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== Taxonomy and evolution ==
== Taxonomy and evolution ==


[[File:Black-faced Impala (Aepyceros petersi) (8603213327).jpg|thumb|right|The black-faced impala, a subspecies of the impala]]
[[File:Black-faced Impala (Aepyceros petersi) (8603213327).jpg|thumb|right|alt=A female black-faced impala|The black-faced impala, a subspecies of the impala]]


The impala is the sole member of the [[genus (biology)|genus]] ''Aepyceros'' and belongs to the [[family (biology)|family]] [[Bovidae]]. It was first [[scientific description|described]] by German zoologist [[Martin Hinrich Carl Lichtenstein]] in 1812.<ref name =MSW3>{{MSW3 Artiodactyla | id = 14200488 | pages = 673}}</ref> In 1845, Swedish zoologist [[Carl Jakob Sundevall]] placed the springbok in ''Antidorcas'', a genus of its own.<ref name="Sundevall">{{cite journal |last1 = Sundevall |first1 = C.J. |authorlink = Carl Jakob Sundevall |title = Melhodisk öfversigt af Idislande djuren , Linnés Pecora |journal = Kungl. Svenska Vetenskapsakademiens Handlingar |date = 1844 |page = 271 |url = http://www.biodiversitylibrary.org/item/182326#page/795/mode/1up |series = 3 |language = Swedish }} {{open access}}</ref>
The impala is the sole member of the [[genus (biology)|genus]] ''Aepyceros'' and belongs to the [[family (biology)|family]] [[Bovidae]]. It was first [[scientific description|described]] by German zoologist [[Martin Hinrich Carl Lichtenstein]] in 1812.<ref name =MSW3>{{MSW3 Artiodactyla | id = 14200488 | pages = 673}}</ref> In 1845, Swedish zoologist [[Carl Jakob Sundevall]] placed the springbok in ''Antidorcas'', a genus of its own.<ref name="Sundevall">{{cite journal |last1 = Sundevall |first1 = C.J. |authorlink = Carl Jakob Sundevall |title = Melhodisk öfversigt af Idislande djuren , Linnés Pecora |journal = Kungl. Svenska Vetenskapsakademiens Handlingar |date = 1844 |page = 271 |url = http://www.biodiversitylibrary.org/item/182326#page/795/mode/1up |series = 3 |language = Swedish }} {{open access}}</ref>
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== Description ==
== Description ==


[[File:ImpalaSerengetiNationalParkMar2011.jpg|thumbnail|left|Close view of a male. Note the lyre-shaped horns, white tail and several black markings.]]
[[File:ImpalaSerengetiNationalParkMar2011.jpg|thumbnail|left|alt=A grooming male at Serengeti National Park|Close view of a male. Note the lyre-shaped horns, white tail and several black markings.]]


The impala is a medium-sized, slender [[antelope]] similar to the [[kob]] or [[Grant's gazelle]] in build.<ref name="estes">{{cite book |last = Estes |first = R.D. |authorlink = Richard Despard Estes |title = The Behavior Guide to African Mammals: Including Hoofed Mammals, Carnivores, Primates |year = 2004 |publisher = University of California Press |location = Berkeley, US |isbn = 978-0-520-08085-0 |pages = 158–66 |edition = 4th }}</ref> The head-and-body length is around {{convert|130|cm|in}}.<ref name="Liebenberg">{{cite book |last1 = Liebenberg |first1 = L. |title = A Field Guide to the Animal Tracks of Southern Africa |date = 1990 |publisher = D. Philip |location = Cape Town, South Africa |isbn = 978-0-86486-132-0 |pages = 275–6 }}</ref> Males reach approximately {{convert|75|-|92|cm|in}} at the shoulder, while females are {{convert|70|-|85|cm|in}} tall. Males typically weigh {{convert|53|-|76|kg|lb}} and females {{convert|40|-|53|kg|lb}}. [[Sexual dimorphism|Sexually dimorphic]], females are hornless and notably smaller than males. Males grow {{convert|45|-|92|cm|in}} long, slender, lyre-shaped horns.<ref name="estes" /> The horns, strongly ridged and divergent, circular in section and hollow at the base. Their arch-like structure allows interlocking of horns, which helps a male throw off his opponent during fights; horns also protect the skull from damage.<ref name="kingdon" /><ref name="estes" />
The impala is a medium-sized, slender [[antelope]] similar to the [[kob]] or [[Grant's gazelle]] in build.<ref name="estes">{{cite book |last = Estes |first = R.D. |authorlink = Richard Despard Estes |title = The Behavior Guide to African Mammals: Including Hoofed Mammals, Carnivores, Primates |year = 2004 |publisher = University of California Press |location = Berkeley, US |isbn = 978-0-520-08085-0 |pages = 158–66 |edition = 4th }}</ref> The head-and-body length is around {{convert|130|cm|in}}.<ref name="Liebenberg">{{cite book |last1 = Liebenberg |first1 = L. |title = A Field Guide to the Animal Tracks of Southern Africa |date = 1990 |publisher = D. Philip |location = Cape Town, South Africa |isbn = 978-0-86486-132-0 |pages = 275–6 }}</ref> Males reach approximately {{convert|75|-|92|cm|in}} at the shoulder, while females are {{convert|70|-|85|cm|in}} tall. Males typically weigh {{convert|53|-|76|kg|lb}} and females {{convert|40|-|53|kg|lb}}. [[Sexual dimorphism|Sexually dimorphic]], females are hornless and notably smaller than males. Males grow {{convert|45|-|92|cm|in}} long, slender, lyre-shaped horns.<ref name="estes" /> The horns, strongly ridged and divergent, circular in section and hollow at the base. Their arch-like structure allows interlocking of horns, which helps a male throw off his opponent during fights; horns also protect the skull from damage.<ref name="kingdon" /><ref name="estes" />
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== Ecology and behaviour ==
== Ecology and behaviour ==


[[File:Impala AdeFrias.jpg|thumbnail|Impala can leap up to {{convert|3|m|ft}}.]]
[[File:Impala AdeFrias.jpg|thumbnail|alt=An impala mid-air during a leap|Impala can leap up to {{convert|3|m|ft}}.]]


