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Scientists piece together the wanderings of a young male cat

August 2, 2011

A young male cougar killed in Connecticut — where no wild populations have lived for more than a century — arrived in the state after a nearly 2,000-mile journey that began in the Black Hills of South Dakota. Scientists used DNA fingerprinting to identify his home population, and pieced together his probable route using hair and fecal samples, paw prints and images from trail cameras

The tale starts with an unidentified body found on the roadside. Hit by a car in the wee hours of the morning, investigators puzzled over where it had come from and how it had reached its asphalt resting place.

But this wasn’t a human murder mystery: The victim was a young cougar, struck down on the Wilbur Cross Parkway in Milford, Conn., on June 11. The incident shocked a state where drivers are accustomed to seeing white-tailed deer dash in front of their windshields, not 140-pound predatory cats. On July 26, after working for weeks to piece together the cougar’s story, scientists delivered a surprising saga of the cat’s 2,000-mile journey from the Black Hills of South Dakota to the green lawns of southern New England.

When the young male was killed, investigators initially thought the cat might have been a captive animal — no wild cougars have been documented in Connecticut since the late 1800s.

But a necropsy suggested otherwise. “It was not declawed, it was not neutered, it wasn’t overweight,” says wildlife biologist Paul Rego of the Connecticut Department of Energy and Environmental Protection, who coordinated the state’s investigation. There was no microchip under the animal’s skin — just embedded porcupine quills.

Perplexed, scientists sent a chunk of muscle to the U.S. Forest Service’s Wildlife Genetics Laboratory in Missoula, Mont., hoping genetics could help determine the cat’s home range.

Over the last decade, the lab has built an extensive genetics database comprising 50 different wildlife species, says lab director Michael Schwartz. Scientists use the information mostly to study how land management affects population breeding patterns and the dispersion of animals within their current range, which are crucial for preventing inbreeding and reproductive isolation.

“But we do a lot of this kind of work,” Schwartz says. “Every once in awhile a cougar decides it’s going to show up in an area where there isn’t a wild population.”

Schwartz and his team compared DNA from the Connecticut cat’s muscle to the roughly 800 cougar samples in the database, using DNA fingerprinting techniques similar to those U.S. officials likely used to identify Osama Bin Laden’s body. They looked at 20 DNA microsatellites — areas with repeated genetic elements of varying length — as well as portions of maternally inherited DNA from the mitochondrial genome. The mitochondrial DNA confirmed that the cat came from North America and was not a South American import — captive animals usually are. The microsatellite data matched the genetic profile of the Black Hills cougar population, with 99.8 percent certainty.

Although the western United States is home to an estimated 30,000 cougars, the Black Hills cats number between just 200 and 250, says wildlife biologist Jonathan Jenks of South Dakota State University in Brookings, who has studied the population since it began recolonizing the area in the late 1990s. Jenks and his team have put radio collars on an estimated 300 individuals and followed the cougars as they travel to places like Oklahoma and Saskatchewan. “About 90 percent of the sub-adult males leave the Black Hills,” Jenks says. “And they travel extensively, that’s for sure. Especially the males. But I’m surprised this one made it so far.”

Schwartz says he was stunned to learn the animal’s genetic profile was already in the lab’s database. “We didn’t believe it at first,” Schwartz said. “We actually had our techs rerun the sample, just to be sure.”

It turned out the older samples — hair and fecal matter — had been collected more than a year earlier by biologists tracking the Connecticut-bound cougar across Wisconsin. First spotted in Chaplain, Minn., in December 2009, biologists tracked him as he zig-zagged through Wisconsin, leaving behind a trail of paw prints, hair and poop.

Even in Wisconsin — with its bears and wolves — cougars are unexpected visitors, says mammalian ecologist Adrian Wydeven of the Wisconsin Department of Natural Resources in Park Falls.

There have been only four confirmed cougars in that state since 2008, so when the traveling cougar appeared, Wydeven and his team kept a watchful eye on his movements. From December 2009 through late spring 2010 they haunted the cat’s trail, collecting samples and sending them to the lab. In December, a trail camera captured a cougar prowling through the evening snow near an area where hair had been sampled earlier, providing scientists with a glimpse of the cat.

Then, after another trailside portrait in May 2010, the cat disappeared.

Cougar in the badlands in North Dakota

The next time he appeared was more than a year later and a half-continent away, just a few miles from the Connecticut shore. Scientists don’t know much about the cat’s journey between Wisconsin and Connecticut, but wildlife biologist Clayton Nielsen of Southern Illinois University in Carbondale speculates the cat probably crossed Michigan’s Upper Peninsula, then wound his way down through New York. “There’s no real way of knowing,” he says. “But going south through Illinois, Indiana, Ohio — that’s very poor habitat, with a high likelihood that people would see the animal.”

Nielsen, who is studying cougars in the Midwest, says while roaming young males are increasing in the area, there are still no known breeding populations east of the Black Hills, except for an endangered group of less than 100 in and around the Florida Everglades. Scientists hypothesize that the Connecticut cat was wandering in search of food and a mate — but since he didn’t find a mate, he kept on moving. Female cougars don’t travel nearly as far as males, which limits the establishment of new breeding populations. But, Nielsen hypothesizes, if a few females made similar journeys, it’s plausible that a cougar population could re-establish itself farther east.

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