Lack of snow hampers Yellowstone wolves’ winter hunting season

BILLINGS – A lack of heavy snow has meant a lean winter for Yellowstone National Park’s wolves, according to the crews that annually monitor the park’s packs.

Wolves rely on deep snow to tire out their prey to make it easier to bring down much larger animals like elk and bison. Typically, the deeper the snow the better the hunting for the big canines whose large feet help keep them atop the snowpack.

But according to the most recent U.S. Drought Monitor, the northern portion of Yellowstone, and much of western Montana, is experiencing severe drought. Although winter recreationists like snowmobilers and skiers may be howling about the scarcity, for wolves deep snow can be a matter of survival.

Fewer kills

Here’s one example of the lack of snow’s impact on wolves in Yellowstone. In 20 days of the Wolf Project’s flights in November and December, not one wolf kill by the Mollie’s Pack – which lives in the remote Pelican Valley – was located.

“I don’t know if that’s ever happened before,” Jeremy SunderRaj told George Bumann in a recent Yellowstone Summit interview.

SunderRaj has worked for the Yellowstone Wolf Project for five years. Although he said the Mollie’s pack, consisting of nine adults and four pups, undoubtedly made some kills to survive, none was visible from the air.

“I think the wolves were just struggling taking things because of the lack of snow,” said Taylor Rabe Bland, who has worked with the project for more than two years. “They were traveling very far distances very quickly. Whereas in previous winter studies, they’re making a kill and they’re hunkering down.”

In 30 days of wolf watching – which starts at dawn and ends at dusk – one team of researchers located only seven carcasses wolves had fed on, one of which was scavenged. The wolves were largely dining on bull elk, some of which go into winter weakened by a loss of body fat during the fall mating season. The other team identified eight kills by the Junction Butte pack with 40 kills spread across the park.

“So it certainly has been a tougher winter for wolves as opposed to, like, a year ago when they were doing really well,” SunderRaj said.

Last winter was one of the coldest and snowiest on record. At this time last year, the upper Yellowstone River basin had a snowpack 122% above normal. At the beginning of last month, the upper Yellowstone had 55% of normal. Recent snowfall has bumped that up to 78%. All of the snow and cold prompted a large migration of bison out of the park, more than 1,000 of which fell to native hunters. South of Grand Teton National Park, hundreds of mule deer and pronghorns succumbed to starvation in the brutal weather.

Wolf numbers

The more animals that succumb to winter, the more food there is on the landscape for scavengers and predators. At the end of last year, researchers estimated Yellowstone’s wolf population to be about 124 animals in 10 packs.

“That’s one of the higher populations seen in the park in the last decade or so,” SunderRaj said.

The 8 Mile pack, which roams the Blacktail Plateau, had 18 pups this summer from three to four females. All of the pups survived into winter.

“About 25% of our packs each year for the last 28-some odd years, exhibit what we call multiple breeding, where you have more than one female” birthing pups, said Dan Stahler, Wolf Project leader, in his talk with Bumann. This tends to happen in packs that are more “socially complex” – unrelated animals coming together.

At the end of 2022, the park’s wolf population was estimated at 108 animals. The year prior the population was about 97 wolves. This drop came after Montana relaxed hunting and trapping of wolves outside the park in the 2021-22 season, which saw 25 park wolves killed, 19 of them in Montana.

Since that lethal year, Montana reduced the number of wolves that can be killed outside the park to six. That quota was quickly filled this year, with four males and two females killed near Gardiner. At the end of February, Montana Fish, Wildlife & Parks also sought information on a suspected wolf poaching in the area. In all, Montana has recorded 283 wolves killed by hunters and trappers this season.

The loss of so many wolves, and the park’s repopulation two years later, proves the resiliency of the wild canines to large disruptions in their social dynamics, Stahler said.

Despite the one-year of hunting and trapping loss, Yellowstone’s wolf population has remained fairly stable for the last 11 years, he added, averaging about 100 wolves in 10 packs.

The 8 Mile pack is the largest, with seven adults and 18 pups for a total of 25. On the Northern Range, the Junction Butte pack has the most adults, at 10, with only one pup. In other packs spread across the park, the Wapiti Lake pack that inhabits the Hayden Valley is the largest with nine adults and six pups.

Wolf, elk studies

In a continuing effort to gather more information about Yellowstone’s wildlife, last year the Wolf Project staff began placing remote recording devices across the park. Called the Cry Wolf project, the devices picked up 937 incidents of howling between May and November, Stahler said.

The idea is to test whether the devices, along with other noninvasive means of collecting data, can be used to monitor wildlife. Using artificial intelligence, the acoustic monitoring is being tested to see if individual wolves can be identified, whether they can be counted and if humans can learn to understand what the wolves are saying.

“So we’re very excited about this,” Stahler said.

Next June, his staff is planning to collar 40 elk calves to see where they travel, as well as to monitor their survival and, when killed, find out which predator was responsible. Cougars, bears and wolves all prey on elk calves. The majority don’t make it past their first month of life, Stahler said.

Similar studies have been conducted in the 1990s and early 2000s, providing comparisons across the decades as the presence of predators has grown in the park. Some of the goals include gaining a better understanding of how carnivores compete with each other, how they coexist and still thrive.

The information researchers gather in Yellowstone can be used to help people outside the park better understand and coexist with large predators, Stahler said.

“This is one of the richest data sets of multiple large carnivores coexisting anywhere in the world,” he added.

“We’ve learned more about wolves in the last 30 years than all of the years leading up to that because of the visibility of wolves in Yellowstone National Park,” SunderRaj said.