The impala is [[diurnality|diurnal]] (active mainly during the day), though activity tends to cease during the hot midday hours; the night is spent in feeding and resting.<ref name=estes /> Three distinct social groups can be observed{{snds}}the [[Territory (animal)|territorial]] males, bachelor herds and female herds.<ref name=schenkel>{{cite journal |last = Schenkel |first = R. |title = On sociology and behaviour in impala (''Aepyceros melampus'') Lichtenstein |journal = [[African Journal of Ecology]] |year = 1966 |volume = 4 |issue = 1 |pages = 99–114 |doi = 10.1111/j.1365-2028.1966.tb00887.x }}</ref> The territorial males hold territories where they may form [[Harem (zoology)|harems]] of females; territories are demarcated with urine and faeces and defended against juvenile or male intruders.<ref name=estes /> Bachelor herds tend to be small, with less than 30 members. Individuals maintain distances of {{convert|2.5|-|3|m|ft}} from one another; while young and old males may interact, middle-aged males generally avoid one another. The membership of female herds varies from 6 to 100; herds occupy {{convert|80|-|180|ha|acre sqmi|lk=on}} large [[home range]]s. The mother-calf bond is weak, and breaks soon after weaning; juveniles leave the herds of their mothers to join other herds. Female herds tend to be loose and have no distinct leadership.<ref name=estes /><ref name=murray>{{cite journal |last = Murray |first = M.G. |title = Structure of association in impala, ''Aepyceros melampus'' |journal = [[Behavioral Ecology and Sociobiology]] |date = 1981 |volume = 9 |issue = 1 |pages = 23–33 |doi = 10.1007/BF00299849 }}</ref> Allogrooming is an important means of social interaction in bachelor and female herds; in fact, the impala appears to be the only [[ungulate]] to display self-grooming as well as allogrooming. In allogrooming, females typically groom related individuals, while males associate with unrelated individuals. Each partner grooms the other six to twelve times.<ref name="hart">{{cite journal |last1 = Hart |first1 = B.L. |last2 = Hart |first2 = L.A. |title = Reciprocal allogrooming in impala, ''Aepyceros melampus'' |journal = [[Animal Behaviour (journal)|Animal Behaviour]] |year = 1992 |volume = 44 |issue = 6 |pages = 1073–83 |doi = 10.1016/S0003-3472(05)80319-7 }}</ref>
The impala is [[diurnality|diurnal]] (active mainly during the day), though activity tends to cease during the hot midday hours; the night is spent in feeding and resting.<ref name=estes /> Three distinct social groups can be observed{{snds}}the [[Territory (animal)|territorial]] males, bachelor herds and female herds.<ref name=schenkel>{{cite journal |last = Schenkel |first = R. |title = On sociology and behaviour in impala (''Aepyceros melampus'') Lichtenstein |journal = [[African Journal of Ecology]] |year = 1966 |volume = 4 |issue = 1 |pages = 99–114 |doi = 10.1111/j.1365-2028.1966.tb00887.x }}</ref> The territorial males hold territories where they may form [[Harem (zoology)|harems]] of females; territories are demarcated with urine and faeces and defended against juvenile or male intruders.<ref name=estes /> Bachelor herds tend to be small, with less than 30 members. Individuals maintain distances of {{convert|2.5|-|3|m|ft}} from one another; while young and old males may interact, middle-aged males generally avoid one another. The membership of female herds varies from 6 to 100; herds occupy {{convert|80|-|180|ha|acre sqmi|lk=on}} large [[home range]]s. The mother-calf bond is weak, and breaks soon after weaning; juveniles leave the herds of their mothers to join other herds. Female herds tend to be loose and have no distinct leadership.<ref name=estes /><ref name=murray>{{cite journal |last = Murray |first = M.G. |title = Structure of association in impala, ''Aepyceros melampus'' |journal = [[Behavioral Ecology and Sociobiology]] |date = 1981 |volume = 9 |issue = 1 |pages = 23–33 |doi = 10.1007/BF00299849 }}</ref> Allogrooming is an important means of social interaction in bachelor and female herds; in fact, the impala appears to be the only [[ungulate]] to display self-grooming as well as allogrooming. In allogrooming, females typically groom related individuals, while males associate with unrelated individuals. Each partner grooms the other six to twelve times.<ref name="hart">{{cite journal |last1 = Hart |first1 = B.L. |last2 = Hart |first2 = L.A. |title = Reciprocal allogrooming in impala, ''Aepyceros melampus'' |journal = [[Animal Behaviour (journal)|Animal Behaviour]] |year = 1992 |volume = 44 |issue = 6 |pages = 1073–83 |doi = 10.1016/S0003-3472(05)80319-7 }}</ref>
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=== Parasites ===
=== Parasites ===


[[File:Impala mutualim with birds wide.jpg|thumb|Impala have a [[symbiosis|symbiotic]] relationship with [[oxpecker]]s]]
[[File:Impala mutualim with birds wide.jpg|thumb|alt=Red-billed oxpeckers feeding on parasites on a male|Impala have a [[symbiosis|symbiotic]] relationship with [[oxpecker]]s]]


