Grouping patterns and spatial segregation by Nubian ibex

Social organization and space use patterns of sexually size dimorphic Nubian ibex (Capra ibex nubiana) were studied for 26 months in the northern Negev Desert, Israel. The main social units were: female/kid groups that also contained young males up to 3-years-old, immature male (4–6-years-old), mature male (more than 6-years-old), and mixed groups. Mature males and females were in separate groups except during rut, when mature males moved into areas occupied by females and were equally likely to be seen in female/ kid, mature male, or mixed groups. Outside the rut, 89% of female sightings were in 4 ha quadrats in which no mature males were seen, but there was a dramatic increase in spatial overlap of adult males and females during the rut as the males moved into the same areas as females. Young males were found almost exclusively in female/kid groups ( > 90% of observations), but as body size of growing males surpassed that of females, they were more frequently associated with other groups. The pattern of sexual segregation of groups and space, and the age at which males left groups dominated by females and kids, is consistent with a nutritional hypothesis of foraging patterns and social organization for sexually dimorphic herbivores.