Western lowland gorilla climbing in rainforest tree top, Cameroon

Aug

Gorillas Can’t Climb – Until They Do

greatapes2020

Dry season blossoms and seed pods draw Western lowland gorilla (Gorilla gorilla) into the rainforest tree tops of Mefou Primate Sanctuary (Cameroon.) Keepers at Ape Action Africa think nothing of seeing their charges in the highest reaches of huge emergents in the gorilla enclosure.

It never surprises me at what we discover we don’t know, or think we know. We are now going on a couple centuries of knowing gorillas in the wild, yet the idea that they might climb a tree, a really tall tree in the rainforest surprises most folks. On the other hand, I find the idea that gorillas—mountain or lowland—couldn’t climb a tree, even very high ones, a bit crazy. After all, why not? They have hands, with opposable thumbs, and feet, with opposable toes, the only thing left is a reason to climb.

For gorillas that reason is pretty simple — food. Especially for Western lowland gorillas the canopy treetop can be a bountiful world full of bright leaves, fresh fruit, savory seed-pods and maybe even a bird egg or two (pssst – gorillas are not all gentle vegetarians.) For mountain gorillas treetop ventures are a bit less lofty, but there is still value in climbing. In the cool wet forest of the Virunga Mountains and Impenetrable Forest large Hagenia trees are dripping in lush tempting ferns and lichens. For the gorillas, large and small, brave enough to climb the reward can be a tasty one. So blessed with arboreal four-wheel drive why shouldn’t you find a gorilla comfortably perched up there in the canopy. All of its ape cousins, chimps, orangutans and bonobos, find the canopy comfortable.

Gorillas live predominantly on the ground, so I might call them prudent climbers. The magic of gorillas climbing, like all apes (except us), really resides in the confidence of being able to reach for the nearly unreachable while still anchoring yourself safety with the three remaining appendages.

child compares great ape hands, Cameroon

Kids comparing hands with Western lowland gorillas. It’s not just the size of those hands that gives gorillas the confidence to climb high, but the fact that with four agile grasping appendages there is always an extra one to hold on should things get precarious. Children from Dja region school exploring Mefou Primate Park, while attending environmental education program (run by Ape Action Africa, Cameroon.)

“They spend only 5-20% of the day in trees, whereas chimpanzees spend 47-61% of the day above the ground and orang-utans almost 100%[1]. But gorillas do like to climb in order to play or access ripe fruit. Dry season blossoms and seed pods draw Western lowland gorillas into the rainforest tree tops of Mefou Primate Sanctuary in Cameroon. The Ape Action Africa keepers shrug at my amazement watching their charges reach the highest limbs of the giant emergents, they see it every day. Large male silverbacks are most hesitant to leave the ground, but even they will venture onto the lower branches where their weight can be supported. This is especially true for mountain gorillas.

Our human fear of falling has impacted captive gorillas as well. Not their choice, but that of humans, the apes that define their futures. In 1977 the Woodland Park Zoo in Seattle dared to do something many of their zoo colleagues thought foolish. The folks in Seattle built a new “immersive exhibit” for their lowland gorillas, including leaving large trees accessible to the apes. Yes, just like in the wild, gorillas could just wrap their big hairy arms around the trees and hoist themselves up as well as climb down. To everyones shock the gorillas didn’t fall and kill themselves. Today more captive facilities have realized gorillas are capable climbers and not only leave trees in new exhibits, but create artificial climbing towers for the apes.

So it was with great joy last April, while working in Cameroon, that I filmed gorillas tight-ropping the uppermost branches of huge trees in their secured patches of rainforest. In Mefou Primate Sanctuary, run by Ape Action Africa, the Western lowland gorilla orphans grow up with open access to soaring rainforest giants, many would be classified as “emergents” towering high over the canopy below by 10-20 meters (30-66 feet) — the general canopy itself 15 meters (45 feet) high.

Gorillas At Night

What has intrigued me as much about gorillas climbing is when they climb. I wake early, literally at the crack of dawn, and find them high up. The conclusion? They climb at night. After a little research I found some amazing thermal imaging film work done by Gordon Buchanan for the BBC Earth program. His film shows ghostly Grauer’s gorillas agilely climbing in the lightless tropical night. Once up there the gorillas fashion tender branches and leaves into bushy night nests (gorillas typically make two nests a day – one night and one day.)

So do gorillas fall? Well, so far I have only witnessed a tumble. That was by young mountain gorillas, and rambunctious play may have had more to do with it than dexterity in the branches. As for lowland gorillas, at least at Mefou, there seems to be little fear. On the first morning I caught them climbing I was less concerned about them falling than I was purposefully exiting their new found heights. A half hour later all my fears were put to rest by a gracefully acrobatic leap and an amazing rapid trunk clutching slide to terra firma — imagine a giant hairy you sliding down a fire pole 15-20 meters (45-66 feet.) The one feature of climbing you don’t see gorillas perform much is brachiating, commonly seen in chimps, bonobos and orangutans. Brachiating, or swinging hand over hand by rotating from the shoulder socket

Returning to Mefou in a few days I’m looking forward to see how the seasonal change (wet season) might affect climbing adventures. I was hoping to have my UAV (aka drone) ready to film the gorillas from their treetop perspective, but that will have to wait until the next visit. One things for certain, that view will surely be a dizzying one.

Notes & Source

http://www.berggorilla.org/en/gorillas/general/everyday-life/do-gorillas-often-climb-trees/
http://www.bbc.com/earth/story/20151210-rare-footage-reveals-gorillas-treetop-slumber-antics