To reach an uninhabited island, this mountain lion did ‘something totally unexpected’

These cats can swim long distances and hop between islands more commonly that we thought, which has big implications for their conservation.

By Douglas Main
Published 27 Feb 2023, 13:18 GMT
A mountain lion leaps across a forest stream. These animals avoid water at times, but can ...
A mountain lion leaps across a forest stream. These animals avoid water at times, but can also swim long distances in certain circumstances.
Photograph by JIM AND JAMIE DUTCHER, NatGeo Image Collection

Mountain lions are not commonly thought of as animals that swim well—or are even capable of swimming long distances. But at least for one adventurous cat, that couldn’t be farther from the truth.

A new study recorded a young male cougar paddling two-thirds of a mile from the mainland of Washington State to an uninhabited island in Puget Sound. The GPS-collared feline known as M161, or Nolan, took a winding path through the outskirts of Olympia, and along the coast, before taking to the sea.

That got researchers wondering how many islands might be habitable by mountain lions. If the animals can regularly swim this far, then they can likely inhabit more than half of the area’s 6,513 islands, scientists determined.

They also combed through historical records and found evidence of mountain lions inhabiting an additional four islands outside of the range of this youngster’s swim, all of over a mile from shore or the nearest island. This suggests the animals can swim even farther at times, perhaps close to a mile and a quarter. Young male mountain lions often undertake difficult and long journeys in search of new territory, as was the case for Nolan.

“We are redefining the mountain lion in our minds as an animal that can swim and is willing to swim,” says study co-author Mark Elbroch, who leads the puma program for Panthera, the global wildcat conservation organisation. The paper was published in the journal Northwestern Naturalist.

The findings were made as part of the Olympic Cougar Project, a broad coalition of researchers, Native American tribes, land trusts, and others committed to mountain lion conservation and research, as well as identifying and protecting wildlife corridors.

Interstate 5, a busy thoroughfare that runs south from Seattle to Portland, Oregon, is cutting off access for the state’s cougars and many other species to the Olympic Peninsula, a wide expanse of forested habitat that’s surrounded on three sides by water.

“I-5 is killing us,” Elbroch says. “It’s killing the peninsula—we need to address this immediately.” There are two spots where wildlife passages could be built, but time is running out to protect these corridors as development and sprawl continue, he says.

Setting out alone—and a sad end

Nolan, who scientists tagged along with his mother in January 2020, set out on his own in April of that year. He bounced around a bit, finding his way into several towns north of Olympia. Researchers feared he might get himself into trouble, as such young and still-unexperienced cats “are trying to safely navigate a landscape without knowing what’s around the corner,” Elbroch says.

Then, between 2 a.m. and 6 a.m. on July 14, he took a swim to Squaxin Island, an uninhabited parcel of land in Puget Sound owned by the Squaxin Island Tribe. Sadly, Nolan was shot two weeks later during a legal hunt.

A swimming cougar (Felis concolor) in British Columbia. Mountain lions may be able to swim a mile or more in certain circumstances.
Photograph by Tim Melling

For this reason, islanders in cougar habitat shouldn’t leave livestock unattended, says Rich Beausoleil, a biologist with the Washington Department of Fish and Wildlife.

The findings were “not terribly surprising to me, but still very interesting and important… We shouldn’t always see water as a barrier to movement to any large carnivore,” Beausoleil says.

Taking to the water

Mountain lions, which have the biggest range of any wildcat, from Canada to Chile, regularly cross small and moderate-size rivers.

In Brazil’s Pantanal, where they’re called pumas, the cats also regularly swim in the vast wetland during the wet season. In 2010, Elbroch and colleagues documented a tagged puma repeatedly swimming across a large lake in Chilean Patagonia to eat domestic sheep on an island, swimming as far as 0.6 miles at a time.

As for swimming, “they probably don’t mind it as much as we think they do,” says Dave Onorato, a researcher with the Florida Fish and Wildlife Conservation Commission who wasn’t involved in this study.

Even still, for decades, Florida panthers—federally recognised as a subspecies of mountain lion—were rarely seen north of the Caloosahatchee, a waterway stretching from Lake Okeechobee to the Gulf Coast once considered a potential barrier to dispersal. But in 2016, a female was spotted north of the river from the first time in generations, suggesting she swam across the waterway, in a bit of good news for the panther.

Amazing adaptability

Since mountain lion numbers are much lower than they once were, and the animals avoid people, behaviours such as swimming remain under-appreciated and anecdotal, experts say.

National Geographic Explorer Audra Huffmeyer, who studies cougars in the Los Angeles area and beyond, agrees. While she wasn’t surprised that cougars can island-hop in the Salish Sea, “the distances covered are pretty incredible… the capacity of large felids to adapt to extreme habitats is pretty amazing.”

Nolan’s journey and all the data produced by Olympic Cougar Project will help land managers understand where mountain lions travel, and help identify corridors that need to be protected, says Jim Williams, a cougar biologist at the Heart of the Rockies Initiative, a conservation group.

The Olympic Peninsula certainly needs such guidance and protection, as its cougars have the lowest genetic diversity of any in the state, records show. The cats are also an umbrella species, and protecting these animals could help other animals they share the landscape with, Williams adds.

To Elbroch, Nolan’s journey represents “the ingenuity of nature—finding a way around an insurmountable obstacle.”


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