers move the remains of carcasses – hooves, organs and bones, for example, in separate warehouses. This. . . a unique sensory experience, Buchley says.

“It can be pretty smelly and pretty rude, by any objective measure.”

So the slaughterhouses are grateful to the cattlemen, including the critically endangered whites, Rupel and hoods, who are eager to clean up the pile.

Co-author of the study Alazar Dhaka Rufu from the University of Addis Ababa interviewed slaughterhouse staff to find out how they treat vultures.

“Some slaughterhouse workers say half-jokingly, but not entirely, that they see vultures as slaughterhouse workers,” Buchley said, citing Rufo’s findings. “They perform an important function. There is an intention behind the system. “

Other winged sinks often visit heaps of recycling, including crows, crows, ibises and marabou storks. Among the four-legged visitors are packs of wild dogs.

“It’s an urban environmental situation where you have an encounter with human food and really interact directly with wildlife food stocks,” Buchley adds. “It’s just a very complex, kind of rough, but exciting system.”

With a research team that includes Rebecca Bishop, Tara Christensen and Sekercioglu of the University School of Biological Sciences, Buchli set out to quantify the amount of falls consumed by cattlemen at six slaughterhouses in Ethiopia over five years, from 2014 to 2019.

Decreased number of vultures and increased rabies

The team noted the types and number of scavengers who visited the slaughterhouse buffets, and used this to extrapolate how much they ate. At first the vultures ate more than half of them in piles of recycling. White backs, Rupel vultures and hoods together ate an average of about 550 pounds (250 kg) per day.

But by the end of the five-year study, the number of Rüppel vultures and white backs visiting the slaughterhouse disposal plant had fallen by 73%. Visits to the vulture decreased by 15%. At the same time, the detection of wild dogs has more than doubled.

“While we can’t say for sure whether population decline is a collapse of the population or if vultures are displacing dogs and moving away from slaughter, in any case, this is a real concern,” said Megan Murgatroyd, interim director of international programs for HawkWatch International.

“We know that vultures are declining, and we know that wild dogs are increasing, but we don’t know exactly why,” Buchley said, adding that practice at the slaughterhouse is also changing and that more research will be needed to determine the cause. and-effect relationship.

Regardless, vultures cannot afford to lose a slaughterhouse as a food supply. Rupel, white-backed and hooded vultures are listed as endangered. “This is the highest category of threat before disappearing or becoming extinct in the wild,” says Buchley.

Over the last three generations (approximately 40 years), the population of the Rupel vulture has declined by more than 90%. The white and hooded vultures go a little better, but not much. They are estimated to have fallen by 81% and 83% respectively over three generations.

“Therefore, it seems that their disappearance from the slaughterhouse is most likely due to falling population,” – says Murgatroyd. “Vultures need all the help they can get right now, and competition with a growing dog population is only making matters worse.”

Other monuments that have increased, including dogs, ibises and crows (crows and crows), have failed to pick up slack in the slaughterhouse. By 2019, cattle consumed nearly 43,000 pounds (about 20,000 kg) per year less than in 2014, when there were more vultures and fewer dogs.

A terrible consequence of an increase in the number of dogs can be an increase in rabies in humans. In the late 1990s, vulture populations in India and Pakistan declined. The population of wild dogs has increased to take advantage of the uneaten carrion.

“They’re also carriers of disease,” Buchley says, “and they interact very closely with people. And there was a link between the big jump in the wild dog population and the rabies in India. ”

Could the same thing happen in Ethiopia? Scientists have not yet found a link between the loss of vultures and the rise of rabies in this country. But Ethiopia already bears a heavy burden of rabies with about 3,000 deaths from the disease a year.

“Unlike many diseases that affect the elderly, rabies disproportionately affects young children, who are most often bitten by rabid dogs,” says Buchley.

Dog fencing

Researchers give a simple recommendation to help the situation: use fences to prevent dogs. And many slaughterhouses are already fenced.

“But the pack of wild dogs is really persistent,” Buchley says. “It’s hard to keep hungry animals from a lot of food.”

Dogs can fight and dig their way through many fences, and maintaining or strengthening them can reduce the profits of slaughterhouses.

“It’s a question of weighing how important it is to keep fences in good condition,” Buchley says. “Improving these fences could really bring great benefits.” These include the potential reduction in the number of wild dogs that breed rapidly and whose populations keep pace with available food. This, in turn, can help control rabies in humans and disease in other animals, such as the critically endangered Ethiopian wolf, which is transmitted by wild dogs.

And, oddly enough, fencing off a large number of dogs can increase falling consumption rates. Without dogs around to scare away other scavengers, vultures could return in larger numbers to more quickly and efficiently clean up dumps.

“It can lead to less odor, less groundwater pollution, fewer insects such as flies that can breed on carcasses,” Buchley says. “There are many potential benefits of investing in repairing fences around slaughterhouses that exist across Africa and elsewhere. We call on slaughterhouses, local authorities and international organizations to take this into account when looking for solutions for waste disposal, human health and waste management. ”

The results of the study show that the loss of specialized species from the ecosystem cannot always be compensated by other species.

“The main point is that vultures are very important,” Buchley says. “If they decrease, we expect that there will be quite serious environmental consequences and the severity of human diseases may increase. And that’s why we have to respect vultures and invest in their preservation. “

Reference: “Reducing debris clearance by endangered vultures in the Horn of Africa” ​​by Evan R. Buchley, Megan Murgatroyd, Alazar Dhaka Rufa, Rebecca S. Bishop, Tara Christensen, Peter P. Mara, T. Scott Silet and Chagan Hakkio February 13, 2022, Journal of Wildlife Management.
DOI: 10.1002 / jwmg.22194