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{{Short description|Species of antelope}}
{{About|the antelope}}
{{Good article}}
{{Speciesbox
| name = Nyala
| status = LC
| status_system = IUCN3.1
| status_ref = <ref name=iucn>{{cite iucn |author=IUCN SSC Antelope Specialist Group. |year=2016 |errata=2017 |title=''Tragelaphus angasii'' |volume=2016 |page=e.T22052A115165681 |doi=10.2305/IUCN.UK.2016-3.RLTS.T22052A50196443.en |access-date=1 May 2022}}</ref>
| image = Nyala (Tragelaphus angasii) male Maputo.jpg
| image_caption = Male
| image2 = Nyala-Female-Kruger-National-Park.jpg
| image2_caption = Female
| taxon = Tragelaphus angasii
| authority = ([[George French Angas|Angas]], 1849)
| range_map = Tragelaphus angasii distribution.svg
| range_map_caption = Geographic range
| synonyms_ref=<ref name=huffman/>
| synonyms=* ''Nyala angasii''
}}

The '''lowland nyala''' or simply '''nyala''' ('''''Tragelaphus angasii''''')<ref name=burton/> is a spiral-horned [[artiodactyl]] [[antelope]] native to [[Southern Africa]]. The species is part of the family [[Bovidae]] and the genus ''[[Tragelaphus]]'' (formerly placed in the genus ''Nyala''). It was first [[Species description|described]] in 1849 by [[George French Angas]] and exhibits the highest [[sexual dimorphism]] among the spiral-horned antelopes. It is not to be confused with the endangered [[mountain nyala]] living in the Bale region of Ethiopia.

The nyala's range encompasses much of [[Southern Africa]]. As its population is relatively stable, it has been listed as of [[least concern]] by the [[International Union for Conservation of Nature]]. It generally browses during the day in warm weather and during the night in the rainy season. As a herbivore, the nyala feeds upon foliage, fruits and grasses, and requires sufficient fresh water. A shy animal, it prefers water holes rather than open spaces. The nyala does not show signs of territoriality, and individuals' areas can overlap. They are very cautious creatures. 

They live in single-sex or mixed family groups of up to ten individuals, but old males live alone. They inhabit thickets within dense and dry savanna woodlands. The principal threats to the species are illegal poaching and habitat loss resulting from human settlement and livestock grazing. However, the large-horned, impressive males are highly prized as [[game (food)|game animals]] by sport hunters.

==Taxonomy and naming==
{{cladogram|align=left|title=
|caption=Phylogenetic relationships of the mountain nyala from combined analysis of all molecular data (Willows-Munro et.al. 2005)
|cladogram={{clade | style=font-size:90%;line-height:100%;width:300px;
|1={{clade
|1={{clade |label1=
 |1= {{clade|label1=
           |1=
         {{clade
         |label1=
         |1={{clade
            |1={{clade
                |1={{clade
                   |1=[[Giant eland]]
                   |2=[[Common eland]]}}
                |2={{clade
                   |1=[[Greater kudu]]
                   |2={{clade
                       |1=[[Mountain nyala]]
                       |2={{Clade
                           |1={{clade
                              |1={{clade
                                  |1=[[Bongo (antelope)|Bongo]]
                                  |2=[[Sitatunga]]}}
                           |2={{Clade
                           |1={{clade
                              |1={{clade
                                  |1=[[Cape bushbuck]]
|2=[[Harnessed bushbuck]] }} }} }} }} }} }} }} }} 
         |2='''Lowland nyala'''}}
|2=[[Lesser kudu]] }} }} }} }} }} }}
The nyala was first [[species description|described]] by [[George French Angas]], an English naturalist, in 1849. The [[scientific name]] of nyala is ''Tragelaphus angasii''. The name ''angasii'' is attributed to Angas, who said that [[John Edward Gray]] had named this species after Angas' father, [[George Fife Angas]] of South Australia. According to Article 50.1.1 of the [[International Code of Zoological Nomenclature]] and [[International Commission on Zoological Nomenclature]], though, this is insufficient to state Gray as the author.<ref name=MSW3/> The name "nyala" is the [[Tsonga language|Tsonga]] name for this antelope, which is likely the source of the English, along with [[Zulu language|Zulu]] {{Lang|zu|inyala}}.<ref>OED2</ref> Its first known use was in 1899. The word has a [[Bantu languages|Bantu]] origin, similar to the [[Venda language|Venda]] word {{Lang|ve|dzì-nyálà}} (nyala buck).<ref>{{Merriam-Webster|Nyala|access-date=30 January 2016}}</ref>

