Red duikers roam singly, in pairs, in small family groups, or in a loose asociation of 3 - 5 individuals. They browse, mostly after dark, on the leaves, stems and fruits of low-growing shrubs: they are concentrate feeders, as they cannot digest fibre very well. Their cry, mid-way between a snort and a whistle, is loud and penetrating. When the duiker is in danger or has been spotted, it will freeze, and then bound away with the charactristic duiker diving motion into the safety of thick undergrowth.

The red duiker is preyed on by eagles and pythons as well as leopards and other predators. When the duiker is in distress, its call becomes a throaty cry. The duiker's biggest threat is the clearing of its natural habitat, either for agriculture or human habitation. When the young are born, they are a reddish-black, with a reddish-brown face. Usually a single lamb is born, at any time of year.