Common [[ixodid]] ticks collected from impala include ''[[Amblyomma hebraeum]]'', ''[[Boophilus decoloratus]]'', ''[[Hyalomma marginatum]]'', ''[[Ixodes cavipalpus]]'', ''[[Rhipicephalus appendiculatus]]'' and ''[[Rhipicephalus evertsi|R. evertsi]]''.<ref name=Mooring1995>{{cite journal |last1 = Mooring |first1 = M.S. |title = The effect of tick challenge on grooming rate by impala |journal = [[Animal Behaviour (journal)|Animal Behaviour]] |date = 1995 |volume = 50 |issue = 2 |pages = 377–92 |doi = 10.1006/anbe.1995.0253 |url = http://www.pointloma.edu/sites/default/files/filemanager/Biology/Faculty/Mooring/Publications/1995-Tick_challenge_impala_grooming_Anim_Behav.pdf }}</ref><ref>{{cite journal |last1 = Gallivan |first1 = G.J. |last2 = Culverwell |first2 = J. |last3 = Girdwood |first3 = R. |last4 = Surgeoner |first4 = G.A. |title = Ixodid ticks of impala (''Aepyceros melampus'') in Swaziland: effect of age class, sex, body condition and management |journal = South African Journal of Zoology |date = 1995 |volume = 30 |issue = 4 |pages = 178–86 |doi = 10.1080/02541858.1995.11448385 |url = http://www.tandfonline.com/doi/pdf/10.1080/02541858.1995.11448385 }} {{open access}}</ref><ref>{{cite journal |last1 = Horak |first1 = I.G. |title = Parasites of domestic and wild animals in South Africa. XV. The seasonal prevalence of ectoparasites on impala and cattle in the Northern Transvaal |journal = The Onderstepoort Journal of Veterinary Research |date = 1982 |volume = 49 |issue = 2 |pages = 85–93 |pmid = 7177586 }}</ref> In Zimbabwe, heavy infestation by ticks such as ''R. appendiculatus'' has proved to be a major cause behind the high mortality of ungulates, as they can lead to [[tick paralysis]]. Impala have special adaptations for grooming, such as their characteristic dental arrangement, to manage ticks before they engorge; however, the extensive grooming needed to keep the tick load under control involves the risk of dehydration during summer, lower vigilance against predators and gradual wearing out of the teeth. A study showed that impala adjust the time devoted to grooming and the number of grooming bouts according to the seasonal prevalence of ticks.<ref name=Mooring1995 />
Common [[ixodid]] ticks collected from impala include ''[[Amblyomma hebraeum]]'', ''[[Boophilus decoloratus]]'', ''[[Hyalomma marginatum]]'', ''[[Ixodes cavipalpus]]'', ''[[Rhipicephalus appendiculatus]]'' and ''[[Rhipicephalus evertsi|R. evertsi]]''.<ref name=Mooring1995>{{cite journal |last1 = Mooring |first1 = M.S. |title = The effect of tick challenge on grooming rate by impala |journal = [[Animal Behaviour (journal)|Animal Behaviour]] |date = 1995 |volume = 50 |issue = 2 |pages = 377–92 |doi = 10.1006/anbe.1995.0253 |url = http://www.pointloma.edu/sites/default/files/filemanager/Biology/Faculty/Mooring/Publications/1995-Tick_challenge_impala_grooming_Anim_Behav.pdf }}</ref><ref>{{cite journal |last1 = Gallivan |first1 = G.J. |last2 = Culverwell |first2 = J. |last3 = Girdwood |first3 = R. |last4 = Surgeoner |first4 = G.A. |title = Ixodid ticks of impala (''Aepyceros melampus'') in Swaziland: effect of age class, sex, body condition and management |journal = South African Journal of Zoology |date = 1995 |volume = 30 |issue = 4 |pages = 178–86 |doi = 10.1080/02541858.1995.11448385 |url = http://www.tandfonline.com/doi/pdf/10.1080/02541858.1995.11448385 }} {{open access}}</ref><ref>{{cite journal |last1 = Horak |first1 = I.G. |title = Parasites of domestic and wild animals in South Africa. XV. The seasonal prevalence of ectoparasites on impala and cattle in the Northern Transvaal |journal = The Onderstepoort Journal of Veterinary Research |date = 1982 |volume = 49 |issue = 2 |pages = 85–93 |pmid = 7177586 }}</ref> In Zimbabwe, heavy infestation by ticks such as ''R. appendiculatus'' has proved to be a major cause behind the high mortality of ungulates, as they can lead to [[tick paralysis]]. Impala have special adaptations for grooming, such as their characteristic dental arrangement, to manage ticks before they engorge; however, the extensive grooming needed to keep the tick load under control involves the risk of dehydration during summer, lower vigilance against predators and gradual wearing out of the teeth. A study showed that impala adjust the time devoted to grooming and the number of grooming bouts according to the seasonal prevalence of ticks.<ref name=Mooring1995 />
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=== Diet ===
=== Diet ===


[[File:AfricanSavanna-EmmenZoo.JPG|thumbnail|A herd grazing in [[Emmen Zoo]]]]
[[File:AfricanSavanna-EmmenZoo.JPG|thumbnail|alt=A herd grazing in Emmen Zoo|A herd grazing in [[Emmen Zoo]]]]


Impala [[browsing (herbivory)|browse]] as well as graze; either may predominate, depending upon the availability of resources.<ref name="Skinner">{{cite book |last1 = Skinner |first1 = J.D. |last2 = Chimimba |first2 = C.T. |title = The Mammals of the Southern African Subregion |date = 2005 |publisher = Cambridge University Press |location = Cambridge, UK |isbn = 978-0-521-84418-5 |pages = 703–8 |edition = 3rd }}</ref> The diet comprises [[monocot]]s, [[dicot]]s, [[forb]]s, fruits and ''[[Acacia]]'' pods (whenever available). Impala prefer places close to water sources, and resort to [[succulent plant|succulent vegetation]] if water is scarce.<ref name=estes /> An analysis showed that the diet of impala is composed of 45% monocots, 45% dicots and 10% fruits; the proportion of grasses in the diet increases significantly (to as high as 90%) after the first rains, but declines in the dry season.<ref>{{cite journal |last1 = Meissner |first1 = H.H. |last2 = Pieterse |first2 = E. |last3 = Potgieter |first3 = J.H.J. |title = Seasonal food selection and intake by male impala ''Aepyceros melampus'' in two habitats |journal = South African Journal of Wildlife Research |year = 1996 |volume = 26 |issue = 2 |pages = 56–63 |issn = 0379-4369 }}</ref> Browse predominates in the late wet and dry season, and diets are nutritionally poor in the mid-dry season, when impala feed mostly on woody dicots.<ref name="kingdon" /><ref>{{cite journal |last = Dunham |first = K. M. |title = The diet of Impala (''Aepyceros melampus'') in the Sengwa Wildlife Research Area, Rhodesia |journal = [[Journal of Zoology]] |date = 2009 |volume = 192 |issue = 1 |pages = 41–57 |doi = 10.1111/j.1469-7998.1980.tb04218.x }}</ref> Another study showed that the dicot proportion in the diet is much higher in bachelors and females than in territorial males.<ref>{{cite journal |last = van Rooyen |first = A.F. |last2 = Skinner |first2 = J.D. |title = Dietary differences between the sexes in impala |journal = Transactions of the Royal Society of South Africa |date = 1989 |volume = 47 |issue = 2 |pages = 181–5 |doi = 10.1080/00359198909520161 }}</ref>
Impala [[browsing (herbivory)|browse]] as well as graze; either may predominate, depending upon the availability of resources.<ref name="Skinner">{{cite book |last1 = Skinner |first1 = J.D. |last2 = Chimimba |first2 = C.T. |title = The Mammals of the Southern African Subregion |date = 2005 |publisher = Cambridge University Press |location = Cambridge, UK |isbn = 978-0-521-84418-5 |pages = 703–8 |edition = 3rd }}</ref> The diet comprises [[monocot]]s, [[dicot]]s, [[forb]]s, fruits and ''[[Acacia]]'' pods (whenever available). Impala prefer places close to water sources, and resort to [[succulent plant|succulent vegetation]] if water is scarce.<ref name=estes /> An analysis showed that the diet of impala is composed of 45% monocots, 45% dicots and 10% fruits; the proportion of grasses in the diet increases significantly (to as high as 90%) after the first rains, but declines in the dry season.<ref>{{cite journal |last1 = Meissner |first1 = H.H. |last2 = Pieterse |first2 = E. |last3 = Potgieter |first3 = J.H.J. |title = Seasonal food selection and intake by male impala ''Aepyceros melampus'' in two habitats |journal = South African Journal of Wildlife Research |year = 1996 |volume = 26 |issue = 2 |pages = 56–63 |issn = 0379-4369 }}</ref> Browse predominates in the late wet and dry season, and diets are nutritionally poor in the mid-dry season, when impala feed mostly on woody dicots.<ref name="kingdon" /><ref>{{cite journal |last = Dunham |first = K. M. |title = The diet of Impala (''Aepyceros melampus'') in the Sengwa Wildlife Research Area, Rhodesia |journal = [[Journal of Zoology]] |date = 2009 |volume = 192 |issue = 1 |pages = 41–57 |doi = 10.1111/j.1469-7998.1980.tb04218.x }}</ref> Another study showed that the dicot proportion in the diet is much higher in bachelors and females than in territorial males.<ref>{{cite journal |last = van Rooyen |first = A.F. |last2 = Skinner |first2 = J.D. |title = Dietary differences between the sexes in impala |journal = Transactions of the Royal Society of South Africa |date = 1989 |volume = 47 |issue = 2 |pages = 181–5 |doi = 10.1080/00359198909520161 }}</ref>
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=== Reproduction ===
=== Reproduction ===


