Order: Artiodactyla Family:
Bovidae
Scientific name: Aepyceros melampus U.S.
common name: Impala
Status in the wild: Listed as conservation
dependent. A. m. petersi of Angola and Namibia is classified as endangered by
the IUCN and USDI.
Major threats: Vulnerable to
overhunting
Geographic range currently: Kenya and southern Angola to
northern South Africa. It has disappeared from much of South Africa, but has
been introduced
in some areas outside its original range.
Habitat: Open country, woodlands,
sandy bush, and acacia savannahs.
Circadian cycle: Diurnal and nocturnal
Size
General range male female birth
Head to rump length: 1100-1600 mm 1250-1600 mm 1100-1500
mm
Tail length: 250-450 mm
Head & tail length: 1350-2050 mm
Shoulder height: 700-1000 mm 800-1000 mm 700-900
mm
Weight: 40-80 kg 45-80 kg
40-60
kg 4-5.5
kg
Sexual dimorphism: The males average slightly larger than the females. Males bear lyrate
horns, 500-910 mm long. Females do not have horns.
Reproduction
Mating Season: Year round in equatorial
areas. In South Africa, there is a peak in mating from April to June and a
lesser peak in September and October.
Birthing season: Year round with peaks in
March and November. In South Africa most births occur in November and December.
In East Africa, year round.
Gestation period: 6-7 months
Estrous cycle: 12-29 days, with estrus
lasting 24-48 hours.
Courtship: The male runs at the female
in lowstretch, snorting, wheezing, or roaring, and the female runs away and
circles back into the herd, pursued by the
male. When he relocates her he continues his pursuit. The chase
slows to a fast walk, the female keeping 3-5 m ahead of the male, which follows
flicking his tongue, often emphasized by vigorous nodding. Later
she allows him to close the distance and he proceeds to lick around her vulva
as
she walks slowly ahead, tail now held slightly away from the body.
This behavior series can be highly variable.
Copulation: The male runs or walks toward
the female while rising to stand bipedally with body erect and head high. She
usually walks forward and if he
fails to penetrate he falls forward, clasping
her with his forelegs and sometimes leaning his chest on her as he comes down.
If he penetrates, the
female usually holds still briefly.
Number of mammae: Four
Sexual maturity: Females at about 1.5 years.
Males at 13 months but usually don’t breed until their fourth year when they
gain territories.
Rearing and
young
Young called: Calf
Number of young (range): One
Condition of young: Precocial
Eyes open: At birth
Weaned: 4-7 months
General
Life expectancy: 13-15 years in the wild. Up to 17 years in captivity.
Social structure: During the dry season there
are large mixed herds of both sexes and all age classes. At other times, males
become territorial collecting
“pseudo harems” or “harems” with his territory. Unsuccessful males form bachelor
herds. Females with young form groups of 10-100
animals. Groups of females and young associate
into larger groups called clans, whose home ranges overlap. The home ranges
radiate
outwards from
fairly stable centers but there is considerable overlapping of ranges of
neighboring clans. The young of the same age often
form subgroups
or “kindergartens”. There is no lasting bond formed between individuals even
with their own young.
Unique behavior(s): When alarmed, they make
prodigious leaps of up to 9 meters. Unlike gazelles, individual distances are
very small. Also in forest areas,
they will
shove themselves into bushes and stand surrounded on all sides by shrubbery as
if in a closet. There are fetlock glands, which
are unique
to impalas, that may assist in laying trail, presumably helping “lost” individuals
find company.
Senses: Entire forehead is glandular.
Have fetlock glands with tufts of hair.
Coat & coloration: The coat is dark fawn or
reddish above and lighter on the thighs and legs. There is a vertical black
streak down each side of the
hindquarters. The underside of the body and
tail, inside upper forelegs, upper lip and chin and white. There are tufts of
black hair on the
back feet.
Dental Formula: 0/3 I, 0/1 C, 3/2-3 PM, 3/3 M
= 30-32 total
Diet: Almost entirely grazers
during the rainy season, browses on shrubs, herbs, pods and seeds during the
dry season. Drinks at least once per day.
Sources
Nowak, Ronald M. (ed.) 1999.Walker’s Mammals of the World Vol. 2 (6th edition).The
John Hopkins University Press, Baltimore and London.
Grzimek, Bernhard 1990. Grzimek’s Encyclopedia of Mammals, Vol. 5. McGraw-Hill Publishing
Company, New York.
Estes, Richard D. 1991. The Behavior Guide to
African Mammals. The University of
California Press, Berkeley.
Kingdon, Jonathan 1997. The Kingdon Field Guide to African Mammals. Academic Press, London.
Alden, Peter C. et al. 1995. National Audubon Society Field Guide to African Wildlife. Alfred A. Knopf, Inc., New York.