Tree hyrax

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Tree hyrax
Steppe forest tree hyrax (Dendrohyrax arboreus)

Steppe forest tree hyrax ( Dendrohyrax arboreus )

Systematics
Subclass : Higher mammals (Eutheria)
Superordinate : Afrotheria
without rank: Paenungulata
Order : Schliefer (Hyracoidea)
Family : Hyrax (Procaviidae)
Genre : Tree hyrax
Scientific name
Dendrohyrax
Gray , 1868

The tree hyrax ( Dendrohyrax ), also called forest hyrax, are a genus of mammals of the hyrax that occurs from western and central to eastern and southern Africa . They are small animals that outwardly resemble a guinea pig . They are generally dark in color, distinctive features are the light back spot that surrounds a gland and the long whisker hairs. The tail is short and remains hidden in the fur. Hands and feet have hoof-like nails with the exception of one toe, on which a claw is formed. The tree hyrax live in various tropical forests in the lowlands and mountains. They live tree-dwelling and are good climbers, for protection they hide in tree hollows. They are also nocturnal and solitary. Noteworthy are the nocturnal vocalizations, which are used for social communication. The diet is based on a soft vegetable diet. Reproduction is mostly all year round, after a long gestation period, one or two young animals are born. The genus was introduced in 1868 and today consists of three species. Two of these are not endangered in their existence.

features

Habitus

Rainforest tree hyrax ( Dendrohyrax dorsalis )

The tree hyrax reach a head-trunk length of 43 to 59 cm and a weight of 1.2 to 4.5 kg. With a length of 1 to 3 cm, the tail is only a short stub and hidden in the fur. In appearance, the animals are reminiscent of guinea pigs , but they are on average larger. The body is compact, the limbs are strong. The fur color of the upper side is mostly dark gray to brown, but there are also lighter variants. Scattered in the fur are longer whisker hairs . A light, often yellowish to cream-colored or white spot marks a gland on the posterior back . The belly appears light brown to whitish. Various lighter drawings appear on the face, the rainforest tree hyrax ( Dendrohyrax dorsalis ) shows a noticeable light spot on the chin. The ears of all tree snappers have a round shape, long vibrissae are formed on the face. In the steppe forest ( Dendrohyrax arboreus ) and in the mountain forest tree hyrax ( Dendrohyrax avalidus ) the fur reaches up to the nose, in the rain forest tree hyrax the nose is bare. The hands have four rays and the feet three rays. They end in hoof-like nails, but the inner toe of the foot is typically equipped with a claw for hyrax. In females there is often only one pair of teats in the chest area, but sometimes only one in the groin area. Under certain circumstances, two pairs of teats can also be formed, which can then be located both in the chest and in the groin area or only in the chest area. The male penis is of simple construction, slightly curved and tapering towards the tip, it has a flattened cross-section. The distance to the anus is 17 to 25 mm, which is only a third of the value in the bush hyrax ( Heterohyrax ).

Skull and dentition features

Skull of a rainforest tree dormouse

The skull length varies from 78 to 112 mm, the skull width from 31 to 39 mm. Overall, the skull is characterized by a large and massive structure. The interparietal bone (a skull bone between the occiput and the parietal bones ) usually grows together with the parietal bone, but not in all cases also with the occiput. The temporal ridges are far apart. The postorbital arch is largely closed, but in some cases it is also open. On the lower jaw, the horizontal bone body is low, but not as clearly pronounced as in the hyrax, the underside of the symphysis is often roughened. The mental foramen is located below the first premolar . The ascending branch is rather narrow. The crown process clearly exceeds the articular process in height. The bit consists of 34 teeth and has the following tooth formula on . The canine-like ( caniniform ) is typical . upper incisor . The lower incisors are wide and show three tips lying next to each other, so that a kind of ridge is formed ( tricuspid or trifid ). The trait occurs in both young and old animals. There is a diastema to the rear row of teeth that is 11 to 21 mm long at the top. The anterior lower premolar is always formed. The upper row of premolars is about the same length as the row of molars or is slightly longer. The entire row of molars measures 30.1 to 43.3 mm in length, the premolars take up 15.5 to 22.5 mm. The crowns of the molars are low ( brachyodont ).