The nyala is the second [[taxon]] to branch off from the tragelaphine family tree just after the [[lesser kudu]]. As the nyala line has remained separate for a considerable time (over 5&nbsp;million years), some authorities have placed it in its own monotypic genus ''Nyala''. ''Nyala'' was proposed in 1912 by American zoologist [[Edmund Heller]], who also proposed ''Ammelaphus'' for the lesser kudu,<ref name=heller>{{cite book| author=Heller, E.| author-link=Edmund Heller| title=New Genera and Races of African Ungulates| publisher=Smithsonian Institution| location=Washington D. C.| url=https://www.biodiversitylibrary.org/pdf3/005508900035814.pdf| page=15| date= 2 November 1912}}</ref> but it was not widely recognized. It was re-erected as a valid genus in 2011 under the classification of [[Peter Grubb (zoologist)|Peter Grubb]] and [[Colin Groves]],<ref>{{cite book| last1=Groves|first1=C.| last2=Grubb|first2=P.| title=Ungulate Taxonomy| year=2011}}</ref> but has not been embraced by taxonomic authorities such as the Mammal Diversity Database.<ref name=burton>{{cite book| last=Burton| first=M.| title=International wildlife encyclopedia| year=2002| publisher=Marshall Cavendish| location=New York| isbn=978-0-7614-7269-8| author2=Burton, R.| edition=3rd| pages=1765–6| chapter=Nyala| chapter-url=https://archive.org/details/internationalwil03burt0}}</ref><ref>{{Cite web |title=Nyala |url=https://www.mammaldiversity.org/explore.html#genus=Tragelaphus&species=angasii&id=1006275 |access-date=7 August 2022 |website=Mammal Diversity Database}}</ref> Among its closest extant relatives are the forest-inhabiting [[Bongo (antelope)|bongo]], the [[Cape bushbuck|bushbuck]], the large [[Common eland|common]] and [[Giant eland|giant elands]], the [[Greater kudu|greater]] and [[Lesser kudu|lesser kudus]], the [[mountain nyala]] (of [[Ethiopia]]) and the swamp-dwelling [[sitatunga]], all of which share similar characteristics, such as hornless females, vertical side-stripes and other unique white markings, and the spiraling horns and distinct "beard" or [[dewlap]] of males, often with a raised trail of fur extending down the back and underside.{{cn|date=May 2024}}
[[File:ZOO Hellabrunn, München - kudui.jpg|thumb|Nyala family in captivity]]

In 2005, Sandi Willows-Munro (of the [[University of KwaZulu-Natal]]) and colleagues carried out a [[mitochondrial DNA]] analysis of the nine ''Tragelaphus'' species. Mitochondrial DNA and [[nDNA|nuclear DNA]] data were compared. The results showed the tribe Tragelaphini to be [[monophyletic]], with the [[lesser kudu]] (''T.&nbsp; imberbis'') [[Basal (phylogenetics)|basal]] in the phylogeny, followed by the nyala.<ref name=cladogram>{{cite journal|last1=Willows-Munro|first1=S.|last2=Robinson|first2=T. J.|last3=Matthee|first3=C. A.|title=Utility of nuclear DNA intron markers at lower taxonomic levels: Phylogenetic resolution among nine ''Tragelaphus'' spp.|journal=Molecular Phylogenetics and Evolution|date=June 2005|volume=35|issue=3|pages=624–36|doi=10.1016/j.ympev.2005.01.018|pmid=15878131|bibcode=2005MolPE..35..624W }}</ref><ref name="groves2014">{{cite journal|last1=Groves|first1=C.|title=Current taxonomy and diversity of crown ruminants above the species level|journal=Zitteliana|date=2014|volume=32|issue=B|pages=5–14|url=http://www.palmuc.de/bspg/images/pdf/zitteliana32/1_groves.pdf|issn=1612-4138|access-date=2016-03-22|archive-url=https://web.archive.org/web/20160204110133/http://www.palmuc.de/bspg/images/pdf/zitteliana32/1_groves.pdf|archive-date=2016-02-04|url-status=dead}}</ref> On the basis of mitochondrial data, studies have estimated that the lesser kudu separated from its [[sister clade]] around 13.7&nbsp;million years ago. However, nuclear DNA data shows lesser kudu and nyala forming a clade, which collectively separated from the sister clade 13.8&nbsp;million years ago.<ref name="ropiquet">{{cite thesis|last1=Ropiquet|first1=A.|title=Etude des radiations adaptatives au sein des Antilopinae (Mammalia, Bovidae)|degree=Ph.D. |publisher= Université Paris|year=2006|trans-title=Study of adaptative radiations within Antilopinae (Mammalia, Bovidae)|lang=fr}}</ref><ref name="hassanin">{{cite journal|last1=Hassanin|first1=A.|last2=Delsuc|first2=F.|last3=Ropiquet|first3=A.|last4=Hammer|first4=C.|last5=Jansen van Vuuren|first5=B.|last6=Matthee|first6=C.|last7=Ruiz-Garcia|first7=M.|last8=Catzeflis|first8=F.|last9=Areskoug|first9=V.|last10=Nguyen|first10=T.T.|last11=Couloux|first11=A.|title=Pattern and timing of diversification of Cetartiodactyla (Mammalia, Laurasiatheria), as revealed by a comprehensive analysis of mitochondrial genomes|journal=Comptes Rendus Biologies|date=2012|volume=335|issue=1|pages=32–50|doi=10.1016/j.crvi.2011.11.002|pmid=22226162|doi-access=free}}</ref>

