Mountain zebra
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Mountain zebra ( Equus zebra ) |
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| Linnaeus , 1758 |
The mountain zebra ( Equus zebra ) is a zebra from the horse family ( Equidae ) and belongs to the order of the odd ungulate (Perissodactyla). There are two subspecies, the Hartmann mountain zebra ( Equus zebra hartmannae ) and the Cape mountain zebra ( Equus zebra zebra ). The mountain zebra occurs in south-western Africa and lives mainly in semi-desert mountains and highlands. It lives in small herds, consisting of a male animal, one to several female animals and the young animals. The main food of the mountain zebra is various grasses. Both subspecies are endangered in their existence.
features
Habitus
The mountain zebra is a medium-sized horse and reaches a head-trunk length of 220 cm with a shoulder height of 116 to 144 cm. Mares weigh between 234 and 256 kg, stallions are slightly larger and reach a body weight of 250 to 343 kg. The body and limbs are strong, on the front legs there are large callus-like elevations up to 7.6 cm in diameter ( chestnuts ). All limbs each end in a toe with a very compact hoof. The head is large and equipped with ears up to 23 cm long, which have rounded ends, the upper edges are often colored white. The mouth is colored black. The overall coat consists of very short hairs that are only 1 cm long on average. The longest hair is on the short standing mane and on the tail tassel.
As with all zebras , the stripe pattern is very typical of the species and also has an individual design for each animal. From the Plains Zebra ( Equus quagga ), the mountain zebra is distinguished by wider, black and chocolate brown stripes and narrower white gaps, so that the whole animal dark overall effect that color is white but still. The "shadow stripes" of the plains zebra are missing. The stripes are narrowest on the head and widest on the buttocks, where the white spaces are also very wide. On the legs, the stripes continue to the hooves, with the front legs having thinner stripes than the hind legs, while the typical black horizontal stripes are limited to the croup and the base of the tail. A dark vertical stripe runs across the back and stomach; With the exception of the longitudinal stripe, the belly is otherwise white. The stripe pattern already forms in the embryonic age and is detectable from the fourth week.
Skull and dentition features
The skull is long and narrow and has an almost straight forehead line. The length is on average greater than that of plains zebras and is in their upper variation width with an average of 47 cm. As with Grevy's zebra ( Equus grevyi ), the occiput extends far beyond the attachment surfaces of the cervical vertebrae. The nasal bone is short and the inside of the nose is very large. The eye socket is behind the last molar. It is large and much more rounded than the plains zebra.
The lower jaw of the mountain zebra is very strong with a high jawbone and elongated joint ends. It reaches 41 cm in length. The dental formula of a full-grown animal is: The first premolar is still formed in the deciduous dentition . The canine is not always present, it is often absent in mares. If it occurs in females, however, it is much smaller than in males. There is a large diastema between the anterior and posterior teeth . The premolars and molars are typically very high crowned ( hypsodontal ) for all horses , the chewing surfaces have a complex pattern of folds in the tooth enamel . A typical feature of the rear molars of the lower jaw is a V-shaped incision between two projections of the tooth enamel ( metaconid and metastylid ), which places the mountain zebra in relation to the more original, so-called stenonine or non-caballine horses.
Sensory performances and vocalizations
At least four sounds are known in the mountain zebra. When in danger, stallions utter a high-pitched whistle to warn the herd. Young animals squeal when confronted with a stallion. Male animals also let out a snort, during which air was audibly sucked in beforehand. This also serves as an alarm call. Stallions emit a hiss that can only be heard over a short distance and is ejected between pressed lips when eating when a herd member comes too close.
distribution
The mountain zebra has a smaller range than the plains zebra. It lives exclusively in south-western Africa , where it inhabits mountainous plateaus at heights of up to 2000 m. Originally the distribution area reached from the southernmost part of South Africa via Namibia to the southwestern part of Angola . The Cape Mountain Zebra inhabited the plateaus of the Western Cape , Eastern Cape and North Cape . Today, natural populations occur only in the Mountain Zebra National Park near Port Elizabeth in the Eastern Cape, in the Gamkaberg Nature Reserve in the Western Cape and in the Kamanassie Mountains, also in the Western Cape. Mainly from stocks from the Mountain Zebra National Park, animals were resettled in the further original range. The Hartmann mountain zebra, named after Anna Hartmann, the wife of the discoverer of this subspecies Georg Hartmann (1865–1946), was found from the transition zones of the Namib desert to the inner highlands of Namibia. Today the animals live in rather inhospitable areas at water points. Four populations are known in Namibia, these colonize the Kunene region south to the Ugab River and east to Outjo , the Erongo Mountains , the area from the Swakop River south to the Naukluft Mountains and east to the Khomashochland and the area between the Fish River Canyon and the orange . In South Africa there are stocks in three nature reserves in the North Cape and some introduced groups in the Western and Eastern Cape, which, however, lie outside the natural range. No information is available about the population from the Iona National Park in Angola, which existed in the early 1970s.
