Atlas squirrel

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Atlas squirrel
Atlas squirrel on Fuerteventura

Atlas squirrel on Fuerteventura

Systematics
Subordination : Squirrel relatives (Sciuromorpha)
Family : Squirrel (Sciuridae)
Subfamily : Ground Squirrel (Xerinae)
Tribe : Bristle cone (xerini)
Genre : Atlantoxerus
Type : Atlas squirrel
Scientific name
Atlantoxerus getulus
( Linnaeus , 1758)

The Barbary ground squirrel , North African ground squirrel or Berber croissants ( Atlantoxerus getulus ) is in the Atlas Mountains in Morocco and Algeria widespread type of ground squirrel . It is the only recent species of the genus Atlantoxerus , which has also been detected in several fossil species since the Miocene . The medium-sized type of croissant is characterized by a clear striped pattern on the back. It lives on the ground and feeds mainly on plants, primarily seeds and fruits.

The animals were introduced to the island of Fuerteventura in the 1960s and are now considered a pest for agriculture and a threat to native animals and plants, but are very popular with tourists who enjoy their presence.

features

general characteristics

The atlas squirrel is a medium-sized squirrel and reaches a head-torso length of 16.5 to 23.0 and an average of about 19.4 centimeters, plus a tail with a length of 9.0 to 19.0, an average of 15.8 Centimeters. The hind foot length is 41 to 52, on average 46 millimeters, and the ear length 12 to 18, on average 15 millimeters. The weight is about 250 grams. The coat is short with hair about three to five millimeters long and rough. It is pale yellow to gray-brown on the back and consists of hairs that are light brown or sand-colored at the base and sometimes have a black tip. In the area of ​​the spine and trunk there are also isolated, longer black hairs. On each flank, a clearly visible white stripe runs from the shoulders to the rear of the trunk, which does not reach the base of the tail and is flanked on both sides by slightly darker fur. There is also a less noticeable light stripe that runs along the middle back and is shorter than the side stripes. However, this stripe can also be indistinctly recognizable or completely absent. The ventral side is only thinly covered with white or gray-white hair.

Atlas squirrel with a piece of banana on Fuerteventura

The head is rounded with a blunt snout and strong masticatory muscles and its color corresponds to that of the back. The ears are small without tufts of hair and the eyes have a light eye ring. The nostrils are narrow and hairless and can be closed. The legs are somewhat elongated compared to related species; they also correspond in color to the top. The front feet have four long toes that terminate in sharp claws, the fifth toe is reduced to a small remainder without a claw. The hind feet have bare soles and five narrow toes with long and slightly curved claws, the fifth toe being shortened here. The tail has a moderate length, which is about 80% of the length of the head and torso. It is bushy and consists of hair about 25 to 30 millimeters long. The hair is creamy white with two distinct, wide black bands and a white tip, giving the tail a pattern of light and dark stripes, each of which ends in white. The females have a total of four pairs of teats . The young animals differ from the adult animals, in addition to their size, primarily through their significantly softer fur.

The atlas squirrel is similar to the African bristle squirrel , but its fur is not quite as bristly. There is a risk of confusion with the striped bristle squirrel ( Xerus erythropus ), whose distribution area only overlaps with that of the atlas squirrel in the Souss plain in southwestern Morocco. The fur of this species is coarser and brown, it also has only one short light stripe on each side of the body. In addition, the muzzle is longer with a clearly pointed nose.

Features of the skull and skeleton

1 · 0 · 2 · 3  =  22
1 · 0 · 1 · 3
Atlas squirrel tooth formula

The skull of the animals has a total length of 38.4 to 50.0, on average 45.9 millimeters, in the area of ​​the zygomatic arches the width is 23.6 to 30.8, on average 27.9 millimeters. It is less angular than that of other Palearctic ground squirrels and has a clearly pronounced crest . 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 two premolars in the upper jaw and one premolar and three molars in the lower jaw . In total, the animals have a set of 22 teeth. The upper incisors have an indistinct pit. The upper first premolar (P 3 ) is very small and pin-shaped, it can sometimes be missing. The molars have a slightly concave surface with clear transverse ridges. The bony palate is comparatively long at around 62% of the length of the skull, but ends well before the third molar.

The penis bone (baculum) is long and narrow and ends in a spoon-like widening with a small ridge on the top and a larger one on the bottom that bends to the left.

Genetic traits

The genome of the species consists of a diploid set of chromosomes with 2n = 68 chromosomes.

distribution and habitat

Distribution areas of the Atlas squirrel (red: natural distribution area, yellow: introduced)

Atlas squirrels are endemic in the Atlas Mountains in northwestern Africa from the territory of Western Sahara via Morocco to northwest Algeria in the Ksour Mountains. The animals have the main distribution in the Middle and High Atlas south of Agadir in Morocco as well as in the Anti-Atlas and the northern edge of Western Sahara south of Saguia el Hamra . The altitude distribution extends from the seashore to heights of 4165 meters in the Atlas.

The animals were carried on men to Spain belonging Canary Islands introduced the African Atlantic coast. They have lived on Fuerteventura since 1965 and are omnipresent there. In Gran Canaria they were in 1996 and on Lanzarote introduced in 2006, now however it is removed.