===Genetics and evolution===
The nyala has 55 male [[chromosome]]s and 56 female chromosomes.<ref name=Rubes>{{cite journal| last=Rubes| first=J.|author2=Kubickova, S. |author3=Pagacova, E. |author4=Cernohorska, H. |author5=Berardino, D. |author6=Antoninova, M. |author7=Vahala, J. |author8= Robinson, T. J. | title=Phylogenomic study of spiral-horned antelope by cross-species chromosome painting| journal=Chromosome Research|year=2008| volume=16| issue=7| pages=935–47| doi=10.1007/s10577-008-1250-6| pmid=18704723| s2cid=23066105}}</ref> The [[Y chromosome]] has been [[Chromosomal translocation|translocated]] onto the 14th chromosome, as in other [[Tragelaphus|tragelaphids]], but no [[Chromosomal inversion|inversion]] of the Y chromosome occurs.<ref name=MSW3>{{MSW3 Artiodactyla | id = 14200727 | page = 126}}</ref> Cranial studies have shown that the [[mountain nyala]] and nyala, though sharing a common name, are actually distant relatives.<ref name=antelope/>

Fossil evidence suggests that the nyala has been a separate species since the end of the [[Miocene]] (5.8&nbsp;million years ago). Genetic evidence suggests that the proto-nyala had some early hybridization with the proto-lesser kudu, but the two have remained separate long after this crossing.<ref name=MSW3/>

==Physical description==
[[File:Nyalas male.jpg|thumb|left|Male in the Kruger National Park]]
The nyala is a spiral-horned and middle-sized antelope, between a [[Cape bushbuck|bushbuck]] and a [[kudu]].<ref name=unwin>{{cite book| last=Unwin| first=M.| title=Southern African Wildlife : A Visitor's Guide| year=2003| publisher=Bradt Travel Guides| location=Chalfont St. Peter| isbn=978-1-84162-060-2|page=78}}</ref> It is considered the most [[sexually dimorphic]] antelope.<ref name=huffman>{{cite web|last=Huffman|first=B.|title=Nyala|url=http://www.ultimateungulate.com/artiodactyla/Tragelaphus_angasii.html|publisher=Ultimate Ungulate}}</ref> The nyala is typically between {{cvt|135|–|195|cm}} in head-and-body length.<ref name=huffman/> The male stands up to {{cvt|110|cm|in}}, the female is up to {{cvt|90|cm|ft}} tall. Males weigh {{cvt|98|-|125|kg}}, while females weigh {{cvt|55|-|68|kg}}. Life expectancy of the nyala is about 19 years.<ref name=adw>{{cite web| last=Ciszek| first=D.| title=''Tragelaphus angasii''| url=http://animaldiversity.ummz.umich.edu/site/accounts/information/Tragelaphus_angasii.html| work=University of Michigan Museum of Zoology| publisher=Animal Diversity Web}}</ref>

