Plain bristle cone
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Plain bristle squirrel ( Xerus rutilus ) |
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| Xerus rutilus | ||||||||||||
| ( Cretzschmar , 1828) |
The plain bristle squirrel or stripless bristle squirrel ( Xerus rutilus ) is a type of squirrel from the genus of the African bristle squirrel ( Xerus ). It occurs in the arid regions of East Africa.
features
The plain-bristle squirrel reaches an average head-trunk length of 26.1 to 23.7 centimeters, the tail is 14.5 to 20.5 centimeters long. The weight is about 135 to 440 grams. The rear foot length is 50 to 60 millimeters, the ear length 12 to 17 millimeters. It is a medium-sized ground squirrel with a rough, short fur on the back. The back can be colored from pale tan through yellowish brown to strong reddish brown and it has light and black speckles. The back hairs are short with a length of five to six millimeters, they are dark red-brown at the base and have a sand-colored or black tip. Animals in drier areas are usually lighter and paler in color than those in wetter areas. There is no bright side stripe on the flanks, which distinguishes it from other species of the genus. The peritoneum is white to whitish yellow and paler than the back fur, the belly is only thinly haired. The head has a conspicuous light ring under the eyes, the ears are small. The top of the feet is whitish, but in some individuals it can also be reddish brown. The tail reaches a length that corresponds to about 85% of the head-trunk length. The hairs of the tail are about 40 millimeters long and banded, they are white at the base, black-brown in the middle and red-brown or white at the tip. The females have two paired teats (0 + 0 + 1 + 1 = 4). The genome consists of a diploid chromosome set of 2n = 38 chromosomes.
| 1 | · | 0 | · | 2 | · | 3 | = 22 |
| 1 | · | 0 | · | 1 | · | 3 |
The skull has a total length of 47.1 to 53.7 millimeters and a width of about 27.0 to 32.3 millimeters. Like all species of the genus has the type in the upper jaw half per one to a incisor tooth formed incisor (incisor) to which a tooth gap ( diastema follows). This is followed by two premolars and three molars . The teeth in the lower jaw correspond to those in the upper jaw, but only with a premolar. In total, the animals have a set of 22 teeth. The bony palate ends well before the front edge of the last molars.
The sizing Borstenhörnchen can with that in the western parts of the range sympatrically occurring Striped Borstenhörnchen ( Xerus erythropus ) to be confused. However, this is significantly larger and has a noticeable side stripe. An additional premolar may be present in the dentition in some individuals of this type.
distribution
The plain bristle squirrel occurs in the arid regions of East Africa. The distribution area extends from northeastern Tanzania and Uganda via Kenya and Ethiopia east of the rift valley to the north to South Sudan and Sudan , to Eritrea and Djibouti as well as to Somalia .
Way of life
The plain-bristle squirrel lives in the semi - deserts and savannah areas of its distribution area, which are characterized by thorn bushes and grasses . In parts of Kenya in the area of Lake Turkana , the species lives in the bushes of the toothbrush tree ( Salvadora persica ). The species can also live very well in modified habitats and is also found in agricultural areas.
The animals are diurnal and live terrestrially on the ground, they leave their burrows in the early morning and warm up in the sun for about 30 minutes immediately after leaving. They feed primarily herbivore on seeds, leaves, flowers as well as soft fruits and especially the fruits of the African baobab tree . There are also insects. Seeds and parts of plants make up at least 50% of the stomach's content. The animals set up several feed stores in which they hoard seeds and other food. Plain bristle squirrels usually appear as individual animals or in small family groups consisting of a mother and a few young animals. Adult males can coexist with one or more females. A building can be inhabited by one to six individuals. The animals avoid each other at the food sources, as a rule males behave in a dominant or aggressive manner towards the females. Communication takes place via various sounds, including a warning sound from the females and young animals, which is used when a male comes. The underground burrows are separate from one another and are usually located below bushes and the entrances are on the trunks of the bushes, and burrows are often built in termite nests . The building usually has two to six entrances. In addition to their own burrows, the animals occasionally also use the burrows of other animals, sometimes together with the striped bristle squirrel ( Xerus erythropus ). With an area of around 7 hectares, the territories of the males are significantly larger than those of the females, which are usually around 1.4 hectares. The territories clearly overlap with each other, including those of animals of the same sex. Aggressive territorial behavior has not yet been observed, but there is a clear hierarchy of dominance between the animals in overlapping areas. The animals are very well adapted to high temperatures and seek the shade of rocks or plants to avoid direct sun. In addition, they press their sparsely hairy belly onto the cool ground to cool off.
