African palm squirrel
| African palm squirrel | ||||||||||||
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African palm squirrel |
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| Systematics | ||||||||||||
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| Scientific name of the genus | ||||||||||||
| Epixerus | ||||||||||||
| Thomas , 1909 | ||||||||||||
| Scientific name of the species | ||||||||||||
| Epixerus ebii | ||||||||||||
| ( Temminck , 1853) |
The African palm squirrel ( Epixerus ebii ), also known as the great redshank squirrel , is a species from the squirrel family and the only species in the genus Epixerus . With a total length of up to 60 centimeters, the relatively large squirrels live very hidden in several separate rainforest areas in West Africa. Little is known about the way of life of the diurnal and largely solitary squirrels. They feed on seeds and fruits and, in parts of the range, mainly on hard-shelled nuts, which they open with their teeth.
features
The African palm squirrel is a comparatively large species among the African squirrel representatives. The head-trunk length of the animals is about 27 to 30 centimeters, the tail reaches 28 to 30 centimeters, an almost identical length. The weight is around 400 to 650 grams, with the males being heavier than the females. The figure is slender with long legs and a long, bushy tail. The hind feet are noticeably large with a length of about 55 millimeters, the ear length is 20 to 22 millimeters.
The animals have a short fur and a reddish-brown basic color with black and yellowish speckles on the back and a white spot on the throat, the belly is lighter and red-yellow in color. There are no stripes on the sides of the body and the color of the abdomen is sharply demarcated from the color of the back. The bushy gray tail has black and pale gray stripes on the top and a striking pattern of red, black and white to gray bars on the underside. The tail is carried horizontally or hanging down and never rolled up over the back. The head is short and wide with very prominent masticatory muscles. The eyes are big, so are the ears. They extend beyond the forehead and are largely hairless. The females have eight to ten pairs of teats .
Confusion with the common oil palm squirrel ( Protoxerus stangeri ) occurs. The purely tree-living species is, however, somewhat larger and more stocky and more gray in color; the ears are also shorter and do not extend beyond the forehead.
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Differing features can also be found in the comparatively long skull , which measures more than 65 millimeters and has some exclusive features. The bony palate extends well behind the posterior molars and the ratio of the length of the palatine bone to the inter-orbital width is 56 to 65%. The animals have a one in the upper jaw and the lower jaw per half incisor tooth trained incisors (incisive) to which a tooth gap ( diastema follows). This is followed by a premolar and three molars . In total, the animals have a set of 20 teeth.
distribution and habitat
The African palm squirrel occurs in parts of West Africa, where it lives in three separate areas, the respective populations of which form their own subspecies. The nominate form E. ebii ebii lives in the Ivory Coast and Ghana west of the Volta Basin , the subspecies E. ebii jonesi west of it in Sierra Leone , where it is only found in the Bintamane and in the Gola forest, and in Liberia . E. ebii wilsoni occurs separately in Cameroon south of the Sanaga , in Equatorial Guinea and Gabon as well as in a separate area in the Republic of the Congo .
Way of life
The African palm squirrel lives mainly in evergreen rainforest areas and lives in the undergrowth, often in the branches of bamboo palms (genus Raphia ) and similar plants. In Liberia the animals live in wet and humid evergreen and deciduous forests, in Sierra Leone they also occur in mountain forests up to a height of just over 1000 meters. The squirrels are diurnal, but have only a very short period of activity. They also live mostly alone (solitary) and very hidden in the branches of the undergrowth, which makes them difficult to find and observe. In about 80% of the sightings solitary animals were discovered, in the remaining 20% they stayed in pairs or in threes in one place. The territory size of adult animals was determined on the basis of telemetric measurements of individual animals in Gabon and amounts to about 22 hectares for the transmitter-controlled males and about 14 hectares for the females. Within the area, the animals change their positions constantly, the males at around 115 meters per hour and the females at 144 meters per hour.