The coat is rusty or [[rufous]] brown in females and juveniles. It grows a dark brown or slate grey in adult males, often with a bluish tinge.<ref name=huffman/> Females and young males have ten or more white vertical stripes on their sides. Other markings are visible on the face, throat, flanks and thighs. Stripes are very reduced or absent in older males. Both males and females have a white [[Chevron (anatomy)|chevron]] between their eyes, and a {{cvt|40|-|55|cm}} long bushy tail white underside. Both sexes have a dorsal crest of hair running right from the back of the head to the end of the tail. Males have another line of hair along the midline of their chest and belly.<ref name=adw/><ref name=estes>{{cite book| last=Estes| first=R. D.| title=The Safari Companion : A Guide to Watching African Mammals, Including Hoofed Mammals, Carnivores, and Primates| year=1999| publisher=Chelsea Green Pub. Co.| isbn=978-1-890132-44-6| edition=Revised| page=[https://archive.org/details/safaricompaniong00este_0/page/143 143]| chapter=Nyala| chapter-url=https://archive.org/details/safaricompaniong00este_0| url=https://archive.org/details/safaricompaniong00este_0/page/143}}</ref>

Only the males have horns. Horns are {{cvt|60|-|83|cm}} long and yellow-tipped. There are one or two twists.<ref name=huffman/> The [[spoor (animal)|spoor]] is similar to that of the bushbuck, but larger. It is {{cvt|5|-|6|cm}} long. The feces resemble round to spherical pellets.<ref name=walker>{{cite book| last=Walker| first=C.| title=Signs of the Wild| year=1996| publisher=Struik| isbn=978-1-86825-896-3| edition=5th |page=194| chapter=Nyala}}</ref> The nyala has hairy glands on its feet, which leave their scent wherever it walks.<ref name=burton/>

The condition of the nyala often varies between the sexes. According to a study, this can be attributed to the differences in their body sizes. It was noted that during nutritional stress, old adults died in more numbers, of which most were males.<ref>{{cite journal| last=Anderson| first=J. L.| title=Condition and related mortality of nyala (''Tragelaphus angasi'') in Zululand, South Africa| journal=Journal of Zoology| date=20 August 2009| volume=207| issue=3| pages=371–80| doi=10.1111/j.1469-7998.1985.tb04938.x}}</ref> During an attempt of blood sampling in the nyala, it was found that [[Vitamin E]] levels varied during stress.<ref>{{cite journal| last=Grandin| first=T.| author2=Rooney, M. B.| author3=Phillips, M.| author4=Cambre, R. C.| author5=Irlbeck, N. A.| author6=Graffam, W.| title=Conditioning of nyala (''Tragelaphus angasi'') to blood sampling in a crate with positive reinforcement| journal=Zoo Biology| date=1 January 1995| volume=14| issue=3| pages=261–73| doi=10.1002/zoo.1430140307| hdl=10217/4410| url=https://dspace.library.colostate.edu/bitstream/10217/4410/1/E108.pdf| hdl-access=free}}{{Dead link|date=August 2024 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

==Parasites==
A study of the [[helminth]]s from 77 nyalas from four game reserves in [[Natal Province|Natal]] revealed the presence of ten [[nematode]] species and four nematode genera, a [[trematoda|trematode]] species and paramphistomes (members of superfamily ''[[Paramphistomoidea]]''), and two [[cestode]] genera. The research discovered new parasites that the nyala was host of - namely a ''[[Cooperia rotundispiculum]]'' race, ''[[Gaigeria pachyscelis]]'', a ''[[Gongylonema]]'' species, ''[[Haemonchus vegliai]]'', ''[[Impalaia tuberculata]]'', an ''[[Oesophagostomum]]'' species, a ''[[Setaria]]'' species, ''[[Trichostrongylus deflexus]]'', ''[[Trichostrongylus falculatus]]'', the larval stage of a ''[[Taenia (flatworm)|Taenia]]'' species, a ''[[Thysaniezia]]'' species and ''[[Schistosoma mattheei]]''. ''[[Ostertagia harrisi]]'' and ''C.&nbsp;rotundispiculum'' were the most dominant nematodes in the antelope.<ref>{{cite journal| last=Boomker| first=J.|author2=Horak, I.G. |author3=Flamand, J.R. | title=Parasites of South African wildlife. XII. Helminths of Nyala, ''Tragelaphus angasii'', in Natal| journal=The Onderstepoort Journal of Veterinary Research| year=1991| volume=58| issue=4| pages=275–80| pmid=1780128}}</ref>

