Gorillas are one of the rare wildlife species, the world’s largest living primate, only found in the lush forests of Central and Eastern Africa.
Gorillas are the closest relatives to humans with whom they share about 98% of their genetic code, they only come third after bonobos and chimpanzees. Gorillas are charming creatures with emotions, they get annoyed and can sometimes laugh or express joy and mood swings.
These primates move with their four legs even though sometimes they tend to stand tall especially when feeding. Silverbacks are the dominant male gorillas and are considered the leaders though much heavier than female gorillas at about 220 kilograms. Gorillas are characterized by thick heavy muscular arms and chests like that of human with their visible large nostrils.
There are two subspecies of gorillas including the Eastern gorillas and western gorillas. Western gorillas are divided into two subspecies including western lowland gorillas and cross-river gorillas. The Eastern gorillas are also made up of two gorilla sub-species including the mountain gorillas and the eastern lowland gorillas.
Mountain gorillas are the rarest among the gorillas, only found in the Virunga ranges that span three countries that is Uganda, Rwanda and DR.Congo.
Gorilla Groups and Family Hierarchy
Gorillas are social creatures living in families/groups consisting of various family members including infants, juveniles, adult males and females under a leadership of a dominant male (The Silverback) who leads the group and the activities to do.
Gorilla groups usually contain about 30 individuals and are known for their peaceful nature, with some internal conflicts. Interactions between different gorilla groups are rare, although they have been noted among the western lowland subspecies. The rare occasion explains why it is not possible to encounter all the gorillas on one gorilla trek, you have to visit one gorilla family at a time.
Gorilla families are always attacked by lone males purposely to challenge the silverback and his leadership, resulting into violent confrontations. The silverback, with the help of other mature male gorillas, can defend his family in such cases.
Breeding In Gorillas
In all gorilla groups, the dominant male known as the Silverback, breeds with all the females. Mating occurs year-round and is usually initiated by the females, regardless of whether they are in estrus. Both western and eastern gorillas are known to mate while facing the same side, though instances of face to face mating have been observed, particularly among mountain gorillas.
Sexual Maturity and Reproduction in Gorillas
Female gorillas reach sexual maturity between the ages of 10 and 12, although their ovulation cycle begins earlier, around age 6. However, they remain infertile until they reach full maturity at age of 10. Many females leave their maternal families/groups to avoid inbreeding, while those that stay attempt to avoid mating with their fathers, often choosing less dominant males instead.
In contrast, male gorillas leave the group upon reaching maturity, either becoming loners or start their own gorilla families. Later, they may steal females from other gorilla families to form their own families. Despite the strong bonds the dominant silverback forms with the females of his group, as he ages and his reproductive capacity declines, the females often leave to join other groups. Some females may stay loyal to the dominant silverback, but after his demise they will ultimately join other groups. Females may change groups multiple times to protect their offspring, especially if a new dominant silverback takes over.
How Gorillas Mate
Gorillas mate throughout the year, with the dominant silverback mating with all the females in the group while ovulating. Usually, mating is initiated by the sexually active female, though the silverback may also initiate by approaching the female, touching her, or making displays with sounds. If the female does not respond positively, the silverback may react aggressively, charging or slapping the female to force her into acceptance.
Mating in gorillas typically occurs on the ground with the female (usually smaller than the dominant silverback) kneeling while the male copulates on top. However, some subspecies, such as mountain gorillas and lowland gorillas have been observed mating face to face, a behavior once thought to be unique to human and bonobos.
Signs a Female Gorillas is ready to Mate
Unlike other primates like chimpanzees, female gorillas don’t show physical changes when they are ready to mate. Instead, a female gorilla signals her readiness by gently approaching the male, pressing her lips together, and making prolonged eye contact with him. If the male does not respond to her advances, she may slap the ground and move towards him to attract his attention.
Sometimes, if the dominant male is unresponsive or preoccupied, the female may mate with less dominant males in the group.
According to the study conducted in 1982, aggression from the silverback towards a particular female was revealed. She was compelled to initiate mating even when not in estrus.
Do Gorillas only mate for Reproduction?
Generally, gorillas do not mate for leisure or competition. However, females often mate to gain favor with the dominant silverback and prevent him from mating with over females in the group. Expectant females have been known to mate with the silverback to prevent him from impregnating other females ready to mate.
Silverbacks typically prefer mating with experienced adult females, which can lead to competition among the female gorillas. In western gorilla species, silverbacks may mate with females regardless of their ovulation status, though most females will only mate when they are sexually ready.
Reproduction and Parenthood
After a successful mating and a female gorilla conceiving, she undergoes an 8.5 month gestation period and gives birth about every four years. During pregnancy, the female’s breast size increases slightly and she develops a subtle tummy bump. Birth typically occurs in the morning, often preceded by the female’s restlessness, stretching, and loss of appetite.
Throughout her lifetime, a female gorilla may give birth to six to eight babies, but only few are likely to survive to maturity as the females provides all of the care. The silverback also plays a crucial role in ensuring the babies are accepted within the group and are not bullied by other family members. For the first five months, the mother stays close to the silverback for protection.
