 Males defend their group 's territory , 25 – 100 hectares ( 62 – 247 acres ) large ; female members may also show some aggression and drive away intruders . A study showed that the number of females that visit the male 's territory depends on the appearance ( particularly the symmetry ) of the male 's horns . Males mark vegetation and soil in their territories by <unk> <unk> <unk> and <unk> ; the intensity of marking increases with the number of male neighbours . <unk> males tend to have greater access to females in and around the territory than other males . An important feature of the social behaviour of oribi is the " dung ceremony " , in which all animals form temporary dung <unk> . Oribi at least three months old have been observed giving out one to three alarm whistles on sensing danger . These whistles are more common in adults than in juveniles , and males appear to whistle more . Common predators include <unk> such as <unk> . 