Another study of 97 blood samples of South African nyalas revealed the presence of [[tick]]-borne hemoparasites (blood parasites). The methods used were [[polymerase chain reaction]] (PCR) and reverse line blot (RLB) hybridization. The dominant parasites were ''[[Theileria]]'' species, ''[[Theileria buffeli|T.&nbsp;buffeli]]'', ''[[Theileria bicornis|T.&nbsp;bicornis]]'', ''[[Ehrlichia]]'' species, ''[[Anaplasma marginale]]'' and ''[[Anaplasma bovis|A.&nbsp;bovis]]''.<ref>{{cite journal| last=Pfitzer| first=S.|author2=Oosthuizen, M.C. |author3=Bosman, A.M. |author4=Vorster, I. |author5= Penzhorn, B.L. | title=Tick-borne blood parasites in nyala (''Tragelaphus angasii'', Gray 1849) from KwaZulu-Natal, South Africa| journal=Veterinary Parasitology| year=2011| volume=176| issue=2–3| pages=126–31| pmid=21145660| doi=10.1016/j.vetpar.2010.11.006| url=https://repository.up.ac.za/bitstream/2263/17458/1/Pfitzer_Tick%282011%29.pdf| hdl=2263/17458}}</ref> Ten tick species, two [[louse]] species and a louse fly species were recovered in a study of 73 nyalas at Umfolozi, Mkuzi and Ndumu Game Reserves in northeastern KwaZulu-Natal in 1983 and 1984 and an additional six individuals in 1994. It was found that nyalas were hosts to all stages of development in ''[[Boophilus decoloratus]]'', ''[[Rhipicephalus appendiculatus]]'' and ''[[Rhipicephalus muehlensi|R.&nbsp;muehlensi]]'' and the immature stages of ''[[Amblyomma hebraeum]]'' and ''[[Rhipicephalus maculatus]]''. Adult males served hosts to more ticks and lice than adult females did.<ref>{{cite journal| last=Horak| first=I.G.|author2=Boomker, J. |author3=Flamand, J.R. | title=Parasites of domestic and wild animals in South Africa. XXXIV. Arthropod parasites of nyalas in north-eastern KwaZulu-Natal| journal=The Onderstepoort Journal of Veterinary Research|date=September 1995| volume=62| issue=3| pages=171–9| pmid=8628570}}</ref> Also, a [[Trypanosoma|trypanosome]] was isolated from a nyala, wild-caught in Mozambique, which was diagnosed and found as akin to ''[[Trypanosoma vivax]]'', based on biological, morphological and molecular data.<ref name=rodrigues>{{cite journal|last1=Rodrigues|first1=A. C.|last2=Neves|first2=L.|last3=Garcia|first3=H. A.|last4=Viola|first4=L. B.|last5=Marcili|first5=A.|last6=Da Silva|first6=F. M.|last7=Sigauque|first7=I.|last8=Batista|first8=J. S.|last9=Paiva|first9=F.|last10=Teixeira|first10=M. M. G.|title=Phylogenetic analysis of ''Trypanosoma vivax'' supports the separation of South American/West African from East African isolates and a new ''T. vivax''-like genotype infecting a nyala antelope from Mozambique|journal=Parasitology|date=28 August 2008|volume=135|issue=11|pages=1317–28|doi=10.1017/S0031182008004848|pmid=18752705|s2cid=20442593 }}</ref>

==Diseases==
[[File:Nyala heart (Tragelaphus angasii).jpg|thumb|200px|Nyala heart]]
The nyala can also suffer from [[myopathy]]. In between January 1973 and June 1981, 21 nyalas succumbed to the disease. The main symptoms were stiffness, inability to rise, and failure to suckle in newborns. [[Necrosis]] (that is, the premature death of cells in a living tissue) and [[ossification|mineralization]] were found in the skeletal muscle after a histological analysis. In the juveniles there was acute necrosis of the [[cardiac muscle]]. In adults, there was interstitial [[fibrosis]] of the cardiac muscle, along with [[arteriosclerosis]].<ref>{{cite journal| last=Liu| first=S.|author2=Dolensek, E.P. |author3=Herron, A.J. |author4=Stover, J. |author5= Doherty, J.G. | title=Myopathy in the nyala| journal=Journal of the American Veterinary Medical Association| year=1982| volume=181| issue=11| pages=1232–6| doi=10.2460/javma.1982.181.11.1232| pmid=7174434}}</ref>

In a report published in 1994 entitled "Epidemiological observations on spongiform encephalopathies in captive wild animals in the British Isles", it was noted that [[spongiform encephalopathy]] had been diagnosed in one nyala captive in a zoo.<ref name=bse>{{cite journal| last=Kirkwood| first=J.|author2=Cunningham, A. | title=Epidemiological observations on spongiform encephalopathies in captive wild animals in the British Isles| journal=Veterinary Record| date=24 September 1994| volume=135| issue=13| pages=296–303| doi=10.1136/vr.135.13.296| doi-broken-date=27 May 2025| pmid=7817514| s2cid=21133285}}</ref> The nyala was formerly affected by the disease [[rinderpest]], although the viral disease is considered eradicated now.<ref name=iucn/>

