Geographic Range
The impala is found from northeast South Africa to Angola, south Zaire, Rwanda, Uganda,and
Kenya.
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.
- Habitat Regions
- tropical
- terrestrial
- Terrestrial Biomes
- savanna or grassland
- scrub forest
Physical Description
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.
- Other Physical Features
- endothermic
- homoiothermic
- bilateral symmetry
- Sexual Dimorphism
- male larger
- ornamentation
Reproduction
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.
- Mating System
- 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.
- 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.
- Parental Investment
- altricial
-
pre-fertilization
- provisioning
-
pre-hatching/birth
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-weaning/fledging
-
provisioning
- female
-
protecting
- female
-
provisioning
- post-independence association with parents
Lifespan/Longevity
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.
- Key Behaviors
- cursorial
- terricolous
- diurnal
- motile
- territorial
- social
- dominance hierarchies
Communication and Perception
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.
- 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.
Economic Importance for Humans: Positive
- Positive Impacts
- food
Conservation 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.
Additional Links
Contributors
Barbara Lundrigan (author), Michigan State University, Karen Sproull (author), Michigan State University.
- Ethiopian
-
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- tropical
-
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
- terrestrial
-
Living on the ground.
- tropical savanna and grassland
-
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
- savanna
-
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
- temperate grassland
-
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
- scrub forest
-
scrub forests develop in areas that experience dry seasons.
- endothermic
-
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- sexual ornamentation
-
one of the sexes (usually males) has special physical structures used in courting the other sex or fighting the same sex. For example: antlers, elongated tails, special spurs.
- polygynous
-
having more than one female as a mate at one time
- iteroparous
-
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
- seasonal breeding
-
breeding is confined to a particular season
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- viviparous
-
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
- altricial
-
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
- diurnal
-
- active during the day, 2. lasting for one day.
- motile
-
having the capacity to move from one place to another.
- territorial
-
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
- social
-
associates with others of its species; forms social groups.
- dominance hierarchies
-
ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates
- food
-
A substance that provides both nutrients and energy to a living thing.
- herbivore
-
An animal that eats mainly plants or parts of plants.
- folivore
-
an animal that mainly eats leaves.
- tactile
-
uses touch to communicate
- chemical
-
uses smells or other chemicals to communicate
References
Delany, M., D. Happold. 1979. Ecology of African Mammals . New York: Longman Group Limited.
Eltringham, S. 1979. The Ecology and Conservation of Large African Mammals . New York: The Macmillan Press Limited.
Estes, R. 1991. The Behavior Guide to African Mammals . Los Angeles: The University of California Press.
Jarman, M. 1979. Impala Social Behaviour: Territory, Hierarchy, Mating,and the Use of Space . Berlin: Verlag Paul Parey.
Wilson, D., D. Reeder, eds. 1993. Mammal Species of the World . Washington, DC: Smithsonian Institution Press.