Gorillas are very strong animals. They are seven times stronger than we are. How they calculated that is a mystery to me. But yes, they are many times stronger. If you see young gorillas already break branches ... But it is also evident from the fact that a baby of a few months (and sometimes even a few days or a few weeks!) old can hold on to mom when he/she is carried on the back. In the first stage they sit -as read elsewhere- on the belly and then mother supports them. But when they move to their back, to have to hold on to mom's fur.
I once heard a story that in an American zoo a tug-of-war was held through wire mesh between a silverback and x number of strong men. I just don't know the literal text anymore and I can't find anything about it on the internet; I think only 12 men could win. I'll keep my ears open (I think I heard the story at a presentation in Apenheul) and adjust this text when I know more about it.
A story I do remember is from a keeper in Apenheul. In the indoor enclosure the sliding doors go from left to right (in many other zoos from top to bottom). Once a young gorilla girl of 6 years old sitting in one of those open doors. The keeper tried to close the doors gently, but the girl held the door with one hand. The keeper tried to push harder, but she couldn't! So what a power that little one already had.
That 'brute force' also means that the keepers have not visited the gorillas in Apenheul on the island for years. In the early years they did. Now I've heard two different stories about why they don't do that anymore. One is that a new female arrived who was not used to having keepers in the group. That's why they stopped. The other story is that teenagers and toddlers enjoyed playing with those keepers. But since they are so strong, they (totally unintentionally) hurt their keepers.
On 28 May 2021 I was able to see for myself how strong gorillas are. Since the day before, Chama had been added to the mini group that already consisted of Jabari and MFugaji. Miss Chama did not agree to being in that group. She was restless and wanted to go back to Bao Bao and the others. She regularly climbed trees and made various noises.
Eventually I ended up with them again and she had a log that she wanted to use to cross the water. I myself took a few photos that you can see below, but Mike Rodenburg was there a little earlier and he had filmed the whole thing. You can see his video on Facebook -> https://fb.watch/v/4QfqpeInr/
As you can see, she quite easily lifts a tree trunk to put it upright in the water. Chama is a young lady, 9 years old at the time of the video.
I went to the keepers to report her action. She dragged the branch onto their island after the failed action. I was afraid she would take it further on the island and do something with it. Next to their island is the island of capuchin monkeys. That distance seemed shorter to me and it didn't seem convenient that she would end up there via that branch, because who knows where she could go next …
The keeper to whom I told called the gorilla keeper on duty. He soon came to have a look and saw that the branch indeed had to be removed. He made sure the 3 young gorillas went to their enclosure and he went onto the island.
I kept watching and to my amusement he (an adult man!!) couldn't lift the branch; young Chama did it effortlessly. To be honest, I would have loved to film and/or photograph this, but I respect all gorilla keepers in all zoos and would like to stay friends with them. The keeper who was there is always very funny and he tried to get me away by shouting "Have you seen the spider monkey baby that was born this morning?". But I didn't fall for that. I kept watching with pleasure (and I think I shouted something along the lines of 'can a young gorilla girl pick up/drag that branch and you can't??!!').
Finally it was decided to throw a rope from the capuchin island to the gorilla island, so that the keeper could then put it around the branch. This way that branch could then be pulled to the capuchin island. It took some time, because throwing a rope over water is not so easy either, but in the end it worked. The branch in question was placed against a climbing structure of the capuchin monkeys.
Four photos I took:
