Impalas have an unusually loose social structure. Groups join and separate into herds of different sizes with no regard to territories or individuals. The size of a herd depends on the habitat and can range from 4 to 150 members. The largest groups tend to be found in more open habitats. Impalas form three types of groups: bachelor groups, breeding groups, and territorial males. A fourth group, the nursery herd, may form for a few months after births occur. The bachelor groups are composed of juveniles, sub-adults, or adult males. They are organized in a hierarchy based on age and move frequently, concentrating on areas with lower quality vegetation.
Impalas communicate through sight, sound, and smell as well as with physical displays, such as kicks and tongue flashing. Unlike other kinds of antelopes, impalas communicate vocally by “roaring” at a very high volume. The roars of dominant males can be heard up to 1.2 miles (2 km) away, giving them a reputation for being one of the loudest and noisiest ungulates before the breeding season.
Impalas are mostly active during the day, alternating their time between moving, resting, feeding, and grooming. At night, they spend most of their time lying down or ruminating. Impalas are the only ungulates known to engage in a form of reciprocal grooming called allogrooming. Their teeth are specially designed and positioned to scour through another’s (or their own) hair and remove any ticks with ease. Allogrooming occurs frequently between all individuals, regardless of status, kin, or sex. Male impalas are very territorial and use threat displays, confrontations, and outright fighting to defend their territories. Fights generally occur only when two males both try to assert their dominance.
Impala populations remain very widespread, despite some decreases in parts of their range. However, two of their greatest survival tactics have become their biggest survival risks: Their high rate of reproduction and incredible adaptability have made them particularly tempting as a meat source. Even though many impala live in protected regions, poaching threatens them on the boundaries of these areas.