Small gorillas grow a white patchon the rump after a month or so. Why? It's hard to know, but they do lose that white hair, at about the age of three or so, around the same time they are weaning.
helps the mom to keep track of her baby. But I have never seen either mother at the NC Zoo, neither Olympia, nor Jamani, fail to know where her own baby is! Others say the white lets other gorillas know the animal is an infant. But would that not be obvious from their tiny size? Male gorillas have that little white patch, as seen here in this picture of what some would call the wrong end of Bomassa. And females have it too. Patty Gorilla, daughter of our own Kwanzaa (now known as Kwan, and living in Chicago) has a beautiful little white patch as well!