How pandas use their heads as a kind of extra limb for climbing

AUSTIN, Texas — Pandas really use their heads to climb.

As the pudgy, short-legged bear climbs, it presses its head briefly against the tree trunk again and again, physicist Andrew Schulz said January 4 at the annual meeting of the Society for Integrative and Comparative Biology. The head serves as a make-do extra paw, first pressed against one side of the tree and then against the other. This extra pressure helps the bear hold on as it releases and raises an actual paw. Schulz knows of similar behavior only in newborn kangaroos, which use their heads to help haul themselves to their mother’s pouch for the first time.

Head moves make sense for panda proportions, said Schulz, speaking for a research collaboration between his university, Georgia Tech in Atlanta, and China’s Chengdu Research Base of Giant Panda Breeding. Pandas have the shortest leg-to-body ratio among the world’s eight living bear species. “I like to call them Corgi bears,” he says.

How pandas, or any other big mammals, climb hasn’t gotten the analytic attention that techniques of squirrels and other small animals have, Schulz said. Yet rushing up a tree trunk can be a lifesaving move in the wild for pandas attacked by feral dogs. Chengdu researcher James Ayala conceived the climbing study to get the first quantitative data on emergency escape skills in captive-bred youngsters. Such information helps the Chengdu researchers judge young pandas’ chances of surviving in the wild.

For this study, the Chengdu staff built a panda climbing gym: four bark-stripped tree trunks, each a different diameter, holding up a high platform. Researchers videotaped eight young pandas, all at least a year old. The animals had grown beyond the waddling fluffball stage and were basically young teenagers with a bit of growing, and sometimes a lot of learning, left to do.

Some youngsters just didn’t get the tree thing. “No controlled ascent or descent — it was kind of madness every single time,” Schulz said of one young bear.

Others caught on, for instance reaching the pole top in eight of 10 attempts. The most successful climbers moved their heads roughly four times more than those who flubbed the poles, Schulz said. Even one female born without claws made it up the pole. The head press improves the panda grip and keeps panda weight safely balanced close to the tree.

Head-climbing looks familiar to Nicole MacCorkle, a giant panda keeper at Smithsonian’s National Zoo in Washington, D.C. She wasn’t at the meeting, but she has seen video from the Chengdu climbing tests. The zoo pandas tackle trees this way too, she says.

Although for cubs, sometimes heading up is the easy part. “They’ll climb up fairly quickly into a tree, but it seems like they can’t quite figure out how to get back down,” MacCorkle says. If cubs stay stuck too long, a keeper will come to the rescue, but, “typically they work it out for themselves.”