[[File:Fighting impalas brighten.jpg|thumbnail|left|Two male impala fighting]]
[[File:Fighting impalas brighten.jpg|thumbnail|left|alt=Males lock horns in a mating fight|Two males fighting for [[dominance (ethology)|dominance]]]]


Males are [[sexually mature]] by the time they are a year old, though successful mating generally occurs only after four years. Mature males start establishing territories and try to gain access to females. Females can conceive after they are a year and a half old; [[oestrous]] lasts for 24 to 48 hours, and occurs every 12–29 days in non-pregnant females.<ref name="Nowak" /> The annual, three weeks-long rut (breeding season) begins toward the end of the wet season, typically in May. [[Gonad]]al growth and [[hormone]] production in males begin a few months before the breeding season, resulting in greater aggressiveness and territoriality;<ref name="estes" /> the [[bulbourethral gland]]s are heavier and [[testosterone]] levels nearly double in territorial males in comparison to bachelors.<ref>{{cite journal |last = Bramley |first = P.S. |last2 = Neaves |first2 = W.B. |title = The relationship between social status and reproductive activity in male impala, ''Aepyceros melampus'' |journal = [[Reproduction (journal)|Journal of Reproduction and Fertility]] |year = 1972 |volume = 31 |issue = 1 |pages = 77–81 |pmid = 5078117 |doi = 10.1530/jrf.0.0310077 }}</ref> Consequently, the neck of a territorial male tends to be thicker than that of a bachelor during the rut. Mating tends to take place between full moons, and might thus be influenced by the [[lunar cycle]].<ref name="estes" />
Males are [[sexually mature]] by the time they are a year old, though successful mating generally occurs only after four years. Mature males start establishing territories and try to gain access to females. Females can conceive after they are a year and a half old; [[oestrous]] lasts for 24 to 48 hours, and occurs every 12–29 days in non-pregnant females.<ref name="Nowak" /> The annual, three weeks-long rut (breeding season) begins toward the end of the wet season, typically in May. [[Gonad]]al growth and [[hormone]] production in males begin a few months before the breeding season, resulting in greater aggressiveness and territoriality;<ref name="estes" /> the [[bulbourethral gland]]s are heavier and [[testosterone]] levels nearly double in territorial males in comparison to bachelors.<ref>{{cite journal |last = Bramley |first = P.S. |last2 = Neaves |first2 = W.B. |title = The relationship between social status and reproductive activity in male impala, ''Aepyceros melampus'' |journal = [[Reproduction (journal)|Journal of Reproduction and Fertility]] |year = 1972 |volume = 31 |issue = 1 |pages = 77–81 |pmid = 5078117 |doi = 10.1530/jrf.0.0310077 }}</ref> Consequently, the neck of a territorial male tends to be thicker than that of a bachelor during the rut. Mating tends to take place between full moons, and might thus be influenced by the [[lunar cycle]].<ref name="estes" />
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== Distribution and habitat ==
== Distribution and habitat ==
[[File:Aepyceros melampus Impala in Tanzania 3490 Nevit.jpg|thumb|right|Impala inhabit woodlands.]]
[[File:Aepyceros melampus Impala in Tanzania 3490 Nevit.jpg|thumb|right|alt=A herd in Tanzania|Impala inhabit woodlands.]]
The impala inhabits woodlands due to its preference for shade; it can also occur on the interface ([[ecotone]]) between woodlands and [[savanna]]hs. Places close to water sources are preferred. In southern Africa, populations tend to be associated with ''[[Colophospermum mopane]]'' and ''Acacia'' woodlands.<ref name=estes /><ref name=Skinner /> Habitat choices differ seasonally{{snds}}''[[Acacia senegal]]'' woodlands are preferred in the wet season, and ''[[Acacia drepanolobium|A. drepanolobium]]'' savannahs in the dry season. Another factor that could influence habitat choice is vulnerability to predators; impala tend to keep away from areas with tall grasses as predators could be concealed there.<ref name=Sinclair>{{cite book |last1 = Jarman |first1 = P.J. |last2 = Sinclair |first2 = A.R.E. |editor1-last = Sinclair |editor1-first = A.R.E. |title = Serengeti, Dynamics of an Ecosystem |chapter = Feeding strategy and the pattern of resource partitioning in ungulates |year = 1984 |publisher = University of Chicago Press |location = Chicago, US |isbn = 978-0-226-76029-2 |pages = 130–63 |editor2-last = Norton-Griffths |editor2-first = M. }}</ref> A study found that the reduction of woodland cover and creation of shrublands by the [[African bush elephant]]s has favoured impala population by increasing the availability of more dry season browse. Earlier, the ''[[Baikiaea]]'' woodland, that has now declined due to elephants, provided minimum browse to impala. The newly formed ''[[Capparis]]'' shrubland, on the other hand, could be a key browsing habitat.<ref>{{cite journal |last = Rutina |first = L.P. |last2 = Moe |first2 = S.R. |last3 = Swenson |first3 = J.E. |title = Elephant ''Loxodonta africana'' driven woodland conversion to shrubland improves dry-season browse availability for impalas ''Aepyceros melampus'' |journal = Wildlife Biology |date = 2005 |volume = 11 |issue = 3 |pages = 207–13 |doi = 10.2981/0909-6396(2005)11[207:ELADWC]2.0.CO;2 |year = 2005 }}</ref> Impala are generally not associated with montane habitats;<ref name=kingdon /> however, in [[KwaZulu-Natal]], impala have been recorded at altitudes of up to {{convert|1,400|m|ft}} above the sea level.<ref name=Skinner />
The impala inhabits woodlands due to its preference for shade; it can also occur on the interface ([[ecotone]]) between woodlands and [[savanna]]hs. Places close to water sources are preferred. In southern Africa, populations tend to be associated with ''[[Colophospermum mopane]]'' and ''Acacia'' woodlands.<ref name=estes /><ref name=Skinner /> Habitat choices differ seasonally{{snds}}''[[Acacia senegal]]'' woodlands are preferred in the wet season, and ''[[Acacia drepanolobium|A. drepanolobium]]'' savannahs in the dry season. Another factor that could influence habitat choice is vulnerability to predators; impala tend to keep away from areas with tall grasses as predators could be concealed there.<ref name=Sinclair>{{cite book |last1 = Jarman |first1 = P.J. |last2 = Sinclair |first2 = A.R.E. |editor1-last = Sinclair |editor1-first = A.R.E. |title = Serengeti, Dynamics of an Ecosystem |chapter = Feeding strategy and the pattern of resource partitioning in ungulates |year = 1984 |publisher = University of Chicago Press |location = Chicago, US |isbn = 978-0-226-76029-2 |pages = 130–63 |editor2-last = Norton-Griffths |editor2-first = M. }}</ref> A study found that the reduction of woodland cover and creation of shrublands by the [[African bush elephant]]s has favoured impala population by increasing the availability of more dry season browse. Earlier, the ''[[Baikiaea]]'' woodland, that has now declined due to elephants, provided minimum browse to impala. The newly formed ''[[Capparis]]'' shrubland, on the other hand, could be a key browsing habitat.<ref>{{cite journal |last = Rutina |first = L.P. |last2 = Moe |first2 = S.R. |last3 = Swenson |first3 = J.E. |title = Elephant ''Loxodonta africana'' driven woodland conversion to shrubland improves dry-season browse availability for impalas ''Aepyceros melampus'' |journal = Wildlife Biology |date = 2005 |volume = 11 |issue = 3 |pages = 207–13 |doi = 10.2981/0909-6396(2005)11[207:ELADWC]2.0.CO;2 |year = 2005 }}</ref> Impala are generally not associated with montane habitats;<ref name=kingdon /> however, in [[KwaZulu-Natal]], impala have been recorded at altitudes of up to {{convert|1,400|m|ft}} above the sea level.<ref name=Skinner />


