Gorilla Gestation Period: How Long Is a Gorilla Pregnant?

How long is a gorilla pregnant?

A gorilla carries her infant for an average of 257 days, or about 8 months and 1 week. Counting from the breeding date, birthing is normal anywhere from day 250 to day 270.

Key checkpoints across the 257-day gorilla gestation, measured in days from breeding:

Estimate your gorilla's birthing date

Enter the breeding date for an estimated birthing date at 257 days.

Gorilla gestation stages, month by month

Signs a gorilla is pregnant

• The female's monthly cycle stops
• A positive urine pregnancy test, as used in zoos
• A rounder belly from around month five or six
• Enlarged breasts and nipples in the second half of pregnancy

Signs of approaching birthing

• Resting more and moving more slowly in the final weeks
• Restlessness, building nests and staying apart from the group just before birth
• Contact your vet if labour stalls, if the animal strains without progress, or if there is abnormal discharge before birthing begins.

What affects gorilla gestation length

• A gorilla is pregnant for about eight and a half months, roughly 250 to 270 days, close to a human pregnancy.
• Gorillas usually have a single infant, weighing about 1.8 kg, which is small for such a large animal.
• As with chimpanzees, a standard human pregnancy test can confirm pregnancy, and zoos use this routinely.
• Newborn infants cling to their mother's belly. They begin riding on her back at around four months and nurse for about three to four years.
• Wild females usually give birth only once every four years or so, and may raise only a few infants in their lifetime.
• In zoos, first-time mothers sometimes struggle to care for their infants. Zoos may show them videos of other gorillas with babies or let them watch experienced mothers to help.

Gorilla gestation chart

Every fifth breeding date across the year with the matching birthing date, calculated at 257 days. Find the row closest to the date the gorilla was served; because normal gestation spans 250 to 270 days, plan for a window of a few days either side. Filter by month, or print the chart for the barn wall or breeding record: navigation, buttons and adverts are hidden on paper.

Sources for gorilla gestation figures

Figures on this page are drawn from AZA gorilla husbandry guidance, zoo great ape reproduction records and long-term field studies of wild gorillas, and checked against the references below. Averages describe healthy animals under normal management; individual animals vary, and nothing here replaces advice from your vet.

• Association of Zoos and Aquariums (AZA) — species husbandry and animal care manuals
• Smithsonian's National Zoo & Conservation Biology Institute — species fact sheets
• Published zoological studies of captive births