A pack of wolves in western Wyoming killed 19 elk in what is known as an extremely rare "surplus killing." Wildlife officials found the carcasses of 17 calves and two adults on a snowy plain near the tiny town of Bondurant.
Predators such as mountain lions, bears and wolves are known to engage in surplus kills, taking down more prey than they can eat and abandoning the rest. And while it is not unusual for wolves to kill one or two elk a night in that part of the state, having killed 19 in one night is rare.
"It's rare at this magnitude," said John Lund, regional wildlife supervisor for Wyoming's Game and Fish Department. "We've documented it before but have not documented it to that extreme."
Lund said the culprits might be a pack of nine wolves known as the Rim Pack. Wolves, however, are protected under the Endangered Species Act, so there is nothing the state can do about them or their mass killings.
"We can't take any action proactively," Lund added. "It's frustrating for state wildlife management."
Biologists and wildlife officials explained that wolves tend to kill more than they can eat during the winter, when frigid temperatures preserve the killed prey for later consumption.
Prior to this surplus killing, there was an estimated 1,100 elk living in the area. Lund said that pack of nine wolves is allegedly responsible for about 70 elk kills this winter, which is more than average and enough to affect the hunting season for humans.
"We're not sure what triggers surplus killing," Lund said, "because in many cases predators will kill with the intent to eat, but in this case something triggered and they went crazy and just took down each elk and moved on to the next."
Sometime such large-scale killings are referred to as "sport killing," but wolves are not known to hunt for sport.
"By and large, wolves don't kill for sport. What we found is that generally wolves did not kill what they did not eat," said Mike Jimenez, Northern Rocky Mountain wolf coordinator for the U.S. Fish and Wildlife Service (FWS).
Officials say factors such as deep snow or disease could have made the elk herd particularly vulnerable, triggering the surplus killing. The next step will be to test the elk carcasses for illness.
Others suggest the wolves night have been stocking up to prepare for leaner times when they had the chance.
"They're like a person living day to day, getting enough to survive. When prey is vulnerable, they don't have that mechanism to stop," said Ken Mills, the state's carnivore biologist. "If someone is barely making it day to day and they walk into a buffet, they're going to eat like it's a buffet."
After being brought to the brink of extinction in the first half of the 20th century and being declared endangered in 1978, wolves have made a remarkable recovery in the U.S.
In 2014, an estimated 330 wolves roamed Wyoming. While the state has argued to take wolves off the list of endangered species, the animals remain off limits to hunters.
