Hunting, fewer pups and disease worked together to nudge the region’s population downward, biologist says.
By Mike Koshmrl
A dearth of wolves in places like the Gros Ventre River valley this winter was not an anomaly, as wildlife managers are reporting reduced numbers throughout wolf range in the state.
The overall Wyoming wolf population, estimated at 286 as the calendar turned to 2019, was down 61 animals from a year ago. That’s the fewest animals counted since the Wyoming Game and Fish Department took over management and initiated hunting seven years ago.
Yellowstone National Park’s wolf numbers, 80, are as low as they’ve been since the late-1990s reintroduction era, due largely to a pack that shifted to territory out of park boundaries. Elsewhere in the state a combination of forces drove down the abundance of Canis lupus, Wyoming Game and Fish wolf biologist Ken Mills said.
“You have multiple factors working together this year, of wolf hunting, natural mortality and reduced pup production,” Mills said. “All three of those work together to explain why we have smaller pack sizes … and fewer wolves.”
Game and Fish released a monitoring report Tuesday that detailed how the population fared over the last year. The U.S. Fish and Wildlife Service required the annual assessment for five years running when the agency delisted wolves in the Equality State, deeming them recovered and no longer in need of Endangered Species Act protection.
Although having fewer wolves concerns wildlife watchers and activists, the outcome is what Wyoming managers have been seeking.
The Wyoming Legislature went over Game and Fish’s head more than a decade ago to mandate an expansive “predator zone” in 85 percent of the state, where wolves are classified as varmints that can be killed without limits or rules. Despite a propensity for preying on livestock and in turn being killed by hunters and managers in those places, a minimum of 44 wolves persisted there, generally residing along the periphery of the greater Yellowstone region.
Another 10 wolves called the Wind River Indian Reservation home during Mills’ midwinter assessment.
The balance of Wyoming’s wolf population lives in the “trophy game” area, in the Yellowstone region’s core outside the national parks. Here, Mills and his fellow managers have the most control over numbers, and they use hunting as the primary tool.
Game and Fish has a long-held population goal of 160 wolves in that region, a count that, models say, is as low as the state can go while still ensuring that 10 federally required breeding pairs remains on the landscape. This year the count came out at 152, a 23% dip below 2018’s count of 198 wolves. Wyoming officials tallied 13 breeding pairs within their jurisdiction, although two of those pairs resided within the predator zone.
“We still met our minimums,” Mills said. “It gives us a high confidence that even in a bad year, we’ll still be OK.”
Mills qualified “a bad year” as one where relatively few wolf pups are born and survive, and the population “underperforms” models that predict where things end up.
Natural wolf deaths in 2018 were higher than usual, and included seven animals killed in territorial battles, five pups from the former Horse Creek Pack that died of mange and one wolf that starved after an injury.
But as is the case every year, various human causes of death explained the vast majority of wolf mortalities. About half died from hunting; more than a third were culled after deadly run-ins with livestock.
Some 172 wolves within Wyoming’s boundaries were known to have died last year, a count that Game and Fish estimates is 47 percent of those that were alive, not counting pups. Although the figure sounds high — essentially every other adult wolf died last year — Mills said it’s not out of the ordinary and illustrates the large carnivore’s resilience.
“Three years in a row,” he said, “it has been above 45 percent.”
At a pace much greater than the population decline, documented conflicts between wolves and domestic animals also fell off last calendar year.
Game and Fish chalked up 54 cattle, 15 sheep and a horse as having succumbed to wolf predation. Cattlemen lost roughly half the stock they did in 2017, and a third of what was documented in 2016. Woolgrowers, likewise, dealt with only about a fifth the predation that was reported the previous two years.
“That’s part of the point of why we’re reducing wolf populations,” Mills said. “Sheep conflicts are low because wolves are largely being removed from areas where sheep exist. Cattle conflicts have decreased as the population decreased.”
Wolf packs in the Jackson Hole area were typically dynamic over the last year: New packs emerged, some shifted territories and others were killed or dissipated.
Avid wildlife watcher Lisa Robertson said it was a grim winter for viewing wolves in their usual Jackson Hole haunts.
“Until now, I’ve never not seen a wolf in all the winters I’ve lived here,” Robertson said. “There hasn’t been any. It’s been a very sad situation.
“This summer we’re going to see what kind of hit they took,” she said. “We go out in the summer every week. How’s this going to affect our recreational opportunity?”
Two of the most regularly watched Jackson Hole wolf packs are still around, Mills said
The Pinnacle Peak Pack, which dens on and frequents the National Elk Refuge, registered eight animals in the annual report. The Lower Gros Ventre Pack, which has assumed the territory of the former Phantom Springs Pack along Grand Teton National Park’s eastern boundary, also wound up at eight wolves during midwinter aerial assessments.
Notable local packs that disappeared last year included the Slate Creek Pack, denizens of the lower Gros Ventre area that numbered a dozen one year before. Reasons for their demise include hunting, wolves that were shot and not recovered, animals that dispersed and the bloody aftermath of clashes with cattle, the report said.
South of Jackson, the Horse Creek Pack also winked out. A bout of mange did in the pack’s lone litter, and other members were killed by hunters or dispersed.
In both places, though, new small packs are taking advantage of the vacated territories. Up the Gros Ventre, the Lightning Pack has been using areas where the Slate Creek wolves once roamed, although the new pack was cut down to just two animals after hunters killed four of its members.
And the newfound three-member Game Creek Pack is filling the niche that the Horse Creek Pack once occupied, Mills said.
“They’re pretty dynamic,” Mills said. “They know their neighbors. They know their neighbors’ weaknesses, and they probably know how many there are and the composition of their neighbors.
“When openings emerge, they take advantage,” the wolf biologist said. “If they can do something to increase their chances of survival, then they do it.”