The habitat of the mountain zebra includes semi-desert, rugged and often rocky regions of the mountains and highlands, which are characterized by steep slopes. Despite the sometimes inhospitable conditions, these landscape areas have diverse vegetation communities. However, the prerequisite for the presence of the mountain zebra is that water is available all year round. The mountain zebra rarely appears sympatric to the plains zebra, as its harder and faster-growing hooves do not wear out enough in flat savannah areas with softer ground and therefore do not allow the animals to stay longer there.
Way of life
Territorial behavior
Mountain zebras live in small groups that do not maintain their own districts, but instead inhabit home ranges during the rearing of young animals , which can greatly overlap with the areas of other small mountain zebra groups. The size of these areas ranges from 3 to 16, sometimes up to 20 km². The individual associations consist of an older stallion and up to five mares with their foals. The largest observed association comprised 13 animals (stallion, five mares, seven foals). There is a hierarchy within the herds , but in certain situations the leadership may alternate. In general, stallions lead herds to water and food sources, when they leave them or when danger looms, the highest-ranking mare leads, usually the one with the youngest foal, and the stallion runs behind as the rearguard. Within the group there are running, fighting and greeting games for both foals and adult animals, as well as mutual grooming. The dominant stallion covers the urine and faeces of the mares and young stallions with his feces .
The herds are relatively stable, a stallion can lead an association for up to ten years before being driven out of his position by a younger competitor. The mares can stay in their association for a lifetime, but when the herds get too big they sometimes split up. A growing stallion then takes over the leadership of the split off association. In addition to these family associations, growing stallions get together in "bachelor groups" that have not yet founded their own group. Even old stallions that have been driven away by young competitors sometimes form small groups.
When two herds meet, the dominant stallions engage in a ritualized fight, which usually consists of nose contact, smelling the genitals and rubbing the body against each other. Usually the groups then separate again. Aggressive stallions lower their heads, straighten their necks, and bare their teeth. Animals that are not dominant show a gesture of submission, resembling the face of a brute face , with their heads raised and upper lip extended. Fighting has rarely been observed, but takes place when a new stallion tries to take over the herd and occurs with kicks of both the front and rear legs against the head and torso and with bites.
nutrition
The mountain zebra is largely specialized in hard, silicic acid-containing grass food ( grazing ) and adapted to it with high-crowned molars and a high proportion of dental cement . Long-leaved and juicy plants are preferred. The most common food plants include various sweet grasses such as Themeda , Aristida , Heteropogon , Enneapogon and Merxmuellera , but also bristle and fingergrass . Furthermore, citric , Hundszahn- and eragrostis consumed. There is a clear selection of food plants, since only around 26% of all available plants in a pasture are actually eaten. The plants are bitten off 4 to 8 cm above the ground. Occasionally, seeds are also ingested, and in some regions woody plants such as wolfberry and acacia .
A seasonal selection of vegetation communities in the mountain zebra can be seen. In the cool winters, rockier areas are often sought out, where caves and rock shelters serve as protection. The areas are also dependent on water supplies and salt and mineral leaks. Furthermore, suhl spots are important, which often contain moist sand, but can also represent simple dust spots.
Reproduction
A male zebra is sexually mature at three and a half years, but the first mating takes place much later, as it is only fully grown at the age of seven and strong enough to take over a herd at the earliest five years. A female mountain zebra is sexually mature at around two years of age, the youngest known pregnant animal was 26 months old. As a rule, however, the mother animal is around five years old when the first foal is born. The birth intervals are on average a little more than two years. Mating takes place exclusively in the herd and is the prerogative of the dominant stallion. The mountain zebra is ready to mate all year round, but there is an accumulation in summer.
