 The oribi is diurnal ( active mainly during the day ) , though some activity may also be observed at night . The animal rests in cover during rain events . Unlike all other small antelopes , oribi can exhibit three types of mating systems , depending on the habitat – <unk> , polygyny and <unk> ; polygyny tends to prevail as the female @-@ to @-@ male ratio increases . A study suggested that polygyny is preferred in areas of high predator risk , as it leads to formation of groups as an anti @-@ predator measure . Small herds of up to four members are also common . 
