 Typically diurnal , the oribi is active mainly during the day . Small herds of up to four members are common ; males defend their group 's territory , 25 – 100 hectares ( 62 – 247 acres ) large . The oribi is primarily a grazer , and prefers fresh grasses and browses occasionally . A seasonal breeder , the time when mating occurs varies geographically . Unlike all other small antelopes , oribi can exhibit three types of mating systems , depending on the habitat – polyandry , polygyny and polygynandry . Gestation lasts for six to seven months , following which a single calf is born ; births peak from November to December in southern Africa . Weaning takes place at four to five months . 
 Typically diurnal , the oribi <a href='drop_aux' title='1'><mark>is</mark></a>active mainly during the day . Small herds of up to four members are common ; males defend their group <a href='null_genetive' title='2'><mark>'s</mark></a>territory , 25 – 100 hectares ( 62 – 247 acres ) large . The oribi <a href='drop_aux' title='3'><mark>is</mark></a>primarily a grazer , and <a href='uninflect' title='4'><mark>prefers</mark></a> fresh grasses and browses occasionally . A seasonal breeder , the time when mating <a href='uninflect' title='5'><mark>occurs</mark></a> <a href='uninflect' title='6'><mark>varies</mark></a> geographically . Unlike all other small antelopes , oribi can exhibit three types of mating systems , depending on the habitat – polyandry , polygyny and polygynandry . Gestation <a href='uninflect' title='7'><mark>lasts</mark></a> for six to seven months , following which a single calf is born ; births peak from November to December in southern Africa . Weaning <a href='uninflect' title='8'><mark>takes</mark></a> place at four to five months . 
Typically diurnal , the oribi active mainly durin the day . Small herds of up to four members are common ; males defend their group  territory , 25 – 100 hectares ( 62 – 247 acres ) large . The oribi primarily a grazer , and prefer fresh grasses and browses occasionally . A seasonal breeder , da time when mating occur vary geographically . Unlike alll other small antelopes , oribi can exhibit three types of mating systems , depending on the habitat – polyandry , polygyny and polygynandry . Gestation last for six to seven months , following which a single calf is born ; births peak from November to December in southern Africa . Weaning take place at four to five months .