Fat Polar Bears Live Longer

Polar bears may have an uphill battle in the fight against global warming, but it looks like the bears with more fat cells have the best chance of survival. A team headed by the University of Alberta’s Seth Cherry studied the migration patterns of the world’s largest land predator by tracking the animals with radio collars as far back as 1991.

“Ultimately, for polar bears, it’s survival of the fattest,” he said about the team’s results, which were published last week in Journal of Animal Ecology.

The movement of the bears was tracked between 1991–1997 and 2004–2009, using special collars that could send the telemetry data to satellites. The more modern collars could send back GPS coordinates every four hours, but the 1990s-era collars only sent back the data every two to 10 days.

Only female bears were collared, since the males have thick necks and wouldn’t fit into the devices. Is it just me, or can we all agree that handling adult male polar bears might also be even more risky than dealing with a grumpy female who has just emerged from what the scientists called the maternity den?

Polar bears mainly feed on seals, which they capture in the water. However, they are not marine mammals themselves, and they can’t swim indefinitely. Once all sea ice melts, they have no choice but to migrate back to land, where they must often survive for a very long time without eating.

The National Wildlife Federation statement doesn’t mince words: “The bears were the first vertebrate species to be listed by the U.S. Endangered Species Act as threatened by extinction primarily because of global warming.” Their hunting habitat disappears for longer and longer periods during the arctic summer.

The Canadian migration study has confirmed that theory. The polar bears are going to land earlier and leaving later. Earlier research has also discovered that the desperate bears may be increasingly likely to mate with a member of a different species.

Only the fattest can survive the enforced period of prolonged fasting. Maybe we need to bring the obesity epidemic to the polar bears.

[swimming polar bear photo courtesy “John” at Wikipedia Commons]