Zebras reproduce sexually: The male zebra, which is called a stallion, mounts a female zebra, which is called a mare, and deposits sperm in the mare's vagina via the stallion's penis. If the mating is successful, the mare births a single foal 12 to 13 months later.
Zebra herds typically consist of a stallion and several mares, comprising a group known as a harem. Stallions compete with one another to lay claim to a harem. Once a stallion emerges victorious, his claim is challenged only when other stallions perceive weakness due to disease or injury.
Stallions reach sexual maturity at 4 years old, while mares reach sexual maturity between 2 and 4 years old. Like other equine species, a zebra mare in estrus — that is, in heat — often signals her willingness to breed with a stallion by "winking" the labia, or turning them outward.
The long gestation period observed in zebras allows a foal to develop sufficiently that, within minutes of being born, it is able to stand. In spite of this developmental advantage, infant mortality among zebra foals is approximately 50 percent. If the foal reaches maturity, the average expected lifespan in the wild is between 20 and 25 years.