Answer:
Female gorillas are the usual instigators of mating. When a female comes into her monthly cycle she starts staring at the silverback, often with her lips tucked in and following him around. She may also touch him up, slap the ground, sit in his lap and masturbate in front of him to get him going as some male gorillas need a bit of a stimulation to get them in the mating mood! Males can also start the routine by posturing, flexing their muscular bodies, chestbeating, stancing and generally showing off in front of the female which can be very beautiful and awesome to see, but it is usually the female that starts the ritual. Gorillas have been seen mating face to face like humans, but the more usual posture is the male mounts the female from the rear. This goes on for a few days each month until she gets pregnant. Gorillas also mate during pregnancy but once the young one is born there is usually a break in mating activity for a few years.