Editing Impala (section)

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

The impala is [[Diurnality|diurnal]] (active mainly during the day), though activity tends to cease during the hot midday hours; they feed and rest at night.<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 |bibcode = 1966AfJEc...4...99S }}</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 {{cvt|2.5|-|3|m|ft}} from one another; while young and old males may interact, middle-aged males generally avoid one another except to spar. Female herds vary in size from 6 to 100; herds occupy [[home range]]s of {{cvt|80|-|180|ha|acre sqmi}}. 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 obvious 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|bibcode = 1981BEcoS...9...23M |s2cid = 24117010 }}</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 impalas, while males associate with unrelated ones. 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 = 1073–1083 |doi = 10.1016/S0003-3472(05)80319-7 |s2cid = 53165208 }}</ref>
[[File:Impala-stotting.jpg|thumb|left|An impala [[stotting]]]]
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 few months of the [[Rut (mammalian reproduction)|rut]], 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 for less than four months.<ref name=estes />

The impala is an important prey species for Africa's large [[carnivore]]s, such as [[cheetah]]s, [[leopard]]s, [[African wild dog|wild dogs]], [[lion]]s, [[Spotted hyena|hyenas]], [[nile crocodile|crocodiles]] and [[Southern African rock python|pythons]]. The antelope displays two characteristic leaps{{snds}}it can jump up to {{cvt|3|m|ft}}, over vegetation and even other impala, covering distances of up to {{cvt|10|m|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 ([[stotting]]) and then rebounds. It leaps in either manner in different directions, probably to confuse [[predator]]s.<ref name=kingdon /><ref>{{cite web|url = http://animals.nationalgeographic.com/animals/mammals/impala/ |archive-url = https://web.archive.org/web/20100207175127/http://animals.nationalgeographic.com/animals/mammals/impala/ |url-status = dead |archive-date = 7 February 2010 |title = Impala: ''Aepyceros melampus'' |date = 11 April 2010 |publisher = [[National Geographic Society|National Geographic]] |access-date = 6 May 2014}}</ref> At times, the impala may also conceal itself in vegetation to escape the eye of the predator.<ref name=Nowak>{{cite book |last = Nowak |first = R.M. |title = Walker's Mammals of the World |volume= 2 |year = 1999 |publisher = Johns Hopkins University Press |location = Baltimore, USA |isbn = 978-0-8018-5789-8 |pages = 1194–6 |edition = 6th |oclc = 39045218}}</ref> 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 and the chin and tail raised; a typical roar can be heard up to {{cvt|2|km|mi}} away.<ref name=estes /> Scent gland secretions identify a territorial male.<ref name="Kingdon1989">{{cite book|last1 = Kingdon |first1 = J. |author-link = Jonathan Kingdon |title = East African Mammals: An Atlas of Evolution in Africa |volume = 3 |date = 1989 |publisher = Academic Press |location = London, UK |isbn = 978-0-226-43725-5 |pages = 462–74 |url = {{Google Books|id=JiHqC9ROZTQC|page=462|plainurl=yes}} |oclc = 48864096}}</ref> Impalas are sedentary; adult and middle-aged males, in particular, can hold their territories for years.<ref name="estes" />

===Parasites===
[[File:Red-billed oxpecker (Buphagus erythrorhynchus) on impala (Aepyceros melampus).jpg|thumb|Impala have a symbiotic relationship with [[oxpecker]]s]]

Common [[Ixodidae|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 |date = 1995 |volume = 50 |issue = 2 |pages = 377–92 |doi = 10.1006/anbe.1995.0253 |s2cid = 53185353 |url = http://www.pointloma.edu/sites/default/files/filemanager/Biology/Faculty/Mooring/Publications/1995-Tick_challenge_impala_grooming_Anim_Behav.pdf |url-status = dead |archive-url = https://web.archive.org/web/20161012005200/http://www.pointloma.edu/sites/default/files/filemanager/Biology/Faculty/Mooring/Publications/1995-Tick_challenge_impala_grooming_Anim_Behav.pdf |archive-date = 12 October 2016 |df = dmy-all }}</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 |doi-access = free }} {{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 [[Wildlife of Zimbabwe|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 />

