Under pressure: Study analyzes how elk manage threats from predators, humans

Elk in northeastern Washington have a lot to deal with.

Beyond the basic needs of food and water, the animals have to manage a complex network of competing predatory threats – from carnivores like wolves and cougars and from humans, who hunt elk in the fall and occasionally hit them with their cars.

“They’re kind of between a rock and a hard place between trying to manage risk from predators and humans,” said Taylor Ganz, a research scientist at the University of Washington.

Ganz and a handful of other researchers spent four years trying to figure out just how the elk manage those risks. The result is a paper published recently in the journal Ecology, which found the large ungulates move between habitat types in response to whichever threat is most pressing.

It also found that humans play a dual role in shaping the lives of elk – as predator and protector.

While hunting and vehicle collisions were the top causes of mortality in the study, and it also found that elk would spend nights in habitat that was closer to civilization, possibly as a way to protect themselves from predators that are less keen on being around people.

“They’re using us and those areas as a shield against predators that wouldn’t want to be close to humans,” said Melia DeVivo, a Washington Department of Fish and Wildlife biologist and co-author of the study.

The research is the latest to come out of Washington’s predator-prey project, a collaboration between WDFW and the University of Washington to study the relationship between deer and elk and their predators, particularly as wolves continue recolonizing the state.

The project began in 2016 and involves research in Okanogan, Stevens and Pend Oreille counties. It has produced a treasure trove of data on predators and the animals they hunt, including published papers on wolf-cougar interactions, how mule deer respond to predator activity and the methods used for investigating wildlife deaths.

The study looked at a portion of the Selkirk elk herd in Stevens and Pend Oreille counties. Researchers collared 63 adult female elk and 30 calves in Stevens and Pend Oreille counties from 2017 to 2021. They also collared 42 cougars and 16 wolves.

Black bears were not used in the study. Ganz said that’s because elk are generally vulnerable to black bears only as newborns, and because calf survival rates were high, they determined that black bears aren’t influencing the population.

Using the GPS data from the collars, the researchers analyzed where elk went in relation to the presence of wolves, cougars and people.

They found that elk do their best to avoid all of the predators, but their responses varied from day to night and from season to season.

During summer and fall, elk avoided cougars at night, but had “a weaker response” to the big cats during the day.

They avoided wolves in daylight and in the dark, but there were differences in the elk’s decisions between the summer and the fall.

They steered clear of areas with a “relatively high human footprint” during the day, but settled into those areas at night. It’s not that the elk are retreating to downtown Chewelah or Colville to hide out, Ganz said, but that they’re choosing rural habitat that’s closer to people – maybe an alfalfa field or a cow pasture – over remote, forested areas.

“In the daytime, elk were really strongly avoiding human impacted areas,” Ganz said. “But at night, they preferred those.”

The presence of humans is part of what made the research somewhat unique – much of the other research on wolf-elk interactions has come from Yellowstone National Park, where the two species have 2.2 million acres to roam without much in the way of human development.

Some of the elk’s behaviors ran counter to those observed in protected areas like Yellowstone. For example, the study says elk had a stronger response to wolves than cougars, despite the density of cougars being much higher than that of wolves. They also didn’t consistently avoid open habitats – like meadows – where wolves are known to be effective hunters.

That suggests that elk act differently in areas more heavily used by people, and that people play a major role in shaping the animals’ decisions.

“The reality is we play a huge part in these populations and how they can survive and thrive,” DeVivo said.

Part of that role is as a direct predator. Of the 63 adult elk that were collared, 14 died. Six were killed by hunters, and two others died after being wounded by hunters. Three were hit by cars, and the remaining three either died of disease or an unknown cause.

People also mess with the elk’s habitat through development, by building houses and roads and reconfiguring the landscape the elk occupy. That wasn’t part of this study, but it’s another pressure the animals face. Drought and disease can cause problems for the elk, too.

Still, despite all the pressures, the elk herd the study focused on appears to be doing well, DeVivo said.

“This particular population of elk seems to be thriving actually in northeast Washington,” she said.

She added that the finding that humans were the main killers of elk in the study is helpful for wildlife managers. If there’s a crash or an abrupt change in their numbers in the future, WDFW can make changes to hunting seasons or take other steps to limit the human impact.

For now, though, it seems the elk are able to manage.

“The reality is they do a pretty good job of balancing those risks from both nonhuman predators as well as humans,” DeVivo said.