Impala (Aepyceros melampus)

Impala

Aepyceros melampus (Lichtenstein, 1812)

Impala female

Photo: Doug Lee

Afrikaans:Rooibok
German:Impala
French:Impala
isiNdebele:Ipala / Impala
isiZulu:iMpala
isiXhosa:Impala
seSotho:Phala
seTswana:Phala
Shona:Mhara
Shangaan:Mbala
Nama:Arab

The name impala comes from the Zulu name iMpala while the Afrikaans name “rooibok” refers to its brick-red skin colour.

IUCN Conservation Status:

Southern & East African impala = Low Risk, conservation dependent (LR/cd)
Black-faced impala = Vulnerable (VU)

Taxonomy

Classification

Supercohort:LAURASIATHERIA
Cohort:FERUNGULATA
Order:RUMINANTIA
Superfamily:BOVOIDEA
Family:BOVIDAE
Sub-family:Antilopinae
Tribe:Aepycerotini
Genus:Aepyceros
Species:melampus

Seven recognised sub-species, only three of which are accepted by the Rowland Ward trophy register:

  • Southern impala Aepyceros melampus melampus including the former sub-species A.m. johnstoni, A.m. katangae and A.m. holubi
  • East African impala Aepyceros.melampus suara from central, eastern Africa including the former sub-species A.m. rendilis
  • Black-faced impala Aepyceros melampus petersi from northern Namibia, southern Angola and north-western Botswana

The basic body form remained almost unchanged since the Miocene (6.5 million years BP) and there has never been more than one species at any given time. The body form bears a resemblance to many other bovids and taxonomists consider it to be the archetypical antelope.

Image gallery

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Description

A medium-sized, lightly built antelope. The coat is shiny, uniform chestnut brown on the back and around the neck, passing through to a light fawn on the flanks and outer leg surfaces. The belly and the inside of the legs are white. There is a prominent vertical black stripe down the centre of each buttock and on the dorsal surface of the tail. Black-faced impala are darker coloured, being a dull purple brown with a distinctive purplish-black blaze stretching down the middle of the face. East African impala are a brighter tawny red and are more sharply edged along the flanks.

Comparison To Man

Wildlife Ranching Impala comparison to man

Trophy

Lyrate-shaped, over 50 cm long and coarsely grooved for 75% of the length. The number of grooves relates to the animal’s age. Well developed horns in rams but ewes with inferior, rudimentary, deformed horns occasionally occur. Rowland Ward trophy status is reached after five years. Black-faced impala have smaller horns whereas those of the East African impala are longer with a distinctive greater tip-to-tip spread.

Habitat requirement

Bushveld, savannah, open woodland, mainly on alluvial and volcanic clay soils with an annual mean rainfall of 400 to 700 mm. Habitats with a diverse tree and shrub composition are favoured. Rocky outcrops, mountain slopes, open grasslands, marshlands, arid environments, riverine thickets and forests are avoided. Ecotones on the perimeter of riverine thickets and closed woodland are popular. The southern impala benefits from general increases in woodyfication due to global warming, and from overgrazing that increases the number of annual forbs in most woodland vegetation types. Black-faced impala prefer a denser habitat such as the riverine thickets bordering woodland vegetation.

Distribution

Wildlife Ranching Impala distribution maps

Feeding & Nutrition

Mixed, concentrate feeder and a ruminant, of both browse and short (less than 8 cm), sweet grass. Highly selective in choice of both plant species and plant parts. A low crude-fibre diet of less than 40% is required, together with high protein content of 8% in winter and 16% in summer. During moist conditions grass forms 79-92% of the diet, together with herbs, dicot forbes and little woody browse. In dry winter the lignin content of grass increases and the diet changes to 32-67% woody browse. Fallen pods are an important source of stored protein during the dry winter months.

Jumping Impala ram

Photo: Doug Lee

Social structure

Impala are social, gregarious animals that stay in groups of 6-30 in a moist summer but congregate in larger herds of 400 or more in the dry winter months following the mating season.

  • Family/breeding herds with several ewes of all ages, lambs, sub-adult rams and a few adult non-territorial rams
  • Bachelor herds that form during the rut between January and April and consist of sexually mature, but socially immature rams
  • Temporary nursing groups of youngsters that form on the outskirts of the family herds and are accompanied by 1-2 adult ewes
  • Herds of post-mature rams of 2-4 years that are mostly of trophy quality

Information Table

 

Impala information table
Characteristic
Ram
Ewe
Adult body weight
kg
57 (48-65)
41 (38-52)
Adult shoulder height
cm
85-95
80-88
Expected longevity
years
10-12
10-12
Age of sexual maturity
months
16
13
Age of social adulthood (1st mating)
years
3
1.5
Gestation
months

6.5
1st lamb born at
months

23
Lambing interval
months

12-16
Post maturity age (last mating)
years
-
-
Rutting season
Apr-Jun
Lambing season:
South Africa:
Zimbabwe
East Central Africa:
Black Faced Impala:


Oct-Dec
Nov-Jan
Entire year
Dec-Jan
Weaning age months
3
Gender ratio: natural (all ages)
1
1.1
Gender ratio: production (all ages)
1
1.6
Mating ratio: natural (adults)
1
3
Mating ratio: production (adults)
1
5
Re-establishment: absolute minimum number needed
2
3
Re-establishment: smallest viable population size
5
12
Spatial behaviour: home Range
ha
200-400
250-700
Spatial Behaviour: territory range
ha
4-10
None
Large stock grazing unit (adult):
Dietary ratio (grass):
LSU
0.17 per animal
(45% of diet)
0.17 per animal
(45% of diet)
Browsing unit (adult):
Dietary ratio: (browse):
BU
0.4 per animal
(55% of diet)
0.4 per animal
(55% of diet)
Maximum stocking load
300 animals per 1000 ha (at 350-450 mm annual rainfall)
Minimum habitat size required
ha
150
Annual population growth
23-48% (mean 35%)

Bibliography

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