distribution

Distribution areas of the three types of tree hyrax

The tree hyrax are common in western, central, eastern and southern Africa . They live in tropical rainforests , mountain forests , gallery forests , open savannah forests , and moist savannas. Their altitude distribution ranges from sea level to high mountain areas around 4500 m. In extremely high regions they are also found in rocky landscapes. The inhabited habitats should mostly be undisturbed. Since the animals are rarely seen due to their hidden way of life, little information is available on the individual population sizes . In some areas such as on the slopes of the Virunga volcanoes and on Kilimanjaro , however, they can occur in higher population densities of sometimes more than 20 individuals per hectare .

Way of life

Territorial behavior

In the way of life, the tree hyrax differ very strongly from the Klipp- ( Procavia ) and the Bush hyrax ( Heterohyrax ). They are mostly nocturnal and spend most of their life in the branches of the trees. They have a firm grip and can climb well despite the lack of claws. This enables them to turn around the trunk and climb down head first. The animals rarely leave the trees, usually to defecate on the ground , for which they use special latrines. In the trees, the tree hyraxes hide in tree hollows for protection. In part, the size of a population depends locally on the number of hiding places. The nocturnal and hidden way of life means that tree hyrax are rarely seen.

While other hyrax live in colonies and are very sociable, tree hyrax mainly appear as solitary animals; Occasionally one comes across groups of two or three. These are mostly mother animals with young animals. Every adult individual moves within a territory. These are small and overlap between those of the two sexes. Male animals defend their territories. Rubbing the gland of the back on various objects may serve to mark the boundaries. Characteristic are the nocturnal calls of the tree hyrax, which consist of a series of croak, horn and chopping sounds and can vary significantly between the individual species, but also within the species. They represent an important element of social communication. The calls are made both in the early evening and late at night, indicating that the animals are bimodal . As a sign of excitement, for example in the case of aggression, the hair of the light back spot straightens up. The claw of the rear foot is used as a cleaning claw in body care.

nutrition

The tree hyrax feed on soft vegetable food ( browsing ). The main food consists of leaves , fruits , buds and twigs . The animals mainly look for their food in the trees, but occasionally they also descend on the ground and eat herbs .

Reproduction

Reproduction has hardly been studied so far. It may take place all year round, but it may also be seasonally bound in the case of mountain forest tree hybrids. The gestation period varies between seven and eight months and is therefore extremely long for small animals. One to two young animals are born per litter. Newborns are well developed and completely covered in fur. After 200 days at the latest, the young have reached the size of adult specimens, and sexual maturity occurs after two and a half years. This means that individual development takes a relatively long time. The oldest specimen in human care lived about 14 years.

Systematics

Internal systematics of the recent hyrax according to Maswanganye et al. 2017
  Procaviidae  

 Procavia


   

 Heterohyrax


   

 Dendrohyrax




Template: Klade / Maintenance / Style
John Edward Gray (1800-1875)

The tree hyrax are a genus from the family of hyrax (Procaviidae) with a total of three species . The family is counted to the order of the hyracoidea of ​​the same name in German . The order today consists of three genera, especially in the Paleogene and the early Neogene , but it represented a very diverse group of forms and variants. At that time it consisted of both small and huge representatives that showed numerous different ecological adaptations. Their distribution reached over large parts of Eurasia and Africa . Today's hyrax are limited to guinea pig-like forms, which, with one exception, occur only on the African continent. The tree hyrax represent the most species-rich group among today's snakes. In contrast to their relatives, they live in trees and are solitary and nocturnal.

The following three types are included here:

Another type of fossil has been documented:

In some cases, the mountain forest tree hybrids were not recognized as a valid species, but instead viewed as synonymous with the steppe forest tree hybrids, but numerous systematics both in the past and today lead it to be independent. The three types of tree hyrax can be distinguished both on the basis of external characteristics and also on the basis of their calls. It is possible that another species occurs in western Africa, as, among other things, the calls of the animals of a population in Benin and western Nigeria differ significantly from those of the rainforest tree slipper that is widespread there. There are also significant differences in skull anatomy.

