Puku are predominantly grazers, and feed around sunrise and sunset. They are gregarious, occurring in herds averaging six individuals, but sometimes with up to 28 animals. Occasionally the smaller herds combine, forming large groups of several hundred. If danger threatens, they will whistle in alarm, trotting off nervously with their heads held erect. They also respond to the alarm signals of impala, with which they often associate. Territorial puku males herd their harems into well-defined territories, and although they tend to chase off other males, they sometimes tolerate small bachelor herds, provided their members have no sexual interest in the females. Fights between territorial males and their challengers usually result in ritualised horn-clashing only. Puku cows are not very good mothers, and the mother-calf bond is not strong. Often mothers will ignore the frantic, high-pitched bleating of their calves, and they rarely defend their young in the face of danger. Even very young calves act independently of their mothers, often running in a different direction to them when disturbed.