for National Geographic News
To follow the movements of cougars in remote areas of western North America, a team of biologists has found a different kind of tracking device: a virus.
Borrowing a method used to study human demographics, biologist Roman Biek and his colleagues took samples from 352 cougars in the Rocky Mountain region of the United States and Canada.
The researchers analyzed the samples for strains of feline immunodeficiency virus (FIV), which is common in big cats and does not appear to affect them.
The analysis identified eight major FIV strains carried by cougars in Montana, Wyoming, British Columbia, and Alberta.
These unique strains allowed the scientists to track where the cats had been and at approximately what time.
One strain spread over a distance of 620 miles (1,000 kilometers), while others remained relatively isolated.
Results of the team's research appear in the current issue of the journal Science.
"This is a tool to determine over what spatial scales [the cougars] have moved recently," said Biek, a professor of biology at Emory University in Atlanta, Georgia.
"If you find a virus that is widely distributed, then we know the cougars are getting it around."
Follow the Bug
Cougar (Wallpaper photo: "Mountain Lion") populations suffered rapid decline in the early 20th century, largely due to hunting. The cats that survived were both few and geographically isolated.
Because viruses evolve quickly, Biek explained, the strains of FIV carried by the cats became distinct across regions. Today a cougar from Yellowstone, for example, carries a slightly different FIV strain than a cougar from the Yukon.
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