Infant gorillas are smaller than human infants when they’re born.
Gorilla moms have a roughly 8.5-month long gestation period, and infants weight about 1.4 – 1.8 kg (4 lb) when they’re born. That’s half the weight of the average human infant! However, gorillas grow faster and reach maturity around 12 years old. By the time they’re adults, gorillas end up weighing more than the average human. For males, this is between 136 – 219 kgs, or 300 – 485 lbs and for females, around 90 – 113 kg, or 200-250 lbs.
Infants typically stay in physical contact with their moms for 5 to 6 months.
Moms typically will always be in close physical contact with their infants for about half a year after they’re born. This helps keep the infant safe, lets mom keep track of the baby during active moments like foraging or traveling, and provides comfort for the infant. At around 3 months of age, gorilla infants will start to manipulate objects and explore their environment. Around 8 months, they’ll be walking and exploring within a few feet of mom. As they gets older and braver they will range further (frequently with support from siblings and other juveniles).
Mothers are the primary caregivers, but the infant’s siblings and other juveniles sometimes try to help out!
Infants and their moms remain in close proximity to each other and share a very close relationship for the infant’s first few years. Other related females will sometimes try to help out, especially young siblings of the infant. When the infant is young, the mother will try to shoo the curious gorillas away. However, as the baby gorilla gets older and starts venturing away from its mother, juveniles will participate in the young gorilla’s life. They do this through activities such as infant carrying and playing.
Mountain gorilla babies don’t know who their dad is!
Fossey Fund researchers are typically able to determine paternity through observations and genetic analysis, but gorilla infants don’t know who their dad is. There are a couple reasons for this: mountain gorilla groups can have multiple silverbacks which may have bred with the mother, or an infant’s mom may have transferred from a different group. Researchers have also determined that infants don’t show a preference for spending time with their biological fathers versus other silverbacks, further supporting the idea that the infant doesn’t know who their real dad is.
But… silverbacks assist in infant care!
Adult male mountain gorillas don’t know which infant is theirs, but they spend time caring for and socializing with older infants. One famous example is the silverback Cantsbee, who was known to “babysit” five or six infants while their mothers were foraging. Research has also shown that blackback (immature) mountain gorilla males who spend more time playing with infants and juveniles are more likely to sire offspring once they become silverbacks. For an amazing story about a silverback stepping up in a time of crisis and providing care for infants read this.