==Ecology and behavior==
[[File:Nursing nyala.jpg|thumb|left|Nursing juvenile]]
The nyala is active mainly in the early morning and late afternoon. It browses during the day if temperatures are {{convert|20|-|30|C|F}} and during the night in rainy season.<ref name=tello/> These antelopes rest in thick bushes during the hot hours of the day.<ref name=huffman/> The nyala is very shy and cautious in nature, and often remains hidden rather than coming out in the open. Most sightings of the nyala in the wild are at [[Depression (geology)|water holes]].<ref name=huffman/> But in protected areas they become less shy and often come out in view of tourists.<ref name=burton/>

Nyala groups are according to sex or mixed. Herds usually browse and drink water together.<ref name=unwin/> Each group consists of two to ten individuals. A study in [[Zinave National Park]] at Mozambique showed that 67% of the observations were of groups of one to three nyalas, and the rest of the herds consisted of up to 30 nyalas. Herds often broke up and re-formed.<ref name=tello/> Generally adult males remain alone. Females often remain near their mothers when they have their offspring, so the relationships in female herds may be closer than those of males.<ref name=adw/><ref>{{cite book|author=Alden, P. C.|author2= Estes, R. D.|author3= Schlitter, D.|author4= McBride, B. |year=1995|title=National Audubon Society Field Guide to African Wildlife |publisher=Chanticleer Press}}</ref>

Alert and wary in nature, the nyala use a sharp, high, dog-like bark to warn others in a group of danger. This feature is mainly used by females.<ref name=adw/> They also react to the alarm calls of [[impala]], [[baboon]] and kudu. The impala has been found to react to the calls of the nyala as well.<ref name=adw/> The main predators of nyala are [[lion]], [[leopard]], [[cheetah]], [[spotted hyena]], [[African wild dog]] and [[nile crocodile]] while baboons and [[Bird of prey|raptorial birds]] are predators of juveniles.<ref name=tello/><ref name=planet>{{cite book|last=Fitzpatrick |first=M.|title=South Africa, Lesotho & Swaziland|publisher=Lonely Planet|page=78|year=2006|author2=Armstrong, K. }}</ref>

===Diet===

As a [[herbivore]], the nyala's diet consists of foliage, fruits, flowers and twigs. During the rainy season they feed upon the fresh grass. They need a regular intake of water, and thus choose places with a water source nearby. However, they are adapted to live in areas with only a seasonal availability of water.<ref name=adw/> A study in [[Zululand District Municipality|Zululand]] showed that the nyala fed mainly in the early morning and the late afternoon.<ref name=nowak>{{cite book| last=Nowak| first=R. M.| title=Walker's Mammals of the World| year=1999| publisher=Johns Hopkins University Press| location=Baltimore, Md.| isbn=978-0-8018-5789-8| edition=6th | page=1137}}</ref> They feed at night during the rainy season.<ref name=planet/>

A study in [[Mkhuze Game Reserve]] and [[Ndumu Game Reserve]] in Natal focused on the dietary habits of the impala and the nyala showed that the amount of [[dicotyledon]]s in their diets varied seasonally. In the dry season, the nyala's dicotyledon diet content was 83.2% and the impala's 52%. In this season, the diet grew richer in fiber and dietary proteins were less. The reverse occurred in the rainy season. As the rainy season arrived, both species took to a diet of mainly [[monocotyledon]]s, and the impala consumed more of them. The diet contained more proteins than fiber.<ref name=rooyen>{{cite journal| author=A. F. V. Rooyen| title=Diets of impala and nyala in two game reserves in Natal, South Africa| journal=South African Journal of Wildlife Research| year=1992| volume=22| issue=4| pages=98–101| issn=0379-4369}}</ref>

Another study was done to find whether the sexual dimorphism in the nyala influenced its foraging habits. Vegetation surveys were conducted with the end of each feeding bout. It was found that females spent equal periods of time foraging in all the three habitats, but males preferred sand forest more. More differences were noted, as males ate woody species at a greater average height whereas females fed from the low [[herbaceous layer]]. It was concluded that the differences resulted from varying nutritional and energetic demands according to their diverse body sizes and differing reproductive strategies.<ref name=kirby>{{cite journal| last=Kirby|first=T. |author2=Shannon, G. |author3=Page, B. |author4=Slotow, R.| title=The influence of sexual dimorphism on the foraging behaviour of the nyala (''Tragelaphus angasii'')| journal=Current Zoology  |date=August 2008| volume=54| issue=4| pages=561–8| url=http://www.actazool.org/paperdetail.asp?id=10863&volume=54&number=4&bgpage=561&endpage=568&year=2008&month=8}}</ref>