The gestation period lasts almost a year (an average of 364 days), after which a single foal is usually born. The foal is about 120 cm long at birth and weighs 25 kg. It usually stays very close to the mother in the first few weeks. This actively protects the young animal from contact with other herd members and drives them away if they come too close. After a few days the foal starts to eat grass, but at first it also sucks milk every hour, which takes about two minutes and takes place during the day. After three months the frequency of daily suckling decreases significantly, after ten months a young animal only needs milk three times a day. Weaning ends at around 20 months. Both male and female young animals are not chased away after sexual maturity, but voluntarily leave the herd, which takes place from around 22 months and which the lead stallion tries to prevent in part. This also happens regardless of whether the dam gives birth to a new foal. However, some young animals stay in the herd for up to three years. Young stallions often form in bachelor groups, young mares are taken in by other herds. However, the animals also return to their original herds at irregular intervals.
Interactions with other animal species
The predators of the mountain zebra are lions , leopards , cheetahs and spotted hyenas , and wild dogs occasionally attack . However, the mountain zebra is good at defending itself with kicks and sometimes kills the attacker. The zebra shape reacts to alarm signals from the wildebeest , but rarely to those of smaller species such as the springbok or the buntbock . Group formations with antelopes like the plains zebra are not known. Pale- winged starlings , red-winged starlings and mourning drongos can often be found near groups of zebra pecking for parasites on the animals' backs.
Parasites
External parasites of the mountain zebra are predominantly ticks , especially of the genera Amblyomma , Margaropus and Hylalomma . Endoparasites are very common. These include gastric dasseln and roundworms , around two dozen genera of which have been found in the mountain zebra. Tapeworms and Babesia are also known. The mountain zebra acts as an intermediate host for the Apicomplexa of the genus Sarcocystis , whose ultimate host is, among other things, the domestic dog . The infestation of internal parasites often occurs during the cool season, the mountain zebra becomes infected with part of the parasites through water intake.
Systematics
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Internal systematics of the genus Equus according to Jónsson et al. 2014
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The mountain zebra belongs to the genus Equus and is therefore a representative of today's modern horses. Within this genus, the zebra form belongs to the group of stenonine or non-caballine horses, as the characteristic shape of the lower molars shows. Furthermore, the mountain zebra is assigned to its own subgenus, Hippotigris , into which the plains zebra is also integrated. However, some DNA analyzes do not show a very close relationship to the plains zebra, but a closer connection to the Asian donkey ( Equus hemionus ), more precisely to the onager, or to the African donkey ( Equus asinus ). In these cases the subgenus Hippotigris would not be monophyletic . According to other DNA studies, the zebras form a closer family group. In all studies the wild horse ( Equus ferus ) forms the outer group.
Two subspecies are distinguished within the mountain zebra:
- Hartmann's mountain zebra ( E. z. Hartmannae Matschie , 1898); more northern and larger subspecies with somewhat narrower black stripes
- Cape mountain zebra ( E. z. Zebra Linnaeus , 1758); more southern and smaller subspecies with wider black stripes
In a revision of the odd ungulate from 2011 by Colin Peter Groves and Peter Grubb , both subspecies are regarded as separate species.
Molecular genetic studies in the Cape Mountain Zebra showed that there are very slight genetic differences within the individual populations, which is typical of the fragmented and fragmented occurrence. Taken together, all populations of the Cape Mountain Zebra show a moderate variability and imply a higher diversity of the subspecies that still exists, which could be increased by relocating individual groups. The Hartmann mountain zebra, on the other hand, shows a very high degree of variability overall and roughly achieves the same intraspecific diversity as the plains zebra. Interestingly, these analyzes do not yet support the monophyletic origin of the two subspecies of the mountain zebra.
Africa was first entered in the Pliocene by stenonine horses, which also form the tribe of the zebras and the African donkey. The mountain zebra itself has only rarely been passed down in fossil form. One skull comes from the Upper Orange River in South Africa and was assigned to the fossil subspecies E. z. assigned to greatheadi . In the late Pistocene it occurs in South Africa together with the large species Equus capensis , the Cape zebra, which is less specialized in grass forage. According to anatomical studies, this species is more closely related to the Grevy's zebra ( Equus grevyi ); molecular genetic studies also show a closer relationship to the plains zebra. Both species were found together in the Bloomplaas Cave on the southern edges of the Swartberg Mountains , known for its extensive fossils dating from 18,000 years ago to modern times. Studies have shown that grass-eating mammals benefited from the expansion of grasslands in the late last glacial period, so that the mountain zebra was also much more common. At the end of the Pleistocene , however, the populations collapsed, which was the result of the climate changes at that time and the associated increased expansion of bush and woodland.