The genus Dendrohyrax was scientifically introduced in 1868 by John Edward Gray . Gray defined it by the longer drawn and flattened skull as well as by the elongated snout, he also noted differences in the tooth structure to Procavia . He referred both the rainforest mountain hyrax and the steppe forest tree hyrax to the genus, but also added the bush hyrax ( Heterohyrax ) to it and thus created Heterohyrax as a subgenus of Dendrohyrax . In 1900 William Lutley Sclater determined the steppe forest tree hyrax as a type . Some scientists also saw the bush hyrax in modern times as a subgenus of the tree hyrax and referred to the low-crowned posterior dentition. In addition to differences in anatomical features, there are also deviations in cytogenetics . As with the hyrax, the chromosome number is 2n = 54, but the set consists of 15 acrocentric, 5 subtelocentric, 5 submetacentric and 1 metacentric pairs of autosomes . The X chromosome is the largest submetacentric chromosome with 5% of the female genome, the Y chromosome is intermediate in size and contains around 2% of the genome.

Tribal history

Hyrax from the Procaviidae family can be detected for the first time in the Upper Miocene . Representatives of the tree hyrax are rarely recorded. Several fragments of the lower jaw, some isolated teeth and various remains of the body skeleton come from Lemudong'o in southwestern Kenya . The finds date to the end of the Upper Miocene around 6 million years ago. They largely agree with the tree slippers, which results among other things from the tooth morphology and the design of the lower jaw, but their fragmented state does not allow a more precise determination. The front part of a skull with a large part of the molar teeth from the Lukeino formation in western Kenya is about the same age . It is assigned to the species Dendrohyrax samueli . Evidence of tree slivers at both sites indicates that the landscapes were densely forested at that time.

Threat and protection

Because of the hidden way of life, nothing is known about exact population numbers. However, it can be assumed that the progressive destruction of the rainforests and the associated fragmentation of suitable habitats also threaten tree hyraxes. The animals are also hunted in parts of their range for food or fur use. The IUCN lists the rainforest and steppe forest tree hybrids as not endangered, but the mountain forest tree hybrids as potentially threatened. All three species are present in protected areas.

literature

  • Hendrik Hoeck: Family Procaviidae (Hyraxes). In: Don E. Wilson and Russell A. Mittermeier (eds.): Handbook of the Mammals of the World. Volume 2: Hooved Mammals. Lynx Edicions, Barcelona 2011, ISBN 978-84-96553-77-4 , pp. 28–47 (pp. 46–47)
  • RM Nowak: Order Hyracoidea. In: Walker's Mammals of the World. 6th edition. Volume II. (RM Nowak). Johns Hopkins University Press, Baltimore, 1999, pp. 1041-1047