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== Threats and conservation ==
== Threats and conservation ==


[[File:Aepyceros melampus petersi female 8014.jpg|thumbnail|A group of black-faced impala introduced into the Etosha National Park]]
[[File:Aepyceros melampus petersi female 8014.jpg|thumbnail|alt=A group of black-faced impala introduced into the Etosha National Park|A group of black-faced impala introduced into the Etosha National Park]]


The International Union for Conservation of Nature and Natural Resources ([[IUCN]]) classifies the impala as [[Least Concern]];<ref name=iucn /> the black-faced impala, however, is classified as [[Vulnerable species|Vulnerable]] because, as of 2008, less than 1,000 individuals are estimated in the wild.<ref name=iucn2>{{IUCN2014.3|assessors=IUCN SSC Antelope Specialist Group |year=2008|id=549|title=Aepyceros melampus petersi|downloaded=9 May 2016}}</ref> Though there are no major threats to the survival of the common impala, poaching and natural calamities have significantly contributed to the decline of the black-faced impala. As of 2008, the population of the common impala has been estimated at around two million.<ref name=iucn /> Studies opine that [[Species translocation|translocation]] of the black-faced impala can be highly beneficial in its conservation.<ref name=green>{{cite journal |last = Green |first = W.C.H. |last2 = Rothstein |first2 = A. |title = Translocation, hybridisation, and the endangered black-faced impala |journal = [[Conservation Biology (journal)|Conservation Biology]] |year = 2008 |volume = 12 |issue = 2 |pages = 475–80 |doi = 10.1111/j.1523-1739.1998.96424.x }}</ref><ref name=matson>{{cite journal |last = Matson |first = T. |last2 = Goldizen |first2 = A.W. |last3 = Jarman |first3 = P.J. |title = Factors affecting the success of translocations of the black-faced impala in Namibia |journal = [[Biological Conservation (journal)|Biological Conservation]] |date = 2004 |volume = 116 |issue = 3 |pages = 359–65 |doi = 10.1016/S0006-3207(03)00229-5 }}</ref>
The International Union for Conservation of Nature and Natural Resources ([[IUCN]]) classifies the impala as [[Least Concern]];<ref name=iucn /> the black-faced impala, however, is classified as [[Vulnerable species|Vulnerable]] because, as of 2008, less than 1,000 individuals are estimated in the wild.<ref name=iucn2>{{IUCN2014.3|assessors=IUCN SSC Antelope Specialist Group |year=2008|id=549|title=Aepyceros melampus petersi|downloaded=9 May 2016}}</ref> Though there are no major threats to the survival of the common impala, poaching and natural calamities have significantly contributed to the decline of the black-faced impala. As of 2008, the population of the common impala has been estimated at around two million.<ref name=iucn /> Studies opine that [[Species translocation|translocation]] of the black-faced impala can be highly beneficial in its conservation.<ref name=green>{{cite journal |last = Green |first = W.C.H. |last2 = Rothstein |first2 = A. |title = Translocation, hybridisation, and the endangered black-faced impala |journal = [[Conservation Biology (journal)|Conservation Biology]] |year = 2008 |volume = 12 |issue = 2 |pages = 475–80 |doi = 10.1111/j.1523-1739.1998.96424.x }}</ref><ref name=matson>{{cite journal |last = Matson |first = T. |last2 = Goldizen |first2 = A.W. |last3 = Jarman |first3 = P.J. |title = Factors affecting the success of translocations of the black-faced impala in Namibia |journal = [[Biological Conservation (journal)|Biological Conservation]] |date = 2004 |volume = 116 |issue = 3 |pages = 359–65 |doi = 10.1016/S0006-3207(03)00229-5 }}</ref>

Revision as of 01:13, 30 May 2016

"Aepyceros" redirects here. For the extinct species, see Aepyceros datoadeni. For other uses, see Impala (disambiguation).