The animals build their nests in tree hollows with a narrow entrance. You leave the burrow in the morning and return in the afternoon. The animals find their food mainly on the ground, which they search selectively for insects, seeds and fallen fruits. The composition of the food varies seasonally. In Gabon, the hard nuts from Panda oleosa are preferred, which are otherwise mainly used by elephants . The animals split older nuts and younger nuts are gnawed up along the center line and cut in half to get to the core. In regions where the nuts are found, the croissants' feeding places can be identified very well using the shells. To eat the hard nuts in particular, they look for a fixed feeding place in the undergrowth 0.5 to 1.5 meters above the ground, from which they can see potential danger early and are also hidden. Their presence in a forest area can be recognized by the remains of peel piled up below low hanging branches. In addition, the squirrels hoard the nuts at a distance of more than 20 meters from the original trees and thus also contribute to the spread of the species. When threatened, the animals climb into the branches and look for a branch on which they watch out for the potential danger with their tail drooping. When threatened, the animals emit staccato-like tones, which can range from a soft clapping of the incisors in the event of a potential threat to high-pitched shouts in the event of an acute threat. During the alarm calls, they move the drooping tail by jerky movements at the base of the tail, which moves the bushy tail forwards and backwards.
The reproduction of the animals is little researched and there is only one documented litter of two young animals in a nest. In one known case, the mating of a female in oestrus with several males was documented. There is also no information about potential predators and parasites.
Systematics
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Phylogenetic systematics of Protoxerini according to Mercer & Roth 2003
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The African palm squirrel is the only species within the monotypical genus of the African palm squirrel ( Epixerus ). The first scientific description comes from Coenraad Jacob Temminck as Sciurus ebii from 1853, who described the species at the Rijksmuseum van Natuurlijke Historie in Leiden on the basis of individuals from Ghana. In 1909 Oldfield Thomas described the genus Epixerus with the type species Sciurus wilsoni Du Chaillu , 1860, today a synonym for Epixerus ebii . Paul Belloni Du Chaillu, who became world famous as a traveler to Africa, had described Sciurus wilsoni along with other animal species from Equatorial Africa in 1860 in a letter entitled The President in the Chair , which was published in 1866. Thomas differentiated the two then known species E. ebii and E. wilsoni from Protoxerus and Funisciurus due to the properties of the zygomatic arch and the tooth sculpture.
As part of a molecular biological investigation of the phylogeny of the squirrels, the oil palm squirrels ( Protoxerus ) were identified as a sister group of the African palm squirrel, which in turn contrasts within the protoxerini with a taxon made up of redshank squirrels ( Funisciurus ) and African bush squirrels ( Paraxerus ).
Within the species, together with the nominate form, three subspecies are distinguished:
- Epixerus ebii ebii: nominate form; in Ivory Coast and Ghana west of the Volta Basin. The subspecies has a reddish-brown head and a brown back.
- Epixerus ebii jonesi: In Sierra Leone and Liberia. The head and back are colored red.
- Epixerus ebii wilsoni: In Cameroon south of the Sanaga , Equatorial Guinea and Gabon as well as in a separate area in the Republic of the Congo . The head and back are covered and reddish.
Epixerus ebii wilsoni was considered in the past as a separate species under the name Biafra palm squirrel or Wilson palm squirrel ( Epixerus wilsoni Du Chaillu 1860 ), in which case, in addition to the nominate form, another subspecies Epixerus wilsoni mayumbicus is described. Epixerus ebii jonesi was described in 1954 by Robert William Hayman as a new subspecies from Sierra Leone and named after the collector TS Jones, in 1964 this subspecies was also confirmed from Liberia.
The genus Epixerus has not been identified as a fossil; however, the fossil of Kubwaxerus pattersoni from the late Miocene in Kenya, described in 1986, is placed in the related vicinity of the genus.
Hazards and protective measures
Although the population numbers and the development of the total population of this species are not sufficiently known, it is classified by the IUCN Least Concern (not endangered) for the time being. This is justified with the comparatively wide distribution and the assumed large populations . The animals are not frequent and are only rarely encountered, there are only a few preserved specimens in museums and certain sightings are only known sporadically from individual areas.
Deforestation through logging and the conversion of rainforest areas into agricultural areas pose potential dangers for the stocks. Locally, the species is caught in nets by the locals.
supporting documents
- ↑ a b c d e f g h i j k Richard W. Thorington Jr., John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012; Pp. 211-212. ISBN 978-1-4214-0469-1
- ↑ a b c d e f g h i j k l m Louise H. Emmons: Epixerus ebii - Western Palm Squirrel. In: Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume III. Rodents, Hares and Rabbits. Bloomsbury, London 2013, p. 44; ISBN 978-1-4081-2253-2 .
