The female zebras remain in the same group for their entire adult life. There is a hierarchy between them to access food and water. Each female only produces milk for one young, which leaves little chance of survival for a young orphan. The young zebra begins grazing at the age of two weeks, but its mother continues to breastfeed it until it is seven months old ; it leaves its family group around the age of two or three to try to integrate into a new group.