Impala
Male in the Serengeti
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Mammalia
Order:
Artiodactyla
Family:
Bovidae
Subfamily:
Aepycerotinae

Gray, 1872
Genus:
Aepyceros

Sundevall, 1847
Species:
A. melampus
Binomial name
Aepyceros melampus
(Lichtenstein, 1812)
Subspecies
  • A. m. me lampus Lichtenstein, 1812
  • A. m. petersi Bocage, 1879
Range of the impala
Synonyms[2]
List
  • A. holubi Lorenz, 1894
  • A. johnstoni Thomas, 1893
  • A. katangae Lönnberg, 1914
  • A. pallah (Gervais, 1841)
  • A. rendilis Lönnberg, 1912
  • A. typicus Thomas, 1893

The impala (pronounced /im-ˈpa-lə, -ˈpä-/) (Aepyceros melampus) is a medium-sized antelope that occurs in eastern and southern Africa. The sole member of the genus Aepyceros, it was first described by German zoologist Martin Hinrich Carl Lichtenstein in 1812. Two subspecies are recognised. The impala reaches 70–92 centimetres (28–36 inches) at the shoulder and weighs 40–76 kilograms (88–168 pounds). The antelope features a glossy, reddish brown coat. The slender, lyre-shaped horns, only on males, are 45–92 centimetres (18–36 in) long.

Active mainly during the day, the impala may be gregarious or territorial depending upon the climate and geography. Three distinct social groups can be observed – the territorial males, bachelor herds and female herds. The impala is known for its two characteristic leaps that constitute an anti-predator strategy – one in which it can jump up to 3 metres (9.8 feet), covering distances of up to 10 metres (33 ft); and another that involves a series of jumps in which the animal lands on its forelegs, moves its hindlegs mid-air in a kicking fashion, lands on all fours and then rebounds. Browsers as well as grazers, impala feed on monocots, dicots, forbs, fruits and Acacia pods (whenever available). An annual, three weeks-long rut toward the end of the wet season, typically in May. Rutting males fight over dominance, and the victorious male starts an elaborate courtship with the female in oestrus. Gestation lasts six to seven months, following which a single calf is born and immediately concealed in cover. Calves are suckled for four to six months; young males are forced out of the group and subsequently join bachelor herds, while females may stay back.

The impala occurs in woodlands and sometimes on the interface (ecotone) between woodlands and savannahs; it inhabits places close to water sources. While the black-faced impala is confined to southwestern Angola and Kaokoland in northwestern Namibia, the common impala is widespread across its range and has been reintroduced in Gabon and southern Africa. The IUCN classifies the impala as Least Concern; the black-faced subspecies, however, has been classified as Vulnerable because, as of 2008, less than 1,000 individuals remain in the wild.

Etymology

The common name "impala" (pronounced /im-ˈpa-lə, -ˈpä-/) comes from the Zulu name for the animal; the first recorded use of the name dates back to 1885.[3] An alternative name for the impala is "rooibok".[4] The scientific name of the impala is Aepyceros melampus; aepyceros comes from the Greek words αιπος aipos ("high") and κερος ceros ("horn").[5][6] The specific epithet melampus derives from the Greek words μελάς melas ("black") and πούς pous ("foot").[7]

Taxonomy and evolution

A female black-faced impala
The black-faced impala, a subspecies of the impala

The impala is the sole member of the genus Aepyceros and belongs to the family Bovidae. It was first described by German zoologist Martin Hinrich Carl Lichtenstein in 1812.[2] In 1845, Swedish zoologist Carl Jakob Sundevall placed the springbok in Antidorcas, a genus of its own.[8]

The impala's resemblance to the hartebeest led palaeontologist Elisabeth Vrba to consider the impala a sister taxon to the alcelaphines.[9] A 1999 phylogenetic study by Alexandre Hassanin (of the National Centre for Scientific Research, Paris) and colleagues, based on mitochondrial and nuclear analyses, showed that the impala forms a clade with the suni (Neotragus moschatus). This clade is sister to another formed by the bay duiker (Cephalophus dorsalis) and the klipspringer (Oreotragus oreotragus).[10] An rRNA and β-spectrin nuclear sequence analysis in 2003 also supported an association between Aepyceros and Neotragus.[11] The following cladogram is based on the 1999 study:[10]

Up to six subspecies have been described, although only two are generally recognised on the basis of mtDNA data.[12] Though morphologically similar,[13] the subspecies show a significant genetic distance between them, and no hybrids between them have been reported.[13][14]

  • A. m. melampus Lichtenstein, 1812: Known as the common impala. Occurs across eastern and southern Africa. The range extends from central Kenya to South Africa and westward into southeastern Angola.
  • A. m. petersi Bocage, 1879: Known as the black-faced impala. Restricted to southwestern Africa, it occurs in northwestern Namibia and southwestern Angola.

According to Vrba, the impala evolved from an alcelaphine ancestor. She noted that while this ancestor has diverged at least 18 times into various morphologically different forms, the impala has continued in its basic form for at least five million years.[9][15] Several fossil species have been discovered, including A. datoadeni from the Pliocene of Ethiopia.[16] The oldest fossil discovered suggests its ancient ancestors were slightly smaller than the modern form, but otherwise similar in all aspects to the latter. This implies that the impala has efficiently adapted to its environment since prehistoric times. Its gregarious nature, variety in diet, positive population trend, defence against ticks and symbiotic relationship with the tick-feeding oxpeckers could have played a role in preventing major changes in morphology and behaviour.[9]

Description

A grooming male at Serengeti National Park
Close view of a male. Note the lyre-shaped horns, white tail and several black markings.

