By Libby Riddle, UM News Service
YELLOWSTONE NATIONAL PARK – Snow crunched underfoot as Mark Hebblewhite scanned the ridgelines of Canada’s Banff National Park. It was 1995, and the young biologist, fresh out of undergrad, was trailing one of the park’s most elusive wildlife species – the gray wolf.
Though rare to see, the wolves of Banff had radio collars that allowed biologists like Hebblewhite to track their movements from many miles away.
Meanwhile in Montana, 14 Canadian wolves were already on their way to a new home. Following an Environmental Impact Statement by the U.S. Fish and Wildlife Service – for which over 160,000 public comments were received – the federal government approved the reintroduction of wolves to Yellowstone National Park. Spectators lined the road to the north entrance of the park and cheered as trucks carrying the wolves passed under the park’s famed Roosevelt Arch. It was a homecoming decades in the making.
Thirty years later, Hebblewhite is a professor of ungulate habitat ecology at the University of Montana. He and the University’s W.A. Franke College of Forestry and Conservation have collaborated with the Yellowstone Wolf Project for over a decade. The project, which is funded by the nonprofit Yellowstone Forever, is a collection of ongoing research projects and monitoring efforts since the reintroduction. After his time tracking them in Banff as a young man, Hebblewhite dedicated his career to studying wolves and their prey in Yellowstone and beyond.
Hebblewhite’s research explores how wolf pack dynamics like age and experience shape their ability to hunt and impact prey populations. The wolves of Yellowstone are one of the only nonexploited wolf populations in the world, meaning they cannot be hunted or trapped by people – at least within the boundaries of the park. Hebblewhite observed how this lack of exploitation has allowed wolves in Yellowstone to develop large extended families with multiple generations.
“It’s like an extended family dinner,” Hebblewhite said. “There’s grandparents and cousins and aunts and uncles and step-siblings.”
A large pack with a range of ages gives wolves a crucial advantage. Older wolves bring their expertise to the pack and help younger, less experienced members learn essential skills. In fact, the most important factor in determining the outcome of a fight between rival wolf packs is not the number of wolves, but the presence of older individuals.
This social structure doesn’t just shape how wolves interact with each other – it also influences how they hunt.
“We’ve learned from the wolves in Yellowstone that age really matters,” Hebblewhite said. “To take down a bison, you need those older, bigger wolves.”
Though bison have begun to drive wolf dynamics more and more in recent years, elk remain the No. 1 prey species for wolves in the park, Hebblewhite said. Prior to reintroduction, there were upwards of 16,000 elk in the Northern Range alone. This population boom had devastating impacts on vegetation and other grazing ungulates like bighorn sheep.
Hebblewhite points out that reducing elk numbers was the whole purpose of reintroducing wolves, which they have more than accomplished. Elk in the Northern Range number closer to 8,000 now.
“Thirty years out, it’s impossible to conclude anything but that wolves have had an impact on elk numbers,” Hebblewhite said. “They’re a cause of elk decline, but not the only cause. Grizzly bears have almost tripled, mountain lions have recovered, and wolves returned.”
Hebblewhite and his students have dedicated years of effort to comparing the predator-prey dynamics of Yellowstone to places like Banff and Isle Royale National Park in Michigan. What they’ve found is that the complexity of the Yellowstone ecosystem is what makes it so resilient.
“Because there are multiple predators and multiple prey, the impacts of any one predator on the whole system are going to be weaker than if it were just an island with wolves and elk,” Hebblewhite said.
These insights are unique to the Yellowstone Wolf Project due to the sheer longevity of the research. Wolves are expensive to study, requiring costly equipment and highly trained personnel, meaning most wolf studies are only a couple of years long. Hebblewhite said the Yellowstone Wolf Project’s 30-year tenure makes it the world’s best study on wolf populations.
His own research builds upon a long legacy of UM scientists leading wolf research and advising management in the West.
“Since 1982, when wolves naturally recolonized northwest Montana and Professor Bob Ream here at our college started the first wolf research, we have had a strong wolf research program training students and future state biologists about wolves,” Hebblewhite said.
One of Hebblewhite’s former students, Jeremy SunderRaj, now works as a biological science technician for the Yellowstone Wolf Project – a role that puts him at the forefront of both research and public education about wolves in Yellowstone. Having been interested in wolves since seeing them in the park for the first time as a kid, SunderRaj was familiar with Hebblewhite and his work at UM before he ever stepped foot on campus. As an undergraduate in the Wildlife Biology program, he was assigned Hebblewhite as his faculty mentor.
“My first day on campus, I walked in and knocked on his door,” SunderRaj said. “He didn’t know who I was – I think he was surprised that a freshman would show up at his office –but that was the first time we met. We started working together pretty quickly after that.”
Under Hebblewhite’s guidance, SunderRaj conducted his senior thesis on the impressive visibility of wolves on the landscape, which is another feature unique to the Yellowstone population. While interning in the park during summers, he collected data on factors that make wolves more or less likely to be observed. His research, which he and Hebblewhite later published, identified the areas of the park where wolves are most visible to observers.
After graduating, SunderRaj joined the Yellowstone Wolf Project full-time, conducting research, education and monitoring on wolves and other carnivores. When not analyzing wolf kills or surveying packs from the skies, SunderRaj uses Yellowstone’s millions of annual visitors as an opportunity to increase public awareness about wolves.
“Education is one of the most important things we do with the project because we have a platform,” SunderRaj said. “We biologists are out on the roads and have the privilege to interact with the public. That gives us the opportunity to educate directly, and people get to learn straight from biologists.”
As the Yellowstone Wolf Project celebrates its 30th anniversary, Hebblewhite and SunderRaj are gearing up for a new collaboration investigating the survival rates of elk calves in the Northern Range. It’s been over 15 years since the last study of its kind, which was conducted when predators like wolves, grizzlies and mountain lions were at their peak. Before that, elk calf survival hadn’t been studied since before the reintroduction and recovery of these predators.
“Now that we’ve stabilized predators and the elk herd, we can see how this has played out for thousands of years,” SunderRaj said. “We’re excited to finally be able to answer that question for the first time in a hundred, two hundred years.”
SunderRaj is one of many students mentored by Hebblewhite who now lead wolf research, management and recovery across the West. His current and former students are heading up wolf reintroductions in Colorado and monitoring wolf movements into California, as well as furthering the legacy of the Yellowstone Wolf Project.
From Banff’s ridgelines to Yellowstone’s Lamar Valley, the wolves Hebblewhite first tracked as a young researcher have shaped the course of his career. Now the next generation of scientists he trained are bringing the lessons from Yellowstone’s wolves to wolf populations across the country, securing UM’s indelible mark on the field of wolf research.
“There’s a lot of really exciting projects coming along with the Yellowstone Wolf Project, and a lot of that is with UM so that’s pretty exciting stuff,” SunderRaj said.
