Polar Bear Paws Lead the Way to Potential Mates

Polar bears have smelly feet, scientists have discovered, and the pungent marks their paws leave behind while trudging through the Arctic snow help lead the way to potential mates, according to new research.

And no, it's not because their large meat hooks are dirty or unwashed, but rather because their tracks leave behind chemical trails wherever they walk due to scent-producing glands in their feet. Scientists at the San Diego Zoo Institute for Conservation Research also found that polar bear paws release DNA and traces of urine.

And for these nomads who live a solitary existence, they need all the clues they can get to smell their way to a potential mate.

For a new study, published in the Journal of Zoology, researchers wanted to investigate the role of this chemical communication. The team included Megan Owen, of the Institute for Conservation Research at San Diego Zoo, and colleagues from Polar Bears International and the US Geological Survey. Together they spent five years sampling pedal scents left behind by 203 wild polar bears living around either the southern Beaufort Sea or the Chukchi Sea in the Arctic Ocean.

The scientists then offered these scents to 10 adult male polar bears and 16 adult females - mostly wild-born - living in 10 different zoos across the United States.

It turns out that especially in the springtime, males have to fight against other males to mate with females "with location of mates as the first phase of competition and direct male-male contest competitions as the second phase," the researchers wrote. That's because females were most attracted to scents left by wild bears in the spring, and to bears of the opposite sex. Males were especially interested in female bears that were in heat.

"These results suggest that pedal scent, regardless of origin, conveys information to conspecifics that may facilitate social and reproductive behavior, and that chemical communication in this species has been adaptively shaped by environmental constraints of its habitat," the team said.

However, conservationists worry that as the Arctic warms due to climate change, it could threaten this process and further endanger the species. If the sea ice continues to break apart, it could make it more difficult to leave behind scent trails, and for the bears to find each other.