Polar bears are solitary creatures. They roam around their (increasingly less) snowy habitats, looking for food and love. Food is simple enough. But they have to sniff out love. No, literally, polar bears smell other polar bears' footprints to know if they can follow them to a suitable mate. How romantic!
Scientists have long suspected that polar bears followed more than just the footprints themselves. And a team of researchers from the San Diego Zoo and other institutions recently figured out the details. To do so, they collected scent samples from the feet of 203 wild polar bears and set up an experiment that gave polar bears in captivity the chance to sniff those scents. The research team was careful to note which polar bears were males, which were females, and which were females in their fertile period.
The experiment was pretty simple really. The research team swabbed pieces of cardboard with the scents of various wild polar bears, put the cardboard in a box near the polar bears in captivity, and watched for reactions. They specifically watched for one of three things: approaching the box, sniffing the box, and an expression called flehmen. (This is a mammalian behaviour that involves sniffing while curling the upper lip so that some of the scent goes into the mouth.)
Perhaps unsurprisingly, the scientists found that polar bears were typically twice as interested in footprint scent from polar bears of the opposite sex. Even more interestingly, though, the male polar bears were twice as interested in the scent from a females in their fertile period than those that weren't. These findings led the team to the conclusion that the bears must be reacting to a chemical difference in the footprint scent that enables polar bears to communicate basic information about sex and fertility.
That footprint-sniffing ritual is only the beginning. Eventually, the wild polar bears find their long lost lover, and then next thing you know, a little Knut lookalike is born. All mankind needs to do now is figure out how to stop destroying the bears' habitat.
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