Reproduction

While plains zebra females live in closed membership single male groups and mate monandrously, Grevy's zebra females live in groups whose membership is much more temporary. Grevy's can be solitary or be found in herds of 6-20 animals. There are no set leaders in these herds but males seem to dominate females. Males defend individual territories. Usually female associations with individual males are brief and mating is polyandrous. Some lactating females reside with one male for longer amounts of time to be near permanent sources of water on his territory. On a typical day, adults females wander through the territories of up to four males.

Clip Art: herd of Grevy's

Young female Grevy's zebra reach puberty at 3-4 years and give birth to their first offspring at 3-6 years. Age for first reproduction is typically one to several years later for males. The typical estrous cycle for Grevy's is 28-35 days. Sexual activity is highest early in the long rain months, in July and August, and less in the short rain months of October and November. Gestation is about 13 months. The females have an average frequency of 1 young per 2 years. Young tend to be born at night in August or September. Females leave the nursing herd and enter heavy bush before birth. Delivery usually occurs with the mare on her side with limbs extended Fetal loss can be 10-18%. The mother does not return to the herd for several days so her young can imprint on her distinctive scent, call, and stripe pattern. When the maternal bond is strong she returns.

Oh baby!

Newborn Grevy's zebras weigh around 90 lbs and stand 3 ft at the shoulder. They have a wooly coat of light chocolate stripes that are darker on the head, neck, and legs. The wooly coat changes to the adult short hair, the stripes darken to black, the paler areas whiten, and the mane shortens and darkens at ~5 months. They are weaned by 9 months. Females gain independence around 13-18 months. A young male stays with his mother until at least 3 years, when he joins a bachelor group or mixed herd. Young Grevy's zebras play together by running, jumping, butting, and chasing. They also try to play with their mothers.