Study shows slight effects from wolves at elk areas
By MIKE STARK
Gazette Wyoming Bureau
For wolves in winter, Wyoming’s elk feed grounds near Jackson must seem like a giant, open-air smorgasbord.
But the wolves aren’t overindulging, and the elk aren’t being driven out of the area, according to Mike Jimenez, the U.S. Fish and Wildlife Service’s wolf coordinator in Wyoming.
“These elk have adjusted to wolves being around,” Jimenez said. “Even though these are very accessible elk (to wolves), we’re not seeing any kind of mass killing. They’re not slaughtering the elk and they’re not chasing them off forever.”
Jimenez and others have spent three winters watching wolves and elk interact on the Alkali, Patrol Cabin and Fish Creek feed grounds in the Gros Ventre River drainage outside Jackson. About 800 elk were fed hay during the winter at each feed ground.
When wolves were reintroduced to Yellowstone National Park in 1995 and 1996, many feared that the predators would flock to the elk feeding grounds to kill large numbers and force elk out of the area.
“That became a real hot issue right off the bat,” Jimenez said. “But it hasn’t happened.”
Biologists primarily tracked two wolf packs in the area, the Teton and Gros Ventre, and observed the elk they killed and how the species dealt with one another.
Over three years, researchers located 119 elk that were killed by wolves on the three feed grounds and adjacent areas. The average age of the adult elk that were killed was 10; the oldest was 23. Forty-three percent of all the elk killed were cows and 53 percent were calves.
Fourteen elk were deemed “surplus kills,” in which wolves left much of the meat behind.
“There are not that many occasions when wolves kill for the fun of it, despite what a lot of people think,” Jimenez said. “It sometimes happens, but it’s not a rule of thumb.”
The rate at which wolves are killing elk on the feed grounds is similar to how wolves kill elk in Yellowstone National Park, he said.
Beyond how much the wolves were eating, researchers also wanted to know how elk on the feed grounds reacted when wolves showed up.
At Alkali and Fish Creek, elk often scattered and regrouped at the Patrol Cabin feed ground. But when wolves made a kill at Patrol Cabin, the elk would either leave and return after a few days or simply stay put.
Jimenez said the behavior could be connected with how much snow is on the ground and what kind of tree cover wolves had to hide in.
“We speculated that elk congregated in larger herds as a predator defense strategy,” he said. And elk may have preferred Patrol Cabin because there was less snow cover and better visibility to see approaching predators.
He noted that last winter the cow-calf ratio, which is often used to help determine the overall health of the herd, dropped from a five-year average of 24 calves per 100 cows to 17 calves per 100 cows.
The overall trend for the last 10 years has been a decline in that ratio with a few minor ups and downs, Jimenez said. It’s too early to tell what the numbers from last winter mean and how much wolves can be blamed for the decline. In Yellowstone, biologists have attributed declining rates to several factors including wolves, the ongoing drought and past severe winters.
“We’ll have to wait and see what the trends do,” he said.
Jimenez said the winter study also couldn’t help predict whether wolves would drive elk off other feed grounds in the state and onto private property, which has been a concern especially in the Pinedale area.
Anecdotal evidence from the Gros Ventre area indicates that elk stick close to the feed grounds even when wolves arrive because the grounds are a time-tested food source for the elk.
“When we saw elk move, it was often a short-term move,” Jimenez said.
The study of wolf-elk interaction at the feed grounds is continuing this year.