Gorilla babies are really small when they're born. They weigh between 1.5 and 2 kilos. The development of a gorilla baby goes fast. Still visitors say "look, they have so many babies here". Most of the time these babies are between 2 and 5 years old. I then tell them how old they really are and they're amazed. I then say "they develop quickly, but don't grow that quickly".
The first couple months the mother caries her baby close to her belly. Later (when depends on the mother; in general it's around 2 to 4 months) the baby moves to the back, where he/she grabs hold of mama's fur. After that, from about 4 months; but also here it depends on the mother, the baby moves to the arm or leg (again: depending on the mom. From around 3 months the babies also slowly starts crawling (so adorable to see) and tries to eat food. Most of the time mom or siblings try to steel that food That can continue for many years.
Gorilla kids have something adults don't have: a white dot on the spot where monkeys have a tail (see photo). Gorillas, orangutans, chimpanzees, bonobos and gibbons are called apes and don't have tails. Most monkeys have tails.
That white spot with gorillas is a sign of 'innocence'. In a gorilla group is a strong hierarchy (see character/behaviour/lifestyle for info about that). Babies/young kids don't really participate in that hierarchy. The can test and do things without them being punished by dad. When they get older, it's different. In the last years I saw that a lot of kids already have a deep respect for their dad, even though they still have that spot. So even though in theory they can steel food from dad, they don't out of respect.
Funny example of that white spot is something I witnessed in Apenheul many years ago. Near the end of the day the gorillas there go in and they know food is already spread throughout their entire enclosure, so each individual can sit away from another one. At that day I saw Jambo in one part eating and his son Jabari (still a baby) was right next to him. Because of his young age he was allowed to do that. He was also allowed to take Jambo's food from the floor. If another youngster had been there, he/she wouldn't dare to do that. Jambo wouldn't accept and chase that one away, but not his youngest son. So Jabari took food. Too bad Jabari's mom, Lobo, was eating at the other side of Jabari. And of course, greedy as many gorillas are, Lobo took all his food away. Too bad Jabari wasn't smart enough to go to the other side of dad I filmed this and uploaded it do YouTube. Click here to see it.
About that white spot: in various zoos they mention ages when it disappears. And those told ages differ a lot. For instance: in GaiaZOO they say 4, in another zoo they say 5. But I know one gorilla (my biggest love Shomari ) turned 9 on 12 July 2016 and still had that spot!! Since 22 July 2016 he lives in a Belgian zoo and apparently he still had it (the end of 2017). I hope to visit him this year (2018) and will check it out myself. His dad also favoured him (because of this spot??) when he was still living in his family group.
A much heard mistake of people is that gorilla kids grow quick. Most of the time these people heard or read something about it. But what they heard or read was that their development is going fast; not their growth. Gorilla babies do start crawling and walking sooner than human babies. They also start trying 'regular food' much younger while human babies still eat grinded food for a long time. But really growing goes kinda slowly, so people still call toddlers babies.
Girls are fertile around the age of 8 (often already younger) and should move around the age of 8 to another zoo with a not related male (or should be put on anti-conception). Males are normally fertile around 10, but there are gorilla boys who were able to impregnate females when they were (much) younger. One example: Bongo, living in Apenheul, was 6 when he impregnated a (also very young) female Boys can stay longer in their family group than girls. Basically as long as they don't challenge their dad. As soon as that really happens, also these boys have to move (that's between 9 and 13; all depending on their behaviour/character). Besides challenging the dad it's also possible that a young man starts to really irritate his dad's females. For gorillas in the wild it's different. Both for girls as for boys.