Changes in group size in Kobus kob kob (Bovidae) in the Comoe National Park, Ivory Coast (West Africa)

During a 30 month study in the Comoe National Park, Ivory Coast, it was rev ealed that median size of kob antelope groups which contained a majority of adult females varied between as well as within seasons. Group size was sma llest at the height of the rainy season and greatest at the beginning of th e rainy season. Whereas increase in group size in the beginning rainy seaso n might have been related to the improving feeding conditions and to reprod uctive behaviour, reduction of number of animals per group at the height of the rainy season was probably influenced by grass height. In addition to g rass height, other factors influencing visibility such as vegetation densit y, time of the day (day/night) and moon light intensity at night effected g roup size. While long term trends in group size changes are effected by foo d availability and reproduction, we assume visibility to be the proximate f actor influencing short term (1-24 hours) group size changes in kobs in the study area. We presume avoidance of predator attacks to be the ultimate ca use for these changes.