Yellowstone Wolf Project collars 23 wolves in winter study

YELLOWSTONE NATIONAL PARK — Dating back to when wolves were reintroduced into Yellowstone National Park (YNP) in 1995, wolf biologists have been performing an annual wolf capture project to study behavior, eating habits, predation, movement, pack dynamics, survival rates and population numbers.

The Yellowstone Wolf Project is a helicopter operation, led by lead wolf biologist Dan Stahler, and this year the team captured and radio collared 23 wolves from seven different wolf packs in YNP from Feb. 19 through Feb. 22.

“In the early years of wolf recovery, we were mandated to monitor wolf species under the Endangered Species Act,” Stahler told Buckrail.

Since the delisting of wolves in Wyoming, The Yellowstone Wolf Project continues to use radio collars as a monitoring technique, and the goal is to have the same number of collars in every wolf pack in the park.

“When we do these wolf capture operations, I’m in a helicopter…I’ll dart a wolf and wait for the immobilization drug to take effect, usually in five minutes,” Stahler said. “We get dropped off with the wolf when it’s sedated and safe to handle. We put a collar on, take a blood sample for genetic and disease analysis, we weigh and measure it and collect biological data. In about 30 minutes, the wolf wakes up, and usually the next morning it’s back with its pack. That allows us for the coming years to maintain contact with that individual wolf.”

Stahler explained that only one or two wolves in a pack are collared and that research has shown that collars have a minimum impact on the animal. Once the location of a single wolf is determined with a collar, the rest of the pack is typically nearby. The biologists use radio collars to monitor social dynamics, annual counts, pack size, den location, pup size and litter production and territorial disputes with neighboring wolf packs.

GPS collars are also used in the Wolf Project, and these collars store data which is then sent remotely to a computer on a routine basis. GPS provides more specific information like food habits, interactions with scavengers and predation patterns. During these winter studies, field crews will observe a wolf pack for 30 days to determine what they feed on and how many prey animals are killed.

Stahler emphasized that biologists are currently developing less-invasive technology to study wolves. For instance, the Wolf Project is starting to utilize bio-acoustic studies, where 24/7 recording devices are placed across the landscape, and artificial intelligence (AI) is used to process large amounts of data. Specifically, the audio recordings and AI can detect how many wolves are howling in a group, the ages of the wolves, the unique vocal signatures of individuals and the sounds of a particular pack. Remote cameras are also placed in the Park to monitor the animals.

All the gathered data is beginning to dispel certain myths about wolves.

“The reality is, there’s still a lot of misinformation about wolves, and we think it’s really important to provide data to make decisions, guide policy and understand their biology and behavior,” Stahler said.

Stahler said that wolves rarely kill for fun or leave prey after killing it.

“Wolves do not have the luxury to kill anything they want, at anytime they want,” Stahler said. “Hunting wild prey, hunting elk and bison, is a difficult and dangerous task. Wolves are limited by their biology and by their mouths to grab onto an animal 10 times their body weight. They work in groups, but it’s very difficult for them to feed themselves…they need vulnerable prey to be successful, an older elk or young calf. A prime aged animal is virtually invincible to wolf predation. Each year, we document wolves that die from hunting large prey, they get stomped on and gored.”

Stahler told Buckrail that during severe winters with deep snow, there have been instances when a pack can take down more than one elk, but they almost always come back to complete the feeding. He said that there have been cases of wolves going into a sheep pen and killing 20 sheep in one night, but that is not typical behavior.

“Every few years you will hear a new story because it’s sensational, ‘Oh look what the wolves did,’ Stahler said. “But to characterize that as how wolves hunt, and what they typically do in nature is just not true.”

According to Stahler, there are tools available to manage wolf livestock conflicts, including deterrents like live stock guarding dogs or the lethal removal of problem wolves.

There is also the misconception that wolves always mate for life.

“They don’t live that long, the average life span is five to six years,” Stahler explained. “It’s hard being a wolf in the wild. They die for various reasons, human-caused and natural, and a mate will be replaced if needed. As long as the wolves survive, they will maintain a pair bond.”

Typically, wolves live in social packs with a matriarch, patriarch and off-spring from multiple litters. However, approximately 25% of Yellowstone wolf packs consist of more socially complex families; with multiple females giving birth or a dominate male breeding with more than one female as long as they aren’t related. Over evolutionary time, wolves have developed strategies to avoid inbreeding, according to YNP. The Eight Mile pack is one of the largest packs in the park, with approximately 25 wolves, 18 of which are pups that were born in the summer of 2023 to three different females.

Biologists have said that wolves and predation play an important role in the Greater Yellowstone ecosystem, including mitigating the spread of chronic wasting disease.

“Predation is an important ecological force that has shaped life on earth for millenniums; the speed of a pronghorn, the strength of an elk and the behaviors that we admire in animals is shaped by predation,” Stahler said. “When you have an animal like a wolf exerting that top down predatory force…it helps to transfer nutrients and energy from herbivores that feed on plants back into the food web. When you have those links of predation; herbivory, scavenging, plant productivity and growth as part of a landscape, we find that these ecosystems are more resilient to environmental changes, prey populations are more regulated and it helps to cull weaker and sick animals.”

Lastly, Stahler shared the economic benefits of keeping wolves in the park, “Wolves are now one of the main reasons people come to visit YNP,” he said.

According to the Greater Yellowstone Wildlife Related Activity Valuation Study, it is estimated that “direct spending in 2021 by YNP visitors who would not have visited the park without the presence of wolves is at least $82.7 million.”