By Erin Ross

Oregon Public Broadcasting

PORTLAND — A fatal cougar attack has reignited debates over hound hunting and cougar management in Oregon. Some think Oregon’s cougar population is growing out of control. Cougar advocates think cougars are overhunted, which research suggests can lead to an increase in problem encounters.

The Oregon Department of Fish and Wildlife estimates there are between 6,600 and 7,600 cougars in Oregon. That’s three times higher than the numbers reported Washington or Idaho. It’s slightly higher than the estimate for California: 4,000 to 6,000 cougars are thought to roam the state.

Hunting groups, ranchers and Oregonians who live in cougar country say the cougar count severely underestimates the state’s population. Conservationists argue it’s too high. Biologists and wildlife officials from other states say it’s more than just a question of numbers.

Oregon’s number is higher because it estimate includes kittens, which rarely survive to adulthood. Oregon does not count the juveniles of any other game species, like elk or bighorn sheep.

“The fact that they don’t clarify themselves every time says that they want people to assume there are 6,600 big cats running around the state,” said John Laundre, a predator ecologist at Western Oregon University.

Only adult animals can be hunted.

Derek Broman, ODFW’s state carnivore biologist, said whenever he gives a presentation, he makes it clear all ages are included in official population estimates. There’s no mention of that on the department’s cougar webpage. Only when looking deep into the cougar management plan are the adult cat estimates. A brochure specifies the population includes all ages and never offers adult numbers.

Even excluding kittens and juvenile cougars from population estimates, Oregon reports some of the highest densities of adult cougars in the country.

Washington’s research into cougar densities dates back nearly two decades and includes seven study areas. Across those areas, the state has documented consistent findings: Roughly two cougars for every 100 square kilometers, said Rich Beausoleil, the bear and cougar specialist at the Washington Department of Fish and Wildlife. He said Washington’s cougar-density numbers are consistent with what other studies — except Oregon’s — report.

Oregon Department of Fish and Wildlife’s surveys found adult densities twice that, depending on the ecosystem.

“I’ve not seen such high densities anywhere in the world,” said Rob Wielgus, former director of the Large Carnivore Conservation Lab at Washington State University.

Beausoleil has spoken to ODFW about the state’s population estimates before, and has criticized the design of Oregon’s studies, which he said will naturally overestimate regional populations.

Derek Broman said ODFW controlled for overestimation and stands by their data.

It’s not unusual for cougar surveys to arrive at different conclusions, said David Stoner, a cougar biologist at Utah State University. Cougars are hard to study because they’re hard to find.

ODFW believes these surveys confirm their statewide population estimates, which they calculate using a model. They estimate statewide density by mapping cougar deaths, and then add expected birth rates. They tweak the numbers depending on food availability in the region.

Laundre said the growth estimate used in the study is optimistic: “A model is only as good as what you put into it. I could make their model show that there were only 3,000 total animals or 10,000 total animals.”

All of this might seem like an internal debate about the best way to count cougars. Everyone agrees that at one point in the 1960s, there were only 200 or so cougars in the state, and today, there are several thousand. The cats are in no danger of going extinct.

A lot rides on accurate population estimates. Not only do these numbers tell management officials if populations are growing or shrinking, they’re used to help set hunting quotas for each region. Some scientists found that when cougars are over-hunted, problem encounters with humans and livestock increase.

Wielgus, who has left Washington for the Bend area, was one of the first to identify such a link.

“In the 20 years of research I did with WDFW, we conducted the largest study of cougars ever done anywhere. We found that heavy retaliatory killing or preventive killing actually causes increased problems,” he said.

Female cougars have small overlapping territories that seem to fluctuate with prey abundance. Male cougars have larger, non-overlapping territories that encompass multiple female ones. Only large, older males are capable of holding down these territories.

Wielgus found that those 10-year-old males were far more likely to be killed by hunters.

“And we found that when you remove an older male, you have two or three teenage males come in to take their place. And those are the ones that are responsible for most bad encounters between cougars and people, as well as the majority of livestock and pet depredations,” he said.

The movement of younger animals means it can be difficult to tell if a population is declining due to overhunting.

Wielgus is a controversial figure in predator management, in part for research indicating hunting wolves can increase attacks on livestock.

A smattering of papers have attempted to debunk his cougar research. More have supported it. One of the most recent was a massive, 30-year look at hunting and problem cougars in British Columbia.

The Washington Department of Fish and Wildlife stands by Wielgus’ research and their own: Today, they manage cougars specifically to avoid the consequences of over-hunting.

“Our management philosophy is to manage for the social stability of the animal. We want to promote territoriality,” Beausoleil said.

WDFW’s data shows that when more than 14 percent of a cougar population is harvested in a region, the population starts to skew young, territories dissolve, and problem encounters increase. To avoid this, they split the state into 49 game management units, and each unit allows 12 percent to 16 percent of cougars to be taken. When one of those units reaches that quota, it closes, and hunters can go to an adjacent unit.

At first glance, Oregon seems to be following Washington’s guidelines: On average, Oregon’s hunters take less than 14 percent of the state’s big cats each year. Unlike Washington and Montana, where there are dozens of game management units used to set cougar quotas, Oregon’s cats are divided into just six large regions, which makes it more difficult to track regional densities.

The statewide quota for 2018 is 970 human-caused deaths — 27 percent of the state’s estimated 3,500 adults. Per the cougar management plan, the quota serves as a cap, not a target. The statewide quota has never been filled. Some of the game management units regularly approach theirs.

Zone A, which includes the region where the hiker was attacked, covers the North Cascades and the coast. As of Nov. 6, humans have killed 167 of the 180 allowed cougars. ODFW estimates there were 989 cougars of all ages in Zone A in 2015. If half of those were adults, then roughly one third of adult cougars in the region were killed: Research suggests that’s a number high enough to cause conflicts with humans.

Overhunting cougars can impact cougars’ societies, too. Mark Elbroch, the director of the puma program at wildcat conservation organization Panthera, studies cougar communities. He’s found the mountain lions within one male’s territory function like a society: They interact non-aggressively and seem to share food.

“You can imagine that overhunting will have huge impacts on these social networks and organizations, on the glue that holds them together as functioning groups,” Elbroch said.

ODFW’s Derek Broman is dismissive of the “social chaos” hypothesis.

Oregon removes more moutain lions than neighboring states. In 2017, there were 462 such complaints, and 175 cougars were killed. Those numbers remain fairly stable from year to year, though they’ve risen dramatically in the Willamette Valley. About 100 cougars are killed in California each year for attacking livestock. In 2016, 46 nuisance cougars were killed in Washington.

Hunters say the best way to combat these problem cats is to increase hunting. Unless a large number of cougars are removed over a large area, more will just move in to take their place.

Biologists say it’s important to remember that the only way most people will ever interact with a cougar is through their livestock or pets.

“Cougars aren’t fearsome,” said Laundre, who has tracked and collared more than 250 cougars. “I’ve never had a cat behave aggressively.”