Individual evidence

  1. ^ Hendrik Hoeck: Systematics of the Hyracoidea: toward a clarification. In: Duane A. Schlitter (Ed.): Ecology and taxonomy of African small mammals. Bulletin of the Carnegie Museum of Natural History 6, 1978, pp. 146-151
  2. ↑ RM Nowak: Order Hyracoidea. In: Walker's Mammals of the World. 6th edition. Volume II. (RM Nowak). Johns Hopkins University Press, Baltimore, 1999, pp. 1041-1047 online
  3. ↑ a b c d e f g h i Hendrik Hoeck: Family Procaviidae (Hyraxes). In: Don E. Wilson and Russell A. Mittermeier (eds.): Handbook of the Mammals of the World. Volume 2: Hooved Mammals. Lynx Edicions, Barcelona 2011, ISBN 978-84-96553-77-4 , pp. 28–47 (pp. 46–47)
  4. ↑ a b c Martin Pickford: Fossil hyraxes (Hyracoidea: Mammalia) from the Late Miocene and Plio-Pleistocene of Africa, and the phylogeny of the Procaviidae. Palaeontologia africana 41, 2005, pp. 141-161
  5. ↑ a b Herbert Hahn: The family of the Procaviidae. Zeitschrift für Mammaliankunde 9, 1934, pp. 207–358 ( [1] )
  6. ↑ J. du P. Bothma: Recent Hyracoidea (Mammalia) of Southern Africa. Annals of the Transvaal Museum 25, 1967, pp. 117-152
  7. ↑ a b Jeheskel Shoshani, Paulette Bloomer and Erik R. Seiffert: Family Procaviidae Hyraxes. In: Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume I. Introductory Chapters and Afrotheria. Bloomsbury, London, 2013, pp. 150-151
  8. ↑ a b c d e Jos M. Milner and Angela Gaylard: Dendrohyrax arboreus Southern Tree Hyrax (Southern Tree Dassie). In: Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume I. Introductory Chapters and Afrotheria. Bloomsbury, London, 2013, pp. 152-155
  9. ↑ a b c d e Susanne Shultz and Diana Roberts: Dendrohyrax dorsalis Western Tree Hyrax. In: Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume I. Introductory Chapters and Afrotheria. Bloomsbury, London, 2013, pp. 155–157
  10. ↑ a b c d e f Diana Roberts, Elmer Topp-Jørgensen and David Moyer: Dendrohyrax validus Eastern Tree Hyrax. In: Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume I. Introductory Chapters and Afrotheria. Bloomsbury, London, 2013, pp. 158-161
  11. ↑ K. Amanda Maswanganye, Michael J. Cunningham, Nigel C. Bennett, Christian T. Chimimba and Paulette Bloomer: Life on the rocks: Multilocus phylogeography of rock hyrax (Procavia capensis) from southern Africa. Molecular Phylogenetics and Evolution 114, 2017, pp. 49-62
  12. ^ Paulette Bloomer: Genus Dendrohyrax Tree Hyraxes. In: Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume I. Introductory Chapters and Afrotheria. Bloomsbury, London, 2013, p. 152
  13. ↑ Don E. Wilson and DeeAnn M. Reeder: Mammal Species of the World. A taxonomic and geographic Reference. Johns Hopkins University Press, 2005 ( [2] )
  14. ↑ Herbert Hahn: From tree, bush and clip sleepers. Wittenberg, 1959, pp. 1-88
  15. ↑ Simon K. Bearder, John F. Oates, Françoise Dowsett-Lemaire and Robert Dowsett: Evidence of an undescribed form of tree hyrax in the forests of western Nigeria and the Dahomey Gap. Afrotherian Conservation 11, 2015, pp. 2–5.
  16. ^ John Edward Gray: Revision of the species of Hyrax, founded on the specimens in the British Museum. Annals and Magazine of Natural History 4 (1), 1868, pp. 35–52 ( [3] )
  17. ^ William Lutley Sclater: Mammals of South Africa. London, 1900, pp. 1–324 (pp. 308–316) ( [4] )
  18. ^ J. Roche: Systematique du genera Procavia et desmans en general. Mammalia 36, ​​1972, pp. -49
  19. ^ Paulette Prinsloo and TJ Robinson: Comparative cytogenetics of the Hyracoidea: chromosomes of two Hyrax species from South Africa. Journal for Mammalian Science 56, 1991, pp. 331-338
  20. ↑ Martin Pickford and Leslea J. Hlusko: Late Miocene procaviid hyracoids (Hyracoidea: Dendrohyrax) from Lemundon'o, Kenya. Kirtlandia 56, 2007, pp. 106-111
  21. ↑ D. Tab Rasmussen and Mercedes Gutiérrez: Hyracoidea. In: Lars Werdelin and William Joseph Sanders (eds.): Cenozoic Mammals of Africa. University of California Press, Berkeley, London, New York, 2010, pp. 123-145
  22. ^ T. Butynski, H. Hoeck and YA de Jong: Dendrohyrax arboreus. The IUCN Red List of Threatened Species 2015. e.T6409A21282806 ( [5] ); last accessed on December 13, 2017
  23. ^ T. Butynski, F. Dowsett-Lemaire and H. Hoeck: Dendrohyrax dorsalis. The IUCN Red List of Threatened Species 2015. e.T6410A21282601 ( [6] ); last accessed on December 13, 2017
  24. ^ H. Hoeck, F. Rovero, N. Cordeiro, T. Butynski, A. Perkin and T. Jones: Dendrohyrax validus. The IUCN Red List of Threatened Species 2015 :. e.T136599A21288090 ( [7] ); last accessed on December 13, 2017

Web links

Commons : Hyrax ( Dendrohyrax )  - Collection of images, videos and audio files