Friday, September 18

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.”