JWM: Eagle predation on livestock is increasing in the Midwest

Black eagle predation of livestock may not be reported. Credit: Joshua Rapp Learn

The idea of ​​a herd of vultures carrying a cow may seem like a silly fantasy, but as black vultures expand north into the United States, it may not be far from reality.

Historical range of black eagles (Cragibs Atratus) usually covers South and Central America. But a warmer climate could lead these scavengers to new areas of the Midwest. These newcomers are slightly larger and more aggressive than turkey vultures (Cathartes’ aura) is widespread in most parts of the United States. In fact, black vultures can become so aggressive that wildlife managers began hearing some “horror stories” about black vultures feeding on newly born livestock starting in the early 1990s.

“[Wildlife managers] “I was really concerned,” said Brandon Quinby, a conservation biologist at SUNY Copleskill.

Quinbee, who was a postdoctoral researcher at Purdue University when this work began, decided to study this emerging problem more closely. In a study recently published in Wildlife Management Journal With funding from the USDA’s National Wildlife Research Center—part of the Wildlife Services—and the U.S. Fish and Wildlife Service, he and colleagues combined data about vultures’ habitat with information about livestock farming to create a model that quantifies the relative risks of these types of predation events that occur in certain areas.

Both black eagles and turkeys are attracted to the remains left when cattle are born – the birds have been known to feed on cattle placentas. Conventional wisdom says that black vultures often scare turkey vultures to get more from the meal. But they don’t always stop at the remnants of childbirth. Reports indicate that raptors will also prey on newborns, starting with the navel, eyes, tongue, anal cavity, and hooves.

“They will certainly attack the young and the weak,” Quenby said. Sure, vultures do not carry livestock, but these attacks can sometimes lead to death.

Often this will start with two or three eagles, but will eventually join more. Reports revealed that vultures will attack cows, goats, sheep, horses, farm-raised deer and domestic pigs.

Quinbee said livestock producers’ reports of such events have increased dramatically. Between 1990 and 1996, for example, farmers reported 115 conflicts between black vultures and cattle. In 2010, the US Department of Agriculture reported that vultures killed 11,900. Since it is difficult to determine whether a young animal was stillborn or born healthy before the vultures went to work, researchers suspect that this type of wildlife struggle did not take place. Report it adequately.

Black vultures are widespread further north in the United States, in part due to a warming climate. Credit: Joshua Rapp Learn

In their models, Quinbee and colleagues combined reports of livestock predation down to the zip code level, which occurs in an area of ​​six Midwestern states including Tennessee, Kentucky, Illinois, Missouri, Ohio and Indiana. They considered factors associated with each area including the location of the report, the type of ecosystems nearby, and whether there is human infrastructure or presence around it. The researchers entered USDA data on livestock density and information on potential nearby vulture roosting sites into their model to help determine which zip codes were the most likely conflict sites.

The team found that across the area, there was not a single zip code where there was no risk of vultures attacking livestock.

“Even in areas where you wouldn’t think of a large livestock population, there were potential small operations,” Quenby said. These small livestock operations mean there is a certain level of risk almost everywhere.

The relative risk ranged from 15% to 63% depending on the region. The greatest danger occurred when the surrounding area had most of the features that give rise to vultures – things like dams or wetlands that vultures usually prefer. Unsurprisingly, areas with a lot of livestock in open pastures were also more susceptible to predation by vultures.

Quinnby said this research could help agencies like Wildlife Services determine where they might focus on preventative measures. Scamming eagles can be tricky, because the birds are subject to the Migratory Bird Protection Act. Commonly implemented mitigation measures in these areas may include the use of guard dogs, fireworks, or laser pointers to scare black vultures away during the cattle calving season. Quinnby said that hanging a doll of a dead eagle on a nearby tree also appeared to repel living creatures. But he said these measures should be taken in coordination with the Wildlife Service or the Animal and Plant Health Inspection Service.

This article contains research published in a peer-reviewed journal from TWS. Individual online access to all TWS press articles is a benefit of membership. Join TWS now To read the latest research on wildlife.


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