Male impalas reach sexual maturity at 4 years of age and females around 1.5 years. The female will usually give birth for the first time at the age of 3 years. During the mating season, from April to June, each adult impala ram establishes its own territory, and spends most of its time trying to keep the females and their young within the boundaries of his domain, defending it against the intrusion of other males. At this time only one ram is seen with each group of females. All young males are evicted from the herd, congregating in ┐bachelor groups┐. Males mate over a period of a month or two, first tasting the female urine for hormonal content.
Number of Young
1-2 lambs.
Gestation
190-200 days.
Birth
Normally only one lamb is born after a gestation period of around 7 months. The lamb is strong enough to walk within a couple of hours and begins moving with the herd 2-3 days after the birth. Weaning starts at about 5 months and at this time the horns of the male begin to show. By 8-9 months the males are ejected from the herd and join an all-male herd.