The impala is a medium-sized, slender antelope similar to the kob or Grant's gazelle in build.[17] The head-and-body length is around 130 centimetres (51 in).[4] Males reach approximately 75–92 centimetres (30–36 in) at the shoulder, while females are 70–85 centimetres (28–33 in) tall. Males typically weigh 53–76 kilograms (117–168 lb) and females 40–53 kilograms (88–117 lb). Sexually dimorphic, females are hornless and notably smaller than males. Males grow 45–92 centimetres (18–36 in) long, slender, lyre-shaped horns.[17] The horns, strongly ridged and divergent, circular in section and hollow at the base. Their arch-like structure allows interlocking of horns, which helps a male throw off his opponent during fights; horns also protect the skull from damage.[13][17]

The glossy coat of the impala shows two-tone colouration – the reddish brown back and the tan flanks; these are in sharp contrast to the white underbelly. Facial features include white rings around the eyes and a light chin and snout. The ears, 1.7 centimetres (0.67 in) long, are tipped with black.[13][18] Black streaks run from the buttocks to the upper hindlegs. The bushy white tail, 30 centimetres (12 in) long, features a solid black stripe along the midline.[18] The impala has a strong resemblance to the gerenuk in terms of colouration; however, the gerenuk has shorter horns and lacks the black thigh stripes of the impala.[13] The impala has scent glands covered by the black tuft of hair on the hindlegs. Sebaceous glands are concentrated on the forehead and dispersed on the torso of dominant males;[17][19] these glands males are most active during the mating season, while those of females are only partially developed and do not undergo seasonal changes.[20] There are four nipples.[17]

Of the subspecies, the black-faced impala is significantly larger and darker than the common impala; a recessive gene is responsible for the black colouration.[21] Distinctive of the black-faced impala is the dark stripe on either side of the nose, that runs upward to the eyes and thins as it reaches the forehead.[4][18] Other differences include the larger black tip on the ear, and a bushier and nearly 30% longer tail in the black-faced impala.[13]

The impala has a special dental arrangement on the front lower jaw similar to the toothcomb seen in strepsirrhine primates,[22] which is used during allogrooming to comb the fur on the head and the neck and remove ectoparasites.[13][23]

Ecology and behaviour

An impala mid-air during a leap
Impala can leap up to 3 metres (9.8 ft).

The impala is diurnal (active mainly during the day), though activity tends to cease during the hot midday hours; the night is spent in feeding and resting.[17] Three distinct social groups can be observed – the territorial males, bachelor herds and female herds.[24] The territorial males hold territories where they may form harems of females; territories are demarcated with urine and faeces and defended against juvenile or male intruders.[17] Bachelor herds tend to be small, with less than 30 members. Individuals maintain distances of 2.5–3 metres (8.2–9.8 ft) from one another; while young and old males may interact, middle-aged males generally avoid one another. The membership of female herds varies from 6 to 100; herds occupy 80–180 hectares (200–440 acres; 0.31–0.69 sq mi) large home ranges. The mother-calf bond is weak, and breaks soon after weaning; juveniles leave the herds of their mothers to join other herds. Female herds tend to be loose and have no distinct leadership.[17][25] Allogrooming is an important means of social interaction in bachelor and female herds; in fact, the impala appears to be the only ungulate to display self-grooming as well as allogrooming. In allogrooming, females typically groom related individuals, while males associate with unrelated individuals. Each partner grooms the other six to twelve times.[26]

Social behaviour is influenced by the climate and geography; as such, the impala are territorial at certain times of the year and gregarious at other times, and the length of these periods can vary broadly among populations. For instance, populations in southern Africa display territorial behaviour only during the rut, that lasts a few months, and are otherwise gregarious; whereas in eastern African populations, territoriality is relatively minimal despite a protracted mating season. Moreover, territorial males often tolerate bachelors, and may even alternate between bachelorhood and territoriality at different times of the year. A study of impala in the Serengeti National Park showed that in 94% of the males, territoriality was observed only for a duration of less than four months.[17]

The impala is an important prey for several carnivores, such as cheetahs, leopards and lions. The impala displays two characteristic leaps – it can jump up to 3 metres (9.8 ft), over vegetation and even other impala, covering distances of up to 10 metres (33 ft); the other type of leap involves a series of jumps in which the animal lands on its forelegs, moves its hindlegs mid-air in a kicking fashion, lands on all fours and then rebounds. It leaps in either manner in different directions, probably to confuse predators.[13][27] At times, the impala may also conceal itself in vegetation to escape the eye of the predator.[28] The most prominent vocalisation is the loud roar, delivered through one to three loud snorts with the mouth closed, followed by two to ten deep grunts with the mouth open, the chin and the tail raised; a typical roar can be heard up to a distance of 2 kilometres (1.2 mi).[17] Scent gland secretions identify a territorial male.[29] A notable feature of impala is their sedentary nature; adult and middle-aged males, in particular, can hold their territories for years.[17]

Parasites

Red-billed oxpeckers feeding on parasites on a male
Impala have a symbiotic relationship with oxpeckers

Common ixodid ticks collected from impala include Amblyomma hebraeum, Boophilus decoloratus, Hyalomma marginatum, Ixodes cavipalpus, Rhipicephalus appendiculatus and R. evertsi.[30][31][32] In Zimbabwe, heavy infestation by ticks such as R. appendiculatus has proved to be a major cause behind the high mortality of ungulates, as they can lead to tick paralysis. Impala have special adaptations for grooming, such as their characteristic dental arrangement, to manage ticks before they engorge; however, the extensive grooming needed to keep the tick load under control involves the risk of dehydration during summer, lower vigilance against predators and gradual wearing out of the teeth. A study showed that impala adjust the time devoted to grooming and the number of grooming bouts according to the seasonal prevalence of ticks.[30]

Impala are symbiotically related to oxpeckers, that feed on ticks from those parts of the antelope's body which the animal cannot access by itself (such as the ears, neck, eyelids, forehead and underbelly). The impala is the smallest ungulate that oxpeckers are associated with. In a study it was observed that oxpeckers selectively attended to impala despite the presence of other animals such as Coke's hartebeest, Grant's gazelle, Thompson's gazelle and topi. A possible explanation for this could be that because the impala inhabits woodlands, that are considered to have a high density of ticks, unlike the other animals in the study that inhabit grasslands, the impala could have greater mass of ticks per unit area of the body surface.[33] Another study showed that the oxpeckers prefer the ears over other parts of the body, probably because these parts show maximum tick infestation.[34]

