Habitat fragmentation, the process through which a large area is transformed into smaller more separated ones, affects all species but especially those that cover a wide range, such as cougars. This big cat is also in trouble due to its bad swimming skills, which limits its capacity to move around fragmented areas when there’s water – or so we thought.
Using a GPS tracker on its collar, researchers recorded a young male cougar swimming two-thirds of a mile from mainland Washington State to a deserted island. This finding challenges “current thinking about the extent and connectivity of the cougar range,” the researchers wrote in a press release, which could be good news for the species.
Evidence for swimming cougars, either anecdotal or scientific, has so far been very limited, leading to researchers thinking that large bodies of water acted as a barrier to their movement. However, the new study shows that cougars can swim surprisingly long distances, as seen with the feline known as M161, or Nolan, in Washington State.
A very good swimmer
Cougars living in Washington State’s Olympic Peninsula, where Nolan’s swimming abilities were spotted, face several constraints. The peninsula is not only surrounded by water, but also by the Interstate Highway 5 (I-5) corridor that runs south from Seattle to Portland, Oregon, cutting off access to many species on the peninsula.
A team of researchers, Native American tribes and land trusts have long been working to protect the cougars in the area under the so-called Olympic Cougar Project. The initiative seeks to identify and protect wildlife corridors and promote research, as with this new study, which has tracked the movements of Nolan and his mother since 2020.
Nolan, who initially tagged along with his mother, set out on his own in April of that year. He first spent several months on land and then went for a swim from the eastern edge of the peninsula to Puget Sound’s Squaxin Island – covering 1.1 kilometers. This suggests many of the islands in the peninsula could be accessible to the cougars.
There is a total of 6,153 islands in the study area, of which 3,808 could be accessible to cougars with one or more 1.1-kilometer swims, the researchers found. They noted the presence of cougars on 18 of these islands. Surprisingly, they also confirmed cougar sightings on four islands that would have required swims closer to two kilometers.
The findings will help the conservation of cougars and many other species, they said. The large cats are an umbrella species, which means protecting them helps the other animals they share the landscape with. Jim Williams, a cougar biologist not related to the study, told National Geographic the next step is to set up corridors to protect them.
The study was published in the journal Northwestern Naturalist.