===Reproduction===
[[File:Fighting Nyalas.JPG|thumb|left|Males fighting over dominance]]
[[File:Nyala (Tragelaphus angasii) young male 2w.jpg|thumb|Male, two weeks old<br/>[[Tswalu Kalahari Reserve]], [[South Africa]]]]
[[File:Nyala (Tragelaphus angasii young male 2w head 2.jpg|thumb|Male, two months old<br/>feeding]]
The nyala breeds throughout the year, but [[mating]] peaks in spring and autumn. The reason for this is still unknown, but attributed to the [[photoperiodism|photoperiod]] and the feeding habits of the animal.<ref name=anderson2>{{cite journal| last=Anderson| first=J. L.| title=Reproductive seasonality of the nyala ''Tragelaphus angasi''; The interaction of light, vegetation phenology, feeding style and reproductive physiology| journal=Mammal Review| year=1979| volume=9| issue=1| pages=33–46| doi=10.1111/j.1365-2907.1979.tb00230.x}}</ref> Females reach [[sexual maturity]] at 11 to 12 months of age and males at 18 months (though they are socially immature until five years old),<ref name=huffman/> though they begin to show active [[spermatogenesis]] at 14 months.<ref name=anderson>{{cite journal| last=Anderson| first=J. L.| title=Reproduction in the Nyala (''Tragelaphus angasi'') (Mammalia: Ungulata)| journal=Journal of Zoology| date=20 August 2009| volume=204| issue=1| pages=129–42| doi=10.1111/j.1469-7998.1984.tb02366.x}}</ref>

Before ovulation, the [[Graafian follicles]] reach a length of at least {{convert|6.7|cm|in|abbr=on}}.<ref name=anderson/> A female's estrous cycle is about 19 days long. Males will attempt to mate with the female for two days of the cycle, but she allows it for only six hours per cycle. When the male enters a females' herd during mating, he makes a display by raising his white dorsal crest, lowering his horns and moving stiffly. As in many other animals, the males fight over [[Dominance (ethology)|dominance]] during mating.<ref name=adw/>

The kidney fat indices (KFIs) of impalas and nyalas have been studied to understand the influence of social class and reproduction on them. To determine the KFI, the kidney is removed and weighed with the fat and once again excluding the fat. The resultant difference is the amount of fat on the kidney. The more the fat, the healthier the animal.<ref name=kfi>{{cite web| last=Karns| first=G.| title=Kidney fat index| url=http://www.skinnymoose.com/outdoorsmorgasbord/2008/07/25/kidney-fat-index/| publisher=The Outdoor Smorgasbord| access-date=1 August 2012| date=July 25, 2008}}</ref> In [[rut (mammalian reproduction)|rut]], male nyalas had lower KFIs, which did not vary much with the season. Pregnant females of both nyala and impala had higher KFIs than non-pregnant ones.<ref name=kfi2>{{cite journal| author=A.F. V. Rooyen| title=Variation in body condition of impala and nyala in relation to social status and reproduction| journal=South African Journal of Wildlife Research| year=1993| volume=23| issue=2| pages=36–8| issn=0379-4369}}</ref>

There is a significant increase in [[corpus luteum]] in the last third of gestation.<ref name=anderson/> Gestation is of seven months. A single calf is born, weighing {{convert|5|kg|lb|abbr=on}}. Birth takes place generally away from the sight of predators, in places such as a thicket. The calf remains hidden for up to 18 days, and the mother nurses it at regular intervals. The calf remains with its mother until the birth of the next calf, during which males in rut drive it away from the mother.<ref name=adw/>

==Habitat and distribution==
[[File:Nyalas.jpg|thumb|right|Nyalas choose habitat with fresh water sources nearby.]]
The nyala inhabits dense lowland woodlands and thickets, mainly in southern Malawi, Mozambique, Zimbabwe, and eastern South Africa. It chooses places with good quality grasslands as well as provision of fresh water.<ref name=adw/> It also inhabits lush green river country.<ref name=burton/> The nyala's natural range stretches across southeast Africa from the Lower Shire Valley in Malawi through Mozambique and Zimbabwe to eastern South Africa and Eswatini.<ref name=iucn/>

