Habitat loss, persecution and population declines have resulted in the restriction of many large carnivores, including cheetahs (Acinonyx jubatus), to fenced reserves. These reserves are often small and the likelihood of interference competition between dominant and subordinate predators is increased, while the possibility of spatial avoidance is reduced. Given artificial space limitations, subordinate predators may reduce competitive interactions along niche axes other than habitat type such as time, coined a ‘management-induced niche shift’. We collected data on the activity patterns of male and female cheetahs using continuous follows and satellite GPS collars on two small, fenced reserves in the Eastern Cape Province of South Africa, one with lions (Panthera leo) and one without lions. There was a significant difference in the activity patterns of male and female cheetahs between the two reserves. In the presence of lions, nocturnal activity of cheetahs was greatly reduced, particularly for females. There was a corresponding increase in crepuscular activity for male cheetahs and diurnal activity for female cheetahs. In the context of other studies, our results suggest that space limitation affects cheetah response to lions and provides the first quazi-experimental evidence of a management-induced niche shift.