The mating season of the plain-bristle squirrels extends over the entire year. The mating behavior of the animals begins with the males approaching the females, whereby the males spread the hair of the tail and carry the tail over the head. The females usually move back, calling softly, hit the floor with their tails and press the anal region onto the floor. When the male gets closer, the female lies down on the ground and rolls on her side, allowing the male to sniff her genital area. The male mounts and then mates with the female. The females give birth to one or two young per litter in the underground burrow, which is usually on the edge of the territory of the female. After the young have left the mother's den, the female withdraws to a burrow in the center of the territory. The lifespan of the animals in the wild is unknown; one male lived to be more than 6 years old in captivity.
About potential predators No information is available as ectoparasites which was previously flea Synosternus somalicus and tick Haemaphysalis calarata documented as endoparasite is Catenotaenia geosciuri known.
Systematics
The plain bristle squirrel is classified as an independent species within the genus of the African bristle squirrel ( Xerus ), which consists of four species. The first scientific description comes from the zoologist Philipp Jakob Cretzschmar from 1828, who described the animals as Sciurus rutilus based on individuals from eastern Abyssinia . They probably came from the Massaua region in what is now Eritrea.
Within the species, eight subspecies are distinguished together with the nominate form :
- Xerus rutilus rutilus : nominate form; The subspecies occurs in the Massaua region in Eritrea to the east of Sudan and the north of Ethiopia.
- Xerus rutilus dabagala : The subspecies lives in northern Somalia and is characterized by a yellowish area in the dorsal fur.
- Xerus rutilus dorsalis : The form occurs from western Kenya to eastern Uganda and South Sudan. She has a dark head, a light yellow tint on the sides of the body and a white tint on the abdomen and feet.
- Xerus rutilus intensus : The subspecies living in Ethiopia differs from Xerus rutilus dabagala in the lack of the yellow back area.
- Xerus rutilus massaicus : The subspecies lives in the Olorgesailie basin north of Magadi in Kenya. The color of the subspecies is white-yellowish-pink with black speckles, the sides of the body have no black spots and are reddish-pink. The ventral side is yellowish-white with a lighter color around the chin, neck and lower sides of the body. The red tint is paler than that of Xerus rutilus rufifrons .
- Xerus rutilus rufifrons : The subspecies occurs in the northern Uaso Nyiro in Kenya. The shape is clearly reddish in color, especially on the face and head, the fur on the back is yellowish.
- Xerus rutilus saturatus : The subspecies occurs in southeastern Kenya and northeastern Tanzania. The feet are red-brown and the tail is indistinctly curled in red.
- Xerus rutilus stephanicus : The subspecies lives in Ethiopia, Somalia and in the northeast knee. The shape is pale yellow and pink in color and has a red-brown top of the head. It only has a slight black speckle.
Status, threat and protection
The plain bristle squirrel is listed by the International Union for Conservation of Nature and Natural Resources (IUCN) as not endangered (“least concern”). This is justified by the comparatively large distribution area, the assumed large populations of animals in their habitat, which also includes several protected areas, as well as the good adaptability to habitat changes. There are no known threats to the species' existence.
supporting documents
- ↑ a b c d e f g h i j k l m n o Jane M. Waterman: Xerus rutilus, Unstriped Ground Squirrel (Pallid Ground 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. 100-101; ISBN 978-1-4081-2253-2 .
- ↑ a b c d e f g h Richard W. Thorington Jr. , John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012; Pp. 208-210. ISBN 978-1-4214-0469-1
- ↑ Jane M. Waterman: Genus Xerus, Ground Squirrels. 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. 93-94; ISBN 978-1-4081-2253-2 .
- ↑ a b Xerus rutilus in the IUCN 2016-2 Red List of Endangered Species . Posted by: P. Grubb, N. Oguge, 2008. Retrieved September 20, 2016.
- ↑ Xerus rutilus . In: Don E. Wilson , DeeAnn M. Reeder (Eds.): 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 .
literature
- Richard W. Thorington Jr. , John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012; Pp. 208-210; ISBN 978-1-4214-0469-1 .
- Jane M. Waterman: Xerus rutilus, Unstriped Ground Squirrel (Pallid Ground 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. 100-101; ISBN 978-1-4081-2253-2 .
Web links
- Xerus rutilus inthe IUCN 2016-2 Red List of Threatened Species . Posted by: P. Grubb, N. Oguge, 2008. Retrieved September 20, 2016.