Reproductive Behavior of Gorillas
Mountain Gorillas are polygynous, which means that the dominant males have access, and permission, to reproduce with all of the females in the group. However, the females are only able to birth an infant approximately every 4 to 5 years because she ceases to ovulate for a few years after birth. Therefore, the average number of offspring usually tends to be only one. Reproductive rates are also fairly slow, and if a female chooses to birth more than one offspring (anywhere from 2 to 6), it can be over the span of 40 years. This is why the males attempt to reproduce with more than one female, so they can increase the amount of offspring from their lineage. A male gorilla may father anywhere from 10 to 20 offspring over the course of 50 years.
Mating behavior does not begin until the gorillas are sexually mature, which is about 10 years old for females, and 15 years old for males. Gorillas usually are nursed and cared for by their mother for the first three to four years of life, and then the toddlers stay with their group until they are sexually mature to leave. Females will go out and wander by themselves in search of a new group, and males venture off when they are about 12-13, recruiting new members and bachelors for their own new troop. (This prevents inbreeding). Unlike many animals, the female is the one to initiate mating behavior by slowly approaching the male, as well as giving off a specific odor that the males will pick up on when she is ready to mate. Gorillas are also “one of the only known animals to engage in different sexual positions other than humans,” (gorillas-world.com)
Because of the time and maturity devoted to having one offspring, gorillas are said to be one of the best caregivers in the animal world. They provide the basic needs as wells as giving their children lots of affection. The mothers hold their babies similarly to human mothers and take their job of protecting their young very seriously.