Reproduction Females sexually mature between the ages of 7 to 15 years but usually by the age of 9. Males sexually mature between the ages of 4 to 11 but usually by age 7. Mating season coincides with the dry season when hippo populations are concentrated at water sources. Mating usually occurs in the water and females are sometimes completely submerged. As a result females must push their heads above water to take occasional breaths of air.
Hippos reproduce about every two years in the wild.
Gestation lasts from 190 to 210 days, with births occurring during the rainy season. Mother and offspring will stay separate from the herd for 10 to 14 days after birth. Offspring are weaned about eight months after birth. Life Cycle Female hippos with offspring usually live in groups of 10 to 15 individuals, but groups of up to 150 have been reported. Adult males are solitary but sometimes form bachelor groups.