Scientists unlock mysteries of the cougar diet
Study of scat finds reclusive cat prefers to dine on sea lions, seals instead of just deer
When researchers in Pacific Rim National Park Reserve started collecting cougar scat samples, they expected the analysis to show a diet primarily of black- tailed deer.
But they were taken aback to learn that deer comprised only a quarter of the cougars’ diet in the park, and that an unlikely smattering of other animals — notably harbour seals and even sea lions — comprised the remainder.
“What’s surprising to me is that deer is not the primary prey species,” Danielle Thompson, park resource management specialist, said in an interview. “It’s a secondary prey item and raccoons are actually No. 1.”
The research is considered the first scientific documentation of cougars exploiting marine mammals in North America.
“This is really interesting; imagine a cougar stalking its way across a barnacle-infested reef,” responded Chris Darimont, a Victoria- based researcher who has extensively studied how wolves on the B. C. coast exploit marine life, including spawning salmon.
“I know of no other account of cougars eating a marine mammal. But I’m not completely shocked. There is some pretty delicious seafood out there. Seals are loaded with calories, fat and protein. They’re big prizes, and, compared with deer, a little safer to hunt.”
An analysis of 29 cougar scat samples taken from Long Beach to the West Coast Trail showed the following diet: raccoon, 28 per cent; harbour seal, 24 per cent; black- tailed deer, 24 per cent; river otter, 10 per cent; sea lion, seven per cent; mink, four per cent; unknown; three per cent.
Prey items were identified in the field by carcass examination or through scat analysis by way of guard hair classification and bone- fragment identification, Thompson said.
A minority of cougar scats were verified through DNA testing while others were identified through means such as sightings, tracks, remotely triggered cameras, and location.
Wolves tend to deposit their scat in conspicuous locations at the confluence of trails or raised ground features, Thompson said, whereas cougars are less conspicuous and often bury their scat with forest debris. Wolves also generally have twisty scat, while cougar scat is more segmented with blunt ends.
“Cougar scat is difficult to find,” she added. “They are solitary predators, not like a pack of wolves.”
Although the sample size is small and could distort the picture of what’s happening, Darimont noted, the study nonetheless confirms that cougars can and do exploit marine life and emphasizes the vital link between species that inhabit the land and ocean.
“Imagine the broader context, and what a catastrophic oil spill would mean for marine life up and down the coast,” he warned. “The terrestrial ecosystem is so coupled to the marine ecosystem.”
A study of 113 wolf scat samples in the park showed a similar range of prey species, evidence of competition between the two predators.
One theory, Thompson said, is that younger cougars lacking the skills to take deer may be exploiting easier, smaller prey. Some cougars may also defer deer hunting to the coast’s dominant wolf packs.
Where cougars successfully catch a seal or sea lion, she added, it likely involves young or sick and injured individuals on the shoreline. While cougars are good swimmers, they are not thought to chase through the surf to capture marine life.
Thompson said the research emphasizes the need for park visitors to be aware of the presence of wolves and cougars and how to respond should they encounter one.
An 18- month- old boy was injured in a cougar attack last August at Swim Beach, in the Kennedy Lake day- use area of the national park, about 16 kilometres east of Ucluelet.
Parks Canada recommends that people encountering a wolf or cougar should pick up small children and gather in a group. Do not run or crouch down. Make and maintain eye contact. Wave your arms and shout, do what you can to appear larger and scare the animal away. Use a noisemaker or throw rocks. Fight back if attacked, hitting the animal in the eyes or nose.
Researchers in Pacifi c Rim National Park Reserve have found cougars’ favourite food is raccoon.