Impala are symbiotically related to [[oxpecker]]s,<ref>Mikula P, Hadrava J, Albrecht T, Tryjanowski P. (2018) Large-scale assessment of commensalistic–mutualistic associations between African birds and herbivorous mammals using internet photos. PeerJ 6:e4520 https://doi.org/10.7717/peerj.4520</ref> which 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 with which oxpeckers are associated. 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, [[Thomson's gazelle]] and [[topi]]. A possible explanation for this could be that because the impala inhabits woodlands (which can have a high density of ticks), the impala could have greater mass of ticks per unit area of the body surface.<ref>{{cite journal |last1 = Hart |first1 = B.L. |last2 = Hart |first2 = L.A. |last3 = Mooring |first3 = M.S. |title = Differential foraging of oxpeckers on impala in comparison with sympatric antelope species |journal = African Journal of Ecology |date = 1990 |volume = 28 |issue = 3 |pages = 240–9 |doi = 10.1111/j.1365-2028.1990.tb01157.x |bibcode = 1990AfJEc..28..240H |url = https://www.researchgate.net/publication/229520029 }} {{open access}}</ref> Another study showed that the oxpeckers prefer the ears over other parts of the body, probably because these parts show maximum tick infestation.<ref>{{cite journal |last1 = Mooring |first1 = M.S. |last2 = Mundy |first2 = P.J. |title = Interactions between impala and oxpeckers at Matobo National Park, Zimbabwe |journal = African Journal of Ecology |date = 1996 |volume = 34 |issue = 1 |pages = 54–65 |doi = 10.1111/j.1365-2028.1996.tb00594.x |bibcode = 1996AfJEc..34...54M |url = https://www.researchgate.net/publication/227814876 }} {{open access}}</ref> The bird has also been observed to perch on the [[udders]] of a female and pilfer its [[milk]].<ref>{{cite journal |last1=Hussain Kanchwala |title=How Did We Start Drinking Milk Of The Ruminants? Are We The Only Species To Drink Milk Of Other Species? |journal=ScienceABC |date=2022 |url=https://www.scienceabc.com/humans/species-drink-milk-another-species.html}}</ref>

[[Louse|Lice]] recorded from impala include ''[[Damalinia aepycerus]]'', ''[[Damalinia elongata|D. elongata]]'', ''[[Linognathus aepycerus]]'' and ''[[Linognathus nevilli|L. nevilli]]''; in a study, [[ivermectin]] (a medication against parasites) was found to have an effect on ''Boophilus decoloratus'' and ''Linognathus'' species, though not on ''Damalinia'' species.<ref>{{cite journal |last1 = Horak |first1 = I.G. |last2 = Boomker |first2 = J. |last3 = Kingsley |first3 = S.A. |last4 = De Vos |first4 = V. |title = The efficacy of ivermectin against helminth and arthropod parasites of impala |journal = Journal of the South African Veterinary Association |date = 1983 |volume = 54 |issue = 4 |pages = 251–3 |pmid = 6689430 }}</ref> In a study of impala in South Africa, the number of [[worm]]s 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 (nematode)|Cooperia]]'', ''[[Cooperoides]]'', ''[[Fasciola]]'', ''[[Gongylonema]]''. ''[[Haemonchus]]'', ''[[Impalaia]]'', ''[[Longistrongylus]]'' and ''[[Trichostrongylus]]''; some of these showed seasonal variations in density.<ref>{{cite journal |last1 = Horak |first1 = I.G. |title = Parasites of domestic and wild animals in South Africa. X. Helminths in impala |journal = The Onderstepoort Journal of Veterinary Research |date = 1978 |volume = 45 |issue = 4 |pages = 221–8 |pmid = 572950 }}</ref>

Impala show high frequency of [[defensive behaviour]]s towards flying insects.<ref name="Auty-et-al-2016">{{cite journal | last1=Auty | first1=Harriet | last2=Morrison | first2=Liam J. | last3=Torr | first3=Stephen J. | last4=Lord | first4=Jennifer | title=Transmission Dynamics of Rhodesian Sleeping Sickness at the Interface of Wildlife and Livestock Areas | journal=[[Trends in Parasitology]] | publisher=[[Cell Press]] | volume=32 | issue=8 | year=2016 | issn=1471-4922 | doi=10.1016/j.pt.2016.05.003 | pages=608–621| pmid=27262917 | url=http://eprints.gla.ac.uk/215396/1/215396.pdf }}</ref> This is probably the reason for Vale 1977 and Clausen et al 1998 only finding [[trace levels]] of feeding by ''Glossina'' ([[tsetse fly]]) upon impala.<ref name="Auty-et-al-2016" />

''[[Theileria]]'' of impala in [[Kenya]] are not [[cross infection|cross infectious]] to [[cattle]]: Grootenhuis et al 1975 were not able to induce cattle infection and Fawcett et al 1987 did not find it naturally occurring.<ref name="Grootenhuis-Olubayo-1993">{{cite journal | last1=Grootenhuis | first1=J.G. | last2=Olubayo | first2=R.O. | title=Disease research in the wildlife-livestock interface in Kenya | journal=[[Veterinary Quarterly]] | publisher=[[Royal Netherlands Veterinary Association]]+[[Flemish Veterinary Association]] ([[Taylor & Francis|T&F]]) | volume=15 | issue=2 | year=1993 | issn=0165-2176 | doi=10.1080/01652176.1993.9694372 | pages=55–59| pmid=8372423 | doi-access=free }}</ref>

===Diet===
[[File:Aepyceros melampus (Masai Mara, Kenya).jpg|thumbnail|alt= |A herd grazing in [[Maasai Mara]]]]