Threat and protection
The habitat of the mountain zebra is today very fragmented, but it is assumed that the total number of animals was never particularly high even in historical times. The first protective measures for the Cape Mountain Zebra took place as early as 1742, when hunting the animals was banned. Nevertheless, they continued to be hunted excessively, mainly because of the fur, but also as food competitors for domesticated and agricultural large animals and because they often destroyed fences on the way to water sources. In the 1930s, the Cape mountain zebra was on the verge of extinction when only 45 living mountain zebras were found in South Africa in one count. To save the subspecies, the Mountain Zebra National Park was created in 1937 with a founding population of five stallions and one mare. In 1950 only two stallions were still alive, so that a neighboring farmer offered five more stallions and six mares. When the park was enlarged to 65.4 km² in 1964, 55 mountain zebras lived there; today the population in the national park again comprises around 350 animals. Various groups from the Mountain Zebra National Park were resettled in other protected areas, for example in the Bontebok and Karaoo National Parks and in the Kammanassie Nature Reserve . Around 50 animals live in the latter. The IUCN specifies the number of Cape Mountain Zebras as 1,500, which live in around 30 public and private protected areas and lists the subspecies as vulnerable ("threatened"), it is no longer directly threatened with extinction. The greatest threat to the Cape Mountain Zebra is a hybridization with the northern subspecies, the Hartmann Mountain Zebra, which was introduced in the South African provinces of the Eastern and Western Cape.
The main reason for the endangerment of the Hartmann mountain zebra is the competition of the cattle farmers who shoot mountain zebras legally or illegally in order to secure grazing grounds for their large animals. There is also a legal trade in zebra skin in Namibia. There are now about 72,000 Hartmann's mountain zebras in Namibia (2004; wildlife population in Namibia ). Many of the animals live in the state and private protected areas near the Namib as well as on private farmland. The IUCN has now also classified the Hartmann mountain zebra as vulnerable .
Conservation efforts coordinated by the Equid Specialist Group of the IUCN include observations and censuses of animals in the protected areas, among other things, local regulation of bush fires, which are necessary for fresh, regrowing grass and the relocation of populations. This also includes those of the Hartmann mountain zebra in the Goegap nature reserve in the South African province of North Cape, the number of which makes up a third of the individuals of the Cape mountain zebra there. These are to be replaced by animals of the southern subspecies in order to separate the two subspecies from each other again in their distribution areas in order to prevent hybridization.
literature
- LB Penzhorn: Equus zebra. Mammalian Species 314, 1988, pp. 1-7
- Banie Penzhorn: Equus zebra Mountain Zebra. In: Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume V. Carnivores, Pangolins, Equids and Rhinoceroses. Bloomsbury, London, 2013, pp. 438-443
- DI Rubenstein: Equidae. In: Don E. Wilson and Russell A. Mittermeier (eds.): Handbook of the Mammals of the World. Volume 2: Hooved Mammals. Lynx Edicions, Barcelona 2011, pp. 142-143 ISBN 978-84-96553-77-4
Individual evidence
- ↑ a b c d e f g h i j k l m n o p q r L. B. Penzhorn: Equus zebra. Mammalian Species 314, 1988, pp. 1-7
- ^ Peter Grubb: Equus burchelli. Mammalian Species 157, 1981, pp. 1-9
- ^ A b Véra Eisenmann and C. de Giuli: Caractères distinctifs entre vrais Zèbres (Equus zebra) et Zèbres de Chapman (Equus burchelli antiquorum) d'après l'étude de 6O têtes osseuses. Mammalia 38, 1974, pp. 509-543
- ↑ a b Ann Forstén: Mitochondrial DNA time-table and the evolution of Equus: comparison of molecular and paleontological evidence. Annales Zoologici Fennici 28, 1992, pp. 301-309
- ↑ Bo Beolens, Michael Watkins, Michael Grayson: The Eponym Dictionary of Mammals. JHU Press, 2009, ISBN 9780801893049 , p. 179.