The geographic distribution of the nyala may be based on the genetic variation. According to a study of nyala in South Africa, Mozambique, Malawi and Zimbabwe, there was a marked difference in the [[gene frequencies]] at three [[microsatellite]] [[locus (genetics)|loci]]. Mitochondrial DNA analysis revealed the presence of a unique [[haplotype]] in individuals from each location. Thus, the geographic variation in the nyala may be due to a distribution pattern based on habitat specificity.<ref name=grobler>{{cite journal| last=Grobler| first=J.P.|author2=Pretorius, D.M. |author3=Botha, K. |author4=Kotze, A. |author5=Hallerman, E.M. |author6= Jansen Van Vuuren, B. | title=An exploratory analysis of geographic genetic variation in southern African nyala (''Tragelaphus angasii'')| journal=Mammalian Biology - Zeitschrift für Säugetierkunde| date=1 September 2005| volume=70| issue=5| pages=291–9| doi=10.1016/j.mambio.2005.01.001| bibcode=2005MamBi..70..291G| language=en, de| hdl=10019.1/117692| hdl-access=free}}</ref>

Today nyala are found in South African protected areas in the [[Ndumo Game Reserve]], uMkuze Game Reserve and [[Hluhluwe-Umfolozi Game Reserve]], all in [[KwaZulu-Natal]], as well as in [[Kruger National Park]]. As of 1999, 10–15% of nyala occurred on private land. Efforts are being made to retain the populations of nyala in [[Gorongosa National Park]] and [[Banhine National Park]] in Mozambique.<ref name=iucn/> Nyala also thrive in [[Lengwe National Park]] in Malawi.

Nyala have never been observed showing [[territory (animal)|territoriality]]. Territories of either sex overlap extensively.<ref name=tello>{{cite journal| author=Tello, Jose L.P.L.|author2=Van Gelder, Richard G. | title=The natural history of nyala, ''Tragelaphus angasi ''(Mammalia, Bovidae) in Mozambique| journal=Bulletin of the American Museum of Natural History| volume=155| page=323| publisher=American Museum of Natural History| location=New York|year=1975 |hdl=2246/613 }}</ref> The home ranges of males are approximately equal to that of females, about {{convert|10|km2}} in area.<ref name=tello/>

[[File:South African Safari Wildlife1.jpg|thumb|right|Young nyala bull in the Kruger National Park]]

==Threats and conservation==
The major threats to the population of the nyala are poaching, habitat loss, agriculture and cattle grazing.<ref name=iucn/> Rinderpest outbreaks have also contributed in population loss.<ref name=iucn/> This species is currently of [[Least Concern]], and the population is considered stable by both the IUCN and [[CITES]].<ref name=antelope>{{cite web| last=Richards| first=M.| title=Nyala antelope (''Tragelaphus angasi'')| url=http://www.antelopetag.com/assets/docs/Antelope/Lowland_Nyala.pdf| access-date=1 August 2012| author2=Shurter, S.| archive-url=https://web.archive.org/web/20130619044937/http://www.antelopetag.com/assets/docs/Antelope/Lowland_Nyala.pdf| archive-date=19 June 2013| url-status=dead}}</ref> As of 1999, the total population of the nyala was around 32,000 individuals. More recent estimates show that South Africa has at least 30,000 nyalas, with 25,000 in KwaZulu-Natal. There are now more than 1,000 on protected areas and ranches in Eswatini. In Mozambique there are not more than 3,000, in Zimbabwe over 1,000, and numbers in Malawi have fallen from 3,000 to about 1,500. Namibia has the smallest population, at about 250.<ref name=iucn/>

Today over 80% of the total population is protected in national parks and sanctuaries, mostly in South African protected areas. In South Africa there is a high demand for adult males as game trophies.<ref name=iucn/>

==References==
{{Reflist|2}}

==External links==
{{Portal|Mammals}}
* [https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=625128 Information at ITIS]
* {{Commons category-inline|Tragelaphus angasii}}
* {{Wikispecies-inline|''Tragelaphus angasii''}}

{{Artiodactyla|R.4}}
{{Taxonbar|from=Q239032}}
{{Authority control}}

[[Category:Tragelaphus]]
[[Category:Mammals of South Africa]]
[[Category:Mammals of Eswatini]]
[[Category:Mammals of Malawi]]
[[Category:Mammals of Mozambique]]
[[Category:Mammals of Zimbabwe]]
[[Category:Fauna of East Africa]]
[[Category:Mammals described in 1849]]
[[Category:Taxa named by George French Angas]]