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 |oclc = 62703884}}</ref> The diet comprises [[monocot]]s, [[dicot]]s, [[forb]]s, fruits and ''[[Acacieae|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> Browsing 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 |last1 = van Rooyen |first1 = 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 feed on soft and nutritious grasses such as ''[[Digitaria macroblephara]]''; tough, tall grasses, such as ''[[Heteropogon contortus]]'' and ''[[Themeda triandra]]'', are typically avoided.<ref name=Sinclair /> Impala on the periphery of the herds are generally more vigilant against predators than those feeding in the centre; a foraging individual will try to defend the patch it is feeding on by lowering its head.<ref>{{cite journal |last1 = Blanchard |first1 = P. |last2 = Sabatier |first2 = R. |last3 = Fritz |first3 = H. |title = Within-group spatial position and vigilance: a role also for competition? The case of impalas (''Aepyceros melampus'') with a controlled food supply |journal = Behavioral Ecology and Sociobiology |date = 2008 |volume = 62 |issue = 12 |pages = 1863–8 |doi = 10.1007/s00265-008-0615-3 |bibcode = 2008BEcoS..62.1863B |s2cid = 11796268 }}</ref> A study revealed that time spent in foraging reaches a maximum of 75.5% of the day in the late dry season, decreases through the rainy season, and is minimal in the early dry season (57.8%).<ref>{{cite journal |last = Wronski |first = T. |title = Feeding ecology and foraging behaviour of impala ''Aepyceros melampus'' in Lake Mburo National Park, Uganda |journal = [[African Journal of Ecology]] |date = September 2002 |volume = 40 |issue = 3 |pages = 205–11 |doi = 10.1046/j.1365-2028.2002.00348.x |bibcode = 2002AfJEc..40..205W }}</ref>

===Reproduction===
[[File:Fighting impalas brighten.jpg|thumbnail|alt=Males lock horns in a mating fight|Two males fighting for [[dominance (ethology)|dominance]]]]
Males are [[sexual maturity|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; [[oestrus]] lasts for 24 to 48 hours, and occurs every 12–29 days in non-pregnant females.<ref name="Nowak" /> The annual three-week-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, [[testosterone]] levels are nearly twice as high in territorial males as in bachelors,<ref>{{cite journal |last1 = Bramley |first1 = 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|url=http://www.reproduction-online.org/content/31/1/77.full.pdf|doi-access = free }}</ref> and 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.<ref name="estes" />
[[File:Impala (Aepyceros melampus) (W1CDR0000514 BD37).ogg|right|thumb|Sounds of rutting male]]
[[Rut (mammalian reproduction)|Rutting]] males fight over dominance, often giving out noisy roars and chasing one another; they walk stiffly and [[Display (zoology)|display]] their neck and horns. Males desist from feeding and allogrooming during the rut, probably to devote more time to garnering females in oestrus;<ref name=hart2/> the male checks the female's urine to ensure that she is in oestrus.<ref>Hart, Lynette A., and Benjamin L. Hart. "[https://www.researchgate.net/profile/Benjamin_Hart4/publication/232525532_Species-specific_patterns_of_urine_investigation_and_flehmen_in_Grant%27s_gazelle_Gazella_granti_Thomson%27s_gazelle_G_thomsoni_impala_Aepyceros_melampus_and_eland_Taurotragus_oryx/links/554522870cf24107d397b00d.pdf Species-specific patterns of urine investigation and flehmen in Grant's gazelle (Gazella granti), Thomson's gazelle (G. thomsoni), impala (Aepyceros melampus), and eland (Taurotragus oryx)]." Journal of Comparative Psychology 101.4 (1987): 299.</ref><ref name=hart2>{{cite journal |last = Mooring |first = M. S. |author2 = Hart, B. L. |title = Differential grooming rate and tick load of territorial male and female impala |journal = [[Behavioral Ecology (journal)|Behavioral Ecology]] |year = 1995 |volume = 6 |issue = 1 |pages = 94–101 |doi = 10.1093/beheco/6.1.94 }}</ref> On coming across such a female, the excited male begins the [[Courtship display|courtship]] by pursuing her, keeping a distance of {{convert|3|-|5|m|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.<ref name="estes" /><ref name="schenkel" />

Gestation lasts six to seven months. Births generally occur in the midday; the female will isolate herself from the herd when labour pain begins.<ref name=jarman>{{cite book |last = Jarman |first = M.V. |title = Impala Social Behaviour: Territory, Hierarchy, Mating, and the Use of Space |year = 1979 |publisher = Parey |location = Berlin, Germany |isbn = 978-3-489-60936-0 |pages = 1–92 |oclc = 5638565}}</ref> The perception that females can delay giving birth for an additional month if conditions are harsh may however not be realistic.<ref>{{cite web|url=http://blog.londolozi.com/2016/11/can-impala-really-delay-their-births|first=Shaun|last=D'Araujo|title=Can Impala Really Delay Their Births?|website=Londolozi Blog|date=20 November 2016}}</ref> 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 its mother's herd. Calves are suckled for four to six months; young males, forced out of the group, join bachelor herds, while females may stay back.<ref name="estes" />