Male zebras are called stallions. Females are called mares, and young zebras are called foals. In zebra herds, stallions alert the herd to predators and serve as guardians.
Three species of zebra exist: Grevy's, mountain and plains. Grevy's zebra stallions are territorial, and mares pass through their territories to breed and foal. These zebras do not form long-term family groups. Plains and mountain zebras form family bands of one stallion, several mares and their foals. These bands live in herds of up to several hundred animals. Stallions that do not have family bands of their own either live alone or form small herds with other bachelor stallions. When hyenas or wild dogs attack a zebra band, the mares form a circle around the foals while the stallion attempts to ward off the predators.