Research shows that cougars on the Olympic Peninsula are isolated from other populations in Washington state, which could spell trouble for the big cats long-term.
WASHINGTON, USA — A study recently published by the Washington Department of Fish and Wildlife (WDFW) is shedding light on how cougars move throughout the state and how cougars on the Olympic Peninsula may be more cut off from other populations, which could spell trouble for the big cats long-term.
An analysis of DNA taken from over 1,900 cougar tissue samples gathered over the last 16 years revealed several genetically distinct populations of cougars in different regions of the state. The analysis showed those populations intermixing, meaning they were able to breed and exchange genetics with different groups.
However, that was not the case for cougars on the Olympic peninsula.
“You would see that cougars from the Cascade Range are also making their way over to the Selkirk Mountains and that, you know, cougars in the Blue Mountains are exchanging with cougars in Oregon and Idaho, and you know, maybe cougars in southwest Washington are intermixing with the southern Cascades,” said Richard Beausoleil, WDFW Wildlife Biologist and co-author of the study. “It appeared from the genetic analysis is that animals were occasionally able to leave (the Olympic Peninsula) but we weren’t seeing a lot of exchange coming from off the peninsula back onto the peninsula.”
WDFW Wildlife biologist Lindsay Welfelt, geneticists Katherine Zeller and Claudia Wultsch, and Erin Landguth with the University of Montana co-authored the study.
With the data gathered by WDFW and the DNA analyzed by Zeller and Wultsch, the researchers assigned each distinct cougar population a color, which would allow them to map where cougars from different populations were mingling. The data would also determine which groups did not appear to be connecting with the other groups at all. That gave researchers an idea of how easy or difficult it is for cougars to move around based on where they’re located in the state.
“When we look at those patterns and the genetics throughout the entire population, then we can start associating that with different habitat variables that might be limiting that gene flow, or creating more resistance to movement,” Welfelt said. “So that’s what this paper really did is try to identify those habitat features that are limiting movement, and then that helps us identify areas where we might need to increase connectivity where it’s really limited or maintain connectivity where it’s really high.”
Male cougars in particular are known to have extremely wide home ranges and can disperse up to 120 miles from where they were born. Based on the lack of genetic diversity seen on the Olympic Peninsula, it’s appearing to researchers that there are barriers preventing males from other cougar populations from mingling with those on the peninsula, which poses a challenge to the survival of the group.
If distinct groups of animals become isolated from other groups, the population can become less genetically diverse, which could make them less resilient to environmental challenges over time.
“The lower genetic diversity becomes, in the beginning, the animal will look the same, but it will be less able to adapt, and it will have less resistance to change,” said Dr. Mark Elbroch with the Olympic Cougar Project. “So let’s say there’s a fire or a disease outbreak or anything that kind of disturbs the ecosystem, and the animal’s ability to adapt and overcome changes in its environment is all built within its genetic code. The less genetic diversity, you can think of it as less options that animal has to adapt… they are just more likely to be impacted by sudden change.”
The Olympic Cougar Project is co-led by Panthera, a nonprofit dedicated to the conservation of wild cats, and the Lower Elwha Klallam Tribe in collaboration with six other local Native American tribes. The Lower Elwha Klallam Tribe received funding to conduct a small-scale study on cougars in 2017. The Tribe contacted Elbroch and asked him to teach them how to study and catch the big cats. After research came out showing cougars on the Olympic Peninsula are more genetically isolated than other groups in Washington state, the group turned their focus toward conservation.
The Olympic Cougar Project has been tracking cougars with GPS collars to see how they move throughout the region. Their readings show there are two major features that are limiting the way cougars move: Parts of Olympic National Park that are mostly rock and ice, and Interstate 5.
“The I-5 corridor is just essentially a big wall and cats aren’t crossing it,” Elbroch said.
With the Columbia River to the south and the Pacific Ocean to the north and west, Cougars on the Olympic Peninsula have very few options when it comes to leaving the area, and as research suggests, it’s proving difficult for cougars from elsewhere in the state to travel there.
“If (male cougars are) faced with a choice of going across I-5 onto the peninsula or maybe joining up with the south Cascades, they’re going to take the latter,” Beausoleil said.
Another major concern is the growth and development in the Puget Sound region, which is expected to double in population by 2050. Researchers said now is the time to begin implementing solutions linking cougar populations in Washington state to avoid major consequences for the creatures in the future .
Welfelt said that while the Olympic Peninsula cougar population is okay for right now, “we’re moving toward someplace that we don’t want to be.”
“If there’s some interest in preserving some of those habitat corridors that currently exist, now would be the time to start thinking about it,” Beausoleil said.
Beausoleil, Welfelt and Elbroch pointed to wildlife overcrossings like those seen on I-90 as a potential solution to linking cougar populations on both sides of I-5. Although that work can take years, some agencies are already looking at solutions for animals isolated by the interstate.
For example, the Washington Wildlife Habitat Connectivity Working Group brings together representatives from the Washington State Department of Transportation, WDFW, the Washington Department of Natural Resources, the Woodland Park Zoo and the University of Washington, among other organizations to identify opportunities for connecting wildlife in the state.
“This genetic work has come out at the perfect time because here we are all working on this very subject and it just provides evidence of the importance of the work that we’re doing and how important it is to move quickly because you know these landscapes are just continuing to fracture,” Elbroch said. “People are buying up whatever’s left to buy and if we want to protect those last few linkages across I-5 which still would need bridges and underpasses, we better get on it, because ten years from now they’re gone.”