Newer science revealing secretive Yellowstone cougarsSource: Billings Gazette
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Through DNA analysis of scat and hair, along with photographs and specially equipped GPS collars, researchers in Yellowstone National Park are acquiring new information about the Northern Region’s secretive cougars.
“Because cats aren’t seen or heard much, they’re kind of out of sight, out of mind,” said Dan Stahler, Cougar Project manager.
“We’re trying to change the dialogue and get the public to understand this is a multi-predator ecosystem,” he added. “There’s another top predator that also plays an important role here.”
The work builds on a 1998 through 2005 study by biologist Toni Ruth that documented changes in cougar populations following wolf reintroduction. Ruth is writing a book on her findings and research. The first cougar study in Yellowstone began in 1987, but there was an eight-year gap between the end of Ruth’s project and the latest study.
Ask someone to name Yellowstone’s top predators, and grizzly bears and wolves are more likely to be mentioned than mountain lions. Yet Stahler’s study, along with the previous work on cougars, shows that a fairly stable population seems to roam the rugged region between the Lamar Valley and Gardiner known as the Black Canyon of the Yellowstone. Elevations in the area range from 5,300 to 9,500 feet.
“That suggests that Yellowstone serves as a core area for cats,” Stahler said, and that the animals migrate from the park to find new territories in surrounding landscapes.
Cougar estimates in the study area have varied from about 15 to 42, a count that includes subadults and kittens.
It’s a study area that covers steep, rocky, forested slopes along the Yellowstone River where year-round elk populations — along with the occasional bighorn sheep, marmot, porcupine and pronghorn — provide enough sustenance to maintain a steady cougar population.
Although elk numbers prior to wolf reintroduction in 1995 hit about 19,000, they have since plummeted to what has become a new normal of about 4,800. Surprisingly, although their main prey source has been depleted, cougar numbers seem to have stayed about the same, Stahler said.
Since 2014 researchers on the Cougar Project have spent January through March tracking the animals through snow, although the winter of 2015 proved challenging with little snowfall.
“It’s good old-school field biology, and eliminates the need for hands-on radio collaring,” Stahler said, which was more common in previous studies and is more invasive and hands-on.
By tracking the animals researchers are able to find shed or scraped off hair, as well as scat, that is collected and sent to a Missoula lab for DNA analysis.
“A single hair with a follicle is enough,” Stahler said.
The lab work can identify unique individuals as well as related cats. Results from 2014 and 2015 have identified 20 unique individuals, which Stahler called the absolute minimum population. A more definitive current population will be mathematically modeled following this year’s field research to come up with abundance, density and growth in cougar populations.
The DNA paints just part of the Yellowstone cougar picture. The crew is also attempting to attach four GPS collars to gain further insight into the big cats, as well as compare their hunting strategies to similarly collared wolves. From that information Stahler will compare how often cougars and wolves kill, seasonal differences in movements and their relationship to prey distribution in deep snow.
The collars are equipped with accelerometers, which Stahler compared to a human fitbit, a wristwatch-like device that can measure everything from a human’s heart rate to their speed and distance. The accelerometers will measure activity level and body position across different seasons, habitats and levels of hunting success.
Although cougars have claws that give them an advantage over wolves for grasping and taking down their prey — and they are as muscle-laden as body builders — they are a short-range hunter, using quick bursts of speed to capture their prey.
“We do see scenes where there’s been quite a battle,” Stahler said. “They’ve fallen off cliffs attacking bighorn sheep.”
Female cougars will make a kill on average about once a week, compared to once every 11 to 13 days for males, Stahler said.
A pack of wolves, on the other hand, will run long distances before making a kill about every two to three days, but there are more mouths to feed in a pack. Wolves and bears will also chase off cougars to take over their kills, evidence of what Stahler calls Yellowstone’s “multi-carnivore system.”
Camera traps are the final bit of technological wizardry the Cougar Project is using with help from National Geographic photographers. The remotely activated cameras are being set up to document the elusive cat’s behavior, since they are so rarely seen in the wild.
So far the cameras have captured photos and video of family groups interacting, scent marking and have shown which cats are in a certain area. The most vivid example of this was when a male cougar showed up on camera with what appeared to be battle scars only days after another male cougar was killed in a territorial fight.
Taken all together the less invasive research methods are painting a more detailed picture of one of the least-seen predators in America’s first national park, while also taking into account their interaction and effect on other predators like wolves and bears to look at “community dynamics,” as Stahler called it.
“Our effort is to try to change the dialogue and get the public to understand this is a multi-predator ecosystem,” Stahler said.
“And what we’re seeing in Yellowstone is a pretty healthy landscape for cats.”