Zebra black and white at birth. Plains and mountain zebra foals are protected by their mothers, as well as the head stallion and the other mares in their group. Grévy's zebra foals have only their mother as a regular protector, since, as noted above, Grévy's zebra groups often disband after a few months. Attempts have been made to train zebras for riding, since they have better resistance than horses to African diseases. While occasionally successful, most of these attempts failed due to the zebra's more unpredictable nature and tendency to panic under stress. For this reason, zebra-mules or zebroids (crosses between
Zebra zeedonk, zony, and zorse. In certain regions of Kenya, plains zebras and Grévy's zebra coexist, and fertile hybrids occur. The Hagerman horse ("Equus simplicidens") is sometimes referred to as the American zebra due to perceived similarities to the plains zebra, and sometimes depicted as striped. However, consensus appears to be that it wasn't particularly closely related to either "Hippotigiris" nor "Dolichohippus", nor is there unambiguous evidence that it had stripes. The common plains zebra is about at the shoulder with a body ranging from long with a tail. It can weigh up to , males being slightly bigger than females.