Yellowstone National Park Plans Elk Population Study

By Dana Kobilinsky

Yellowstone Elk
Female elk stand on top of a high ridge in Yellowstone avoiding cougars, wolves and bears. A recent survey of elk in Yellowstone showed an increase in population, but senior wildlife biologist at Yellowstone National Park Doug Smith said they might have just had a better count this winter.
Image Credit: David Doan via Flickr

Yellowstone National Park is teaming up with Utah State University to conduct a study that will help determine why the northern Yellowstone elk herd has declined 60 to 70 percent since 1990, according to Doug Smith, senior biologist at the park. “We are really working hard to understand the elk population in a predator rich environment.”

Researchers will use the same radio-collared elk that they survey annually to determine if certain predators are to blame for the decline, Smith said. He said that while there are very few long-term studies on elk, Yellowstone’s vision is long-term.

The study will begin next winter and will help determine how accurate the annual elk survey is, according to Smith. The group will monitor trends in the Yellowstone elk population and evaluate other contributing factors including predation, hunting and environmental conditions. After collecting this long-term data, researchers will assess the numbers.

Yellowstone National Park researchers also are teaming up with Montana Fish, Wildlife and Parks, the U.S. Geological Survey and the state of Montana next year to collect data and conduct a more accurate elk population survey after a somewhat surprising increase in elk in this past winter survey.

Smith said that in the 1980s, an elk sightability model — developed to account for variation in detection of elk — was created that showed the average number of missed elks is 30 percent when they are counted. “What we report is an undercount, but each year we don’t know by how much,” he said. “We are redoing the study because the factors that affect sightability have changed since the 1980s.”

In fact, when biologists with Yellowstone National Park surveyed its elk herd population this winter, they were surprised to see a 24 percent population increase. On the surface it seemed like the once-struggling elk population was making a comeback, but, according Smith, it could just be that the survey count was better this year. “It appears the earlier we count elk in the winter, the better the elk distribution is,” Smith said. “Counting earlier in the winter is better than counting later.”

In the 1990s, the Yellowstone elk population prospered, reaching about 20,000 individuals. With the reintroduction of grey wolves in the park, however, the elk population has fallen over the years. “Wolves declined in 2008, and they declined 60 to 70 percent in the area where we do the elk count,” Smith said. “Since then, their numbers have been pretty stable at the lower numbers since 2008.” Other factors such as heavy elk hunting, harsh winters and impacts from other predators such as bears and coyotes has led to a further decline in elk populations.

This winter, though, the survey determined that there are 4,844 elk in Yellowstone, about 1,000 more than in 2013, and the largest population since 2010. While the news is promising, Smith and other biologists are working to determine whether that represents an actual increase in numbers or if other factors such as an earlier count could be at play. If there was, in fact, an increase in elk population, it would be due to a higher survival rate for newborn calves, Smith said.

Aside from the increased number of calves, there has also been an elimination of elk hunting that might have helped the population thrive. State wildlife officials eliminated a late-season elk hunt in 2011 in Gardiner that had previously issued permits for more than 1,000 elk a year.

“Predators and prey are going to oscillate at a stable equilibrium for years to come,” Smith said. “The main takeaway is that we need to improve the accuracy of our counts.”

Dana KobilinskyDana Kobilinsky is associate editor at The Wildlife Society. Contact her at dkobilinsky@wildlife.org with any questions or comments about her article. You can follow her on Twitter at @DanaKobi.

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