Lice recorded from impala include Damalinia aepycerus, D. elongata, Linognathus aepycerus and L. nevilli; in a study, ivermectin was found to have an effect on Boophilus decoloratus and Linognathus species, though not on Damalinia species.[35] In a study of impala in South Africa, the number of worms in juveniles showed an increase with age, reaching a peak when impala turned a year old. This study recorded worms of genera such as Cooperia, Cooperoides, Fasciola, Gongylonema. Haemonchus, Impalaia, Longistrongylus and Trichostrongylus; some of these showed seasonal variations in density.[36]

Diet

A herd grazing in Emmen Zoo
A herd grazing in Emmen Zoo

Impala browse as well as graze; either may predominate, depending upon the availability of resources.[37] The diet comprises monocots, dicots, forbs, fruits and Acacia pods (whenever available). Impala prefer places close to water sources, and resort to succulent vegetation if water is scarce.[17] An analysis showed that the diet of impala is composed of 45% monocots, 45% dicots and 10% fruits; the proportion of grasses in the diet increases significantly (to as high as 90%) after the first rains, but declines in the dry season.[38] Browse predominates in the late wet and dry season, and diets are nutritionally poor in the mid-dry season, when impala feed mostly on woody dicots.[13][39] Another study showed that the dicot proportion in the diet is much higher in bachelors and females than in territorial males.[40]

Impala carefully feed on soft and nutritious grasses such as Digitaria macroblephora; tough, tall grasses, such as Heteropogon contortus and Themeda triandra, are typically avoided.[41] Impala on the periphery of the herds are generally more vigilant against predators than those feeding in the centre; a foraging impala will try to defend the patch it is feeding on by lowering its head.[42] A study revealed that time spent in foraging reaches a maximum of 75.5% in the late dry season, decreases through the rainy season, and is minimal in the early dry season (57.8%).[43]

Reproduction

Males lock horns in a mating fight
Two males fighting for dominance

Males are sexually mature by the time they are a year old, though successful mating generally occurs only after four years. Mature males start establishing territories and try to gain access to females. Females can conceive after they are a year and a half old; oestrous lasts for 24 to 48 hours, and occurs every 12–29 days in non-pregnant females.[28] The annual, three weeks-long rut (breeding season) begins toward the end of the wet season, typically in May. Gonadal growth and hormone production in males begin a few months before the breeding season, resulting in greater aggressiveness and territoriality;[17] the bulbourethral glands are heavier and testosterone levels nearly double in territorial males in comparison to bachelors.[44] Consequently, the neck of a territorial male tends to be thicker than that of a bachelor during the rut. Mating tends to take place between full moons, and might thus be influenced by the lunar cycle.[17]

Rutting males fight over dominance, often giving out noisy roars and chasing one another; they walk stiffly and display their neck and horns. Males desist from feeding and allogrooming during the rut, probably to devote more time in garnering females in oestrus; the male checks the female's urine to ensure that she in oestrus.[45] On coming across such female, the excited male begins the courtship by pursuing her, keeping a distance of 3–5 metres (9.8–16.4 ft) from her. The male flicks his tongue and may nod vigorously; the female allows him to lick her vulva, and holds her tail to one side. The male tries mounting the female, holding his head high and clasping her sides with his forelegs. Mounting attempts may be repeated every few seconds to every minute or two. The male loses interest in the female after the first copulation, though she is still active and can mate with other males.[17][24]

Gestation lasts six to seven months; the mother may even delay giving birth for an additional month if conditions are harsh. Births generally occur in the midday; the female will isolate herself from the herd when labour pain begins.[46] A single calf is born, and is immediately concealed in cover for the first few weeks of its birth. The fawn then joins a nursery group within his mother's herd. Calves are suckled for four to six months; young males are forced out of the group and subsequently join bachelor herds, while females may stay back.[17]

Distribution and habitat

A herd in Tanzania
Impala inhabit woodlands.

The impala inhabits woodlands due to its preference for shade; it can also occur on the interface (ecotone) between woodlands and savannahs. Places close to water sources are preferred. In southern Africa, populations tend to be associated with Colophospermum mopane and Acacia woodlands.[17][37] Habitat choices differ seasonally – Acacia senegal woodlands are preferred in the wet season, and A. drepanolobium savannahs in the dry season. Another factor that could influence habitat choice is vulnerability to predators; impala tend to keep away from areas with tall grasses as predators could be concealed there.[41] A study found that the reduction of woodland cover and creation of shrublands by the African bush elephants has favoured impala population by increasing the availability of more dry season browse. Earlier, the Baikiaea woodland, that has now declined due to elephants, provided minimum browse to impala. The newly formed Capparis shrubland, on the other hand, could be a key browsing habitat.[47] Impala are generally not associated with montane habitats;[13] however, in KwaZulu-Natal, impala have been recorded at altitudes of up to 1,400 metres (4,600 ft) above the sea level.[37]

The historical range of the impala, that spanned across southern and eastern Africa, has remained intact to a great extent, although the antelope has disappeared from a few places such as Burundi. The range extends from central and southern Kenya and northeastern Uganda in the east to northern KwaZulu-Natal in the south, and westward up to Namibia and southern Angola. The black-faced impala is confined to southwestern Angola and Kaokoland in northwestern Namibia; the status of this subspecies has not been monitored since the 2000s. The common impala has a wider distribution, and has been introduced in protected areas in Gabon and across southern Africa.[1]

Threats and conservation

A group of black-faced impala introduced into the Etosha National Park
A group of black-faced impala introduced into the Etosha National Park

The International Union for Conservation of Nature and Natural Resources (IUCN) classifies the impala as Least Concern;[1] the black-faced impala, however, is classified as Vulnerable because, as of 2008, less than 1,000 individuals are estimated in the wild.[48] Though there are no major threats to the survival of the common impala, poaching and natural calamities have significantly contributed to the decline of the black-faced impala. As of 2008, the population of the common impala has been estimated at around two million.[1] Studies opine that translocation of the black-faced impala can be highly beneficial in its conservation.[49][50]

Around a quarter of the common impala populations occur in protected areas, such as the Okavango Delta (Botswana); Masai Mara and Kajiado (Kenya); Kruger National Park (South Africa); the Ruaha and Serengeti National Parks and Selous Game Reserve (Tanzania); Luangwa Valley (Zambia); Hwange, Sebungwe and Zambezi Valley (Zimbabwe). The rare black-faced impala has been introduced into private farms in Namibia and the Etosha National Park. Population densities vary largely from place to place; from less than one individual per square kilometre in Mkomazi National Park (Tanzania) to as high as 135 individuals per square kilometre near Lake Kariba (Zimbabwe).[1][51]

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