- ↑ a b c d Louise H. Emmons: Genus Exixerus - Western Palm Squirrel In: Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume III. Rodents, Hares and Rabbits. Bloomsbury, London 2013, pp. 45-46; ISBN 978-1-4081-2253-2 .
- ↑ a b c d Epixerus ebii in the IUCN Red List of Threatened Species 2015.1. Posted by: P. Grubb, 2008. Retrieved August 24, 2015.
- ^ Louise H. Emmons: Observations on Litter Size and Development of some African Rainfiorest Squirrels. Biotropica 11 (3), 1980; Pp. 207-213. ( Full text ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. )
- ^ A b John M. Mercer, V. Louise Roth: The Effects of Cenozoic Global Change on Squirrel Phylogeny. Science 299, 2003; Pp. 1568-1572; doi : 10.1126 / science.1079705
- ↑ a b Epixerus ebii In: Don E. Wilson , DeeAnn M. Reeder (Ed.): Mammal Species of the World. A taxonomic and geographic Reference. 2 volumes. 3. Edition. Johns Hopkins University Press, Baltimore MD 2005, ISBN 0-8018-8221-4 .
- ^ Coenraad Jacob Temminck : Esquisses Zoologiques Sur la Côte de Guiné le Partie, les Mammifères. EJ Brill, Leiden 1853; P. 129. ( digitized version )
- ↑ a b Oldfield Thomas : The Generic Arrangement of the African Squirrels. The Annals and magazine of natural history, series 8 (3) 1909; Pp. 467-475; First description of Epixerus on p. 472. ( digitized version )
- ^ Paul Belloni Du Chaillu : The President in the Chair. Proceedings of the Boston Society of Natural History Vol. 7, 1866; Pp. 358-364. ( Reprint Forgotten Books, 2013 ( Memento of September 24, 2015 in the Internet Archive )); First description of Sciurus wilsoni on p. 364.
- ^ Robert William Hayman : IV. — A new west African squirrel. Annals and Magazine of Natural History: Series 12, Volume 7 (73), 1954; P. 16. doi : 10.1080 / 00222935408651686
- ^ Hans-Jürg Kuhn : Epixerus ebii jonesi in Liberia. Bonn zoological contributions, issue 3/4, 1964. ( full text )
- ↑ a b Epixerus Thomas, 1909 (Western Palm Squirrels). In: Ara Monadjem , Peter J. Taylor , Christiane Denys , Fenton PD Cotterill : Rodents of Sub-Saharan Africa. A biogeographic and taxonomic synthesis. De Gruyter, Berlin, Boston 2015; Pp. 66-70. ISBN 978-3-11-030191-5 (accessed from De Gruyter Online).
- ↑ Richard L. Cifelli, Alfreda K. Ibui, Louis L. Jacobs, Richard W. Thorington Jr .: A Giant Tree Squirrel from the Late Miocene of Kenya. Journal of Mammalogy , May 15, 1986; Pp. 274-283. doi : 10.2307 / 1380880
literature
- Richard W. Thorington Jr., John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012; Pp. 211-212. ISBN 978-1-4214-0469-1
- Louise H. Emmons: Genus Exixerus - Western Palm Squirrel and Epixerus ebii - Western Palm Squirrel. In: Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume III. Rodents, Hares and Rabbits. Bloomsbury, London 2013, pp. 44-46; ISBN 978-1-4081-2253-2 .
- Epixerus Thomas, 1909 (Western Palm Squirrels). In: Ara Monadjem, Peter J. Taylor, Christiane Denys, Fenton PD Cotterill: Rodents of Sub-Saharan Africa. A biogeographic and taxonomic synthesis. De Gruyter, Berlin, Boston 2015; Pp. 66-70. ISBN 978-3-11-030191-5 (accessed online from De Gruyter ).
Web links
- Epixerus ebii inthe IUCN Red List of Threatened Species 2015.1. Posted by: P. Grubb, 2008. Retrieved August 24, 2015.
