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By Barbara Lundrigan and Karen Sproull
Geographic Range
The impala is found from northeast South Africa to Angola, south Zaire, Rwanda, Uganda,and Kenya. (Wilson, Reeder, and eds, 1993)
Habitat
The impala is found in woodland which contains little undergrowth and low to medium height grassland. Also a close source of water is desired, however is not needed when there is abundance of grass. (Estes, 1991)
These animals are found in the following types of habitat:
tropical 
; terrestrial .
Terrestrial Biomes:
savanna or grassland ; scrub forest .
Physical Description
(99 to 132 lbs; avg. 115.5 lbs)
Impala are sexually dimorphic. In this species only the males have S shaped horns that are 45 to 91.7 cm long. These horns are heavily ridged, thin, and the tips lie far apart. Both sexes are similarly colored with red-brown hair which pales on the sides. The underside of the belly, chin, lips, inside ears, the line over the eye, and tail are white. There are black stripes down the tail, foreheard, both thighs, and eartips. These black stripes might aid in recognition between individuals. Aepyceros melampus also have scent glands on their rear feet beneath patches of black hair as well as sebaceous glands on the forehead. (Estes, 1991; Jarman, 1979)
Some key physical features:
endothermic ; homoiothermic; bilateral symmetry .
Sexual dimorphism: male larger, ornamentation .
Reproduction
Impalas breed once a year.
Most breeding occurs in March through May.
Males test the females' urine to detect estrous. The male then roars, snorts, or low stretches to advertise himself. After chasing the female, the male may show behaviors such as nodding and tongue flicking before copulation. (Eltringham, 1979; Estes, 1991; Jarman, 1979)
Mating systems:
polygynous .
Female impalas are reproductively mature and conceive at 1.5 years. Males have the ability to breed at age 1, but often do not establish territories until age 4. Most breeding occurs in March through May. Gestation is 194-200 days. (Eltringham, 1979; Estes, 1991; Jarman, 1979)
Key reproductive features:
iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous .
The female impalas isolate themselves before calving. Calving usually occurs in the midday. Usually there is only one calf. The mother and calf will rejoin the herd after 1-2 days. Impalas place the young in creches which are groups of young that play, groom, and move together. Young impala are weaned at 4.5 months. (Eltringham, 1979; Estes, 1991; Jarman, 1979)
Parental investment:
altricial ; pre-fertilization (provisioning); pre-hatching/birth (provisioning: female, protecting: female); pre-weaning/fledging (provisioning: female, protecting: female); post-independence association with parents.
Behavior
Impala are diurnal and spend the night ruminating and lying down. The peak activity times for social activity and herd movement are shortly after dawn and before dusk.
Impala have different social structures depending on the season. The average size of the female herd is between 15-100 individuals depending on space available. Females live in clans within a home range of 80-180 ha. During the wet season the ranges are heavily defended, but during the dry season there is much overlap between individuals in the clan and even between different clans. There are slight differences between behavior in southern and eastern impala. Southern impala are more likely to intermix during the dry season, while eastern impala will remain more territrorial during the dry season.
Impala form distinct social groups during the wet season. Three main organizations are found: territorial males with and without breeding females, bachelor herds of non-territorial adult and juvenile males, and breeding herds of females and juveniles (including young males less than 4 years). During the dry season, males can be found together or mixed with female herds.
The male impala changes its territory to match the season. During the breeding season the male keeps a much smaller territory which is heavily defended. The males will imprint on their original territory and always come back to that same territory to declare dominance.
The male impala uses a variety of techniques to defend its territory (including keeping females). Tail-raising, forehead marking, forehead rubbing, herding, chsing, erect posture, fighting, and roaring are used. (Estes, 1991; Jarman, 1979)
Key behaviors:
cursorial; terricolous; diurnal ; motile ; territorial ; social ; dominance hierarchies .
Food Habits
Impala are ruminants. The upper incisors and canines are absent and the cheek teeth are folded and sharply ridged. Impala are intermediate feeders. While predominately a grazer, the impala will adapt to any amount of grass and browse. Impala feed mostly on grass during times of lush growth following the rains and will switch to browse during the dry season. (Estes, 1991; Jarman, 1979)
Plant Foods:
leaves; wood, bark, or stems.
Predation
Aepyceros melampus uses various antipredatory techniques as well. The most common is to take flight and outrun or confuse the predator. Commonly impala will leap up or 3 meters in the air. They often leap up or out in any direction to confuse the predator. Another unique characteristic of leaping is when impala land on their front legs and kick the back legs into the air. (Estes, 1991; Jarman, 1979)
Conservation Status
IUCN Red List: [link]:
Lower Risk - Conservation Dependent.
US Federal List: [link]:
Endangered.
CITES: [link]:
No special status.
Aepyceros melampus petersi is listed as endangered by the U.S. ESA and IUCN. Pressure resulting from habitat loss and damage have been linked to the decline in impala numbers. (Delany and Happold, 1979; Wilson, Reeder, and eds, 1993)
Contributors
Barbara Lundrigan (author), Michigan State University. Karen Sproull (author), Michigan State University.
