Instructions
Observe the size of different hippos in a group from a safe distance. Male hippos keep growing all through their lifespan of about 50 years, whereas female hippos stop growing at 25 years of age. The smaller hippos in a group of hippos of similar age are female hippos, whereas male hippos are slightly bigger.
Focus on the tusks of the different hippos to compare their lengths. The tusks of male hippos are larger than female hippos.
Look out for an aggressive hippo in a group who challenges an invading male hippo with threatening expressions to prevent it from entering its territory and joining the group. Hippo family groups consist of a male hippo living with several female hippos and their young.
Observe hippos during the rainy season when the calves are born. A female hippo will give birth to a calf which will stay by its side for about a year.