- ^ Banie Penzhorn: Equus zebra Mountain Zebra. In: Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume V. Carnivores, Pangolins, Equids and Rhinoceroses. Bloomsbury, London, 2013, pp. 438-443
- ↑ a b c d e P. Novellie: Equus zebra. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.1. , 2011, last accessed on August 12, 2012 ( [1] )
- ↑ a b Yoshan Moodley and Eric H. Harley: population structuring in mountain zebras (Equus zebra): The molecular Consequences of divergent demographic histories. Conservation Genetics 6, 2005, pp. 953-968
- ^ A b c d e f Hans Klingel: Social organization and behavior of Hartmann and mountain zebras (Equus zebra hartmannae and E. z. Zebra). Journal of Mammalian Psychology 25 (1), pp. 76-88
- ↑ a b Laurence H. Watson, Helena E. Odendaal, Tom J. Barry and Jacques Pietersen: Population viability of Cape mountain zebra in Gamka Mountain Nature Reserve, South Africa: the influence of habitat and fire. Biological Conservation 122, 2005, pp. 173-180
- ↑ Ronald Fayer: Cryptosporidium: a water-borne zoonotic parasite. Veterinary Parasitology 126, 2004, pp. 37-56
- ↑ a b Hákon Jónsson, Mikkel Schubert, Andaine Seguin-Orlando, Aurélien Ginolhac, Lillian Petersen, Matteo Fumagallic, Anders Albrechtsen, Bent Petersen, Thorfinn S. Korneliussen, Julia T. Vilstrup, Teri Lear, Jennifer Leigh Myka, Judith Lundquist, Donald C. Miller, Ahmed H. Alfarhan, Saleh A. Alquraishi, Khaled AS Al-Rasheid, Julia Stagegaard, Günter Strauss, Mads Frost Bertelsen, Thomas Sicherheitsitz-Ponten, Douglas F. Antczak, Ernest Bailey, Rasmus Nielsen, Eske Willerslev and Ludovic Orlando: Speciation with gene flow in equids despite extensive chromosomal plasticity. PNAS 111 (52), 2014, pp. 18655-18660
- ↑ a b Samantha A. Price and Olaf RP Bininda-Emonds: A comprehensive phylogeny of extant horses, rhinos and tapirs (Perissodactyla) through data combination. Zoosystematics and Evolution 85 (2), 2009, pp. 277-292
- ↑ Julia T. Vilstrup, Andaine Seguin-Orlando, Mathias Stiller, Aurelien Ginolhac, Maanasa Raghavan, Sandra CA Nielsen, Jacobo Weinstock, Duane Froese, Sergei K. Vasiliev, Nikolai D. Ovodov, Joel Clary, Kristofer M. Helgen, Robert C. Fleischer, Alan Cooper, Beth Shapiro, and Ludovic Orlando: Mitochondrial Phylogenomics of Modern and Ancient Equids. PlosONE 8 (2), 2013, p. E55950.
- ^ A b Ludovic Orlando, Jessica L. Metcalf, Maria T. Alberdi, Miguel Telles-Antunes, Dominique Bonjean, Marcel Otte , Fabiana Martin, Véra Eisenmann, Marjan Mashkour, Flavia Morello, Jose L. Prado, Rodolfo Salas-Gismondi, Bruce J. Shockey, Patrick J. Wrinn, Sergei K. Vasil'ev, Nikolai D. Ovodov, Michael I. Cherry Blair Hopwood, Dean Male, Jeremy J. Austin, Catherine Hänni and Alan Cooper: Revising the recent evolutionary history of equids using ancient DNA. PNAS 106, 2009, pp. 21754-21759
- ↑ Colin P. Groves and Peter Grubb: Ungulate Taxonomy. Johns Hopkins University Press, 2011, pp. 1–317 (p. 16)
- ↑ Eline D. Lorenzen, Peter Arctander and Hans R. Siegismund: High variation and very low differentiation in wide ranging plains zebra (Equus quagga): insights from mtDNA and microsatellites. Molecular Ecology 17, 2008, pp. 2812-2824
- ↑ Thomas M. Kaiser and Tamara A. Franz-Odendaal: A mixed-feeding Equus species from the Middle Pleistocene of South Africa. Quaternary Research 62 (3), 2004, pp. 316-323
- ↑ CS Churcher: Equus grevyi Mammalian Species No. 453, 1993, pp. 1-9
- ↑ J. Tyler Faith: Palaeozoological insights intomanagement options for a threatened mammal: southern Africa's Cape mountain zebra (Equus zebra zebra). Diversity and Distributions 18, 2012, pp. 438-447
- ↑ Laurence H. Watson and Peter Chadwick: Management of Cape mountain zebra in the Kammanassie Nature Reserve, South Africa. South African Journal of Wildlife Research, 37 (1), 2007, pp. 31-39
Web links
- Equus zebra in the endangered Red List species the IUCN 2012. Posted by: Equid Red List Authority, 2008. Accessed February 23, 2013.