Among some people wolves have a reputation of being super killers, able to wipe out wildlife like deer and elk when they move into a territory. But that’s simply not true, according to Dan Stahler, a wolf biologist in Yellowstone National Park.
“There are limits to their ability,” he said during a Facebook Live broadcast Tuesday.
“There is a lot of misinformation out there,” Stahler said, so he attempted to dispel some of the myths with his talk.
The talk is one of five the park has scheduled on Facebook Live every Tuesday at 11 a.m. throughout the month of March.
Stahler has been studying wolves in the park for 23 years. In that time he’s examined animals that wolves have killed, conducted necropsies on dead wolves and watched wolf interactions with bison and elk while conducting scientific studies.
There are now about 20,000 to 30,000 elk that utilize different parts of Yellowstone in six to seven different herds, Stahler said.
It’s well known that elk numbers in the park gradually plummeted after wolves were reintroduced in 1995, but he said that population decline wasn’t solely due to wolves — although elk make up anywhere from 80% to 90% of their diet.
Other factors in the elk population decline included elk hunting outside the park, drought, harsh winters, and growth in cougar, grizzly bear and black bear populations.
“Wolves have definitely been a major player,” he said, but they are just one of several factors.
Wolves need vulnerable prey — the sick, old or young — to be successful, he said. At this time of the winter, bull elk are in more danger as their energy reserves have declined. Cow elk, on the other hand, are “virtually invulnerable” between the ages of about 2 and 12, he added.
Wolf packs are only successful about 5% to 15% of the time. Packs with 2- to 3-year-old wolves tend to be more successful because at that age they are in peak physical condition. By age 6 that hunting ability has dwindled, he added. Larger packs are also more successful hunters.
Thanks to wolf kills, other scavengers and predators in Yellowstone also benefit, Stahler said — everything from ravens to golden eagles, coyotes and bears dine on wildlife that wolves have brought down.
Overall Yellowstone National Park has a much healthier ecosystem since wolves were reintroduced, Stahler said, and the elk have learned to adapt to the predator risk.
Kira Cassidy, a wildlife research associate with Yellowstone Forever, has been working in the park since 2007. She said the large basins like the Lamar Valley have made it much easier for scientists like her to collect information.
“Because we’re able to see them so often … we get to recognize individuals,” she said.
She noted that group living, such as wolf packs, is unusual among species, with only about 2% of species utilizing the power of several individuals for protection and food.
The average wolf pack size in Yellowstone is 10, with the largest — the Wapiti Lake pack — numbering 15. Often those pack members are relatives, although they do occasionally allow lone males to join — probably because of their hunting ability, she said.
Cassidy ticked off five reasons why wolves live in groups:
1) Maybe the most obvious reason is for hunting. Ideally, four wolves are needed to hunt elk, she said. For bison, a much larger animal, nine to 12 wolves have a better chance of success.
2) All members of the pack pitch in to help raise pups, which are born in April. During that still cold time of the year the mother must remain with the pups to keep them warm. That means she relies on the other members of her clan to bring her food. Cassidy said in the spring a hormone increases in all of the wolves’ blood that makes them want to take care of the pups.
3) When a wolf gets sick with something like mange, they are more likely to survive if they are in a bigger pack. One female in the Junction wolf pack contracted mange and lost much of her hair, but eventually recovered and is now 7 years old and the biggest wolf recently caught. When captured, the researchers also discovered her left eye was damaged.
“Wolves are incredibly resilient,” she said, especially if they can stay with their pack when injured or sick.
4) Packs are the best way for wolves to compete with other scavengers. Although an adult wolf can eat 20 pounds of meat, a small pack will still leave plenty of meat on a carcass that may be lost to other predators. So a mid-sized pack is typically best suited to utilize all of the animal it kills.
5) Wolves are territorial and will kill members of other packs, accounting for half of all wolf mortalities in a typical year. Packs therefore help protect pups and other pack members. In a bigger group, the wolves are pretty safe when they are together.
Stahler said one of his most significant memories of working with wolves in Yellowstone began in his first field season in 1997. That spring he got to observe a litter of wolf pups and how they interacted with other pack members.
A wolf from that Rose Creek pack was later collared but left the area. In 2002 the wolf was discovered in the Bechler region, the southwestern corner of the park, starting a new pack. That white wolf, No. 192, lived to age 12 and successfully colonized a new region of the park.
Cassidy said she has been impressed over the years by the Mollie pack, which has stayed together for 25 years. Members of that pack have included some very strong females, she said. It’s believed that wolf pack territories are matrilineal, meaning they are based on the females’ heritage.
“I admire that long line of females,” she said.