Atlas squirrels live in dry and stony habitats in rocky regions up to the desert. They prefer open habitats with a vegetation of scattered trees and bushes, especially juniper ( spec Juniperus. ) Sandarakbäumen ( Tetraclinis articulata ) and argan trees ( Argania spinosa ), however, avoid vegetation-free areas and forests. They also live in various agricultural areas and use stone walls that offer hiding places. In contrast, the animals do not occur in irrigated areas and fields.

Way of life

Atlas squirrel looking for food
Atlas squirrel

Much information about the way of life of the Atlas squirrel comes from observations on Fuerteventura, but probably also applies to the animals in the natural range. They are diurnal and live primarily on the ground. The diet is predominantly herbivorous ; plant-based foods usually make up more than 75% of the total diet. The main part of the diet in the natural range is made up of seeds, nuts and fruits from the argan tree, the wild olive tree ( Olea europaea ), the pistachio ( Pistacia atlantica ), juniper and the sandarac tree. In addition, there are grasses and roots, grain in agricultural areas and, more rarely, insects and edible remains on garbage dumps in the area of ​​human settlements. On Fuerteventura and also in the natural area of ​​distribution, numerous other plants are added as potential sources of food, especially the fruits and plant parts of the also imported opuntia , spurge ( Euphorbia ), atractylis , mesembryanthemum , blue-green tobacco ( Nicotiana glauca ), salt herbs ( Salsola ), pounders ( Emex spinosa ), squill ( Scilla ) and branchy affodill ( Asphodelus ramosus ). Especially with asparagus ( Asparagus ), opuntia, red color ( Rubia ), buckthorn ( Lycium ) and Prunus species, the animals prefer the fruits and actively contribute to the spread of the seeds. In addition, there is animal food, including land snails or small birds such as the desert bullfinch ( Bucanetes githagineus ) as well as eggs and nestlings on Fuerteventura.

Atlas squirrels have two main phases in their activity in which they look for food. These are in the morning between 7 and 11 a.m. with a main activity around 9 a.m. and in the afternoon between 2 and 6 p.m., especially at 3 p.m. The animals are very sensitive to temperature fluctuations and drops, the optimal temperature for their activity is around 24 ° C. You have a body temperature of 36 - 39 ° C, which can drop to 25 ° C if the temperature is too low or rise by 1 to 1.5 ° C if you overheat; in either case, these temperature changes can be fatal. During the very hot lunchtime and at night, the animals hide in their burrows that they create in the ground under rocks or between stones in scree, whereby the entrances are often covered by vegetation. In the southern part of the distribution area, permanent water availability is required, which means that the species cannot penetrate very far into desert habitats. In higher areas of the Atlas Mountains, there is a significant reduction in activity in winter, regardless of a blanket of snow. However , the animals do not hibernate .

Male atlas squirrel on a rock as an observer
Two atlas squirrels

Atlas squirrels live together in family groups and small colonies. The smallest unit of the colony is a single female with her young. However, two females can also use a burrow together with their offspring if there is enough space. These pairs of two females can also come together before the breeding season and form a common nest. A loose colony is formed from several of these family groups, although more complex compositions with several lactating females, their offspring and a male animal can occur. However, the composition of the groups can change quickly, especially during the mating season, with individual animals also migrating to neighboring colonies. Within the colony, atlas squirrels, like some other ground squirrels, show a watchful behavior to protect themselves from predators. The adult animals of a colony take turns after about an hour and observe the surroundings from raised stones or walls in order to identify potential threats. Stones and stone walls are also used to protect the entrances and as hiding places as well as for thermoregulation .

During the mating season, males willing to mate often take an elevated position on rocks and call for females, while at the same time monitoring their territory. These rocks are characterized by the male droppings. The specific breeding time varies regionally and can take place on Fuerteventura up to three times a year with an interval of four months each, individual females can be mated by several males. For example, pregnant females were observed in the east of Morocco in April while the young had already been born in the Sahara and had already been weaned in the Western Sahara. At higher altitudes, the young are not born until July. The litter consists of up to four young animals, on Fuerteventura up to nine young animals have been observed in one litter. The young animals weigh about 6 to 9.5 grams at birth, they leave their maternal structure after five to six weeks. The maximum age of wild animals is not known; in captivity, up to five years of life are documented.

The main predators of the Atlas squirrels are diurnal birds of prey, more rarely owls, as well as foxes and crawling cats . In Fuerteventura, house cats are the greatest threat, alongside the buzzard ( Buteo buteo ), the common raven ( Corvus corax ) and the kestrel ( Falco tinnunculus ). Several parasites have been documented, with the louse Neohematopinus pectinifer being known as a carrier of spirochetes , which can cause relapsing fever in humans. There are also acanthamoebae and numerous parasitic worms ( Brachylaima , Catenotaenia chabaudi , Dermatoxys getula , Protospirura muricola , Syphacia pallaryi , Trichostrongylus ). Brachylaima was only detected on Fuerteventura and is attributed to the consumption of infected snails, Dermatoxys getula and Syphacia pallaryi have been identified in both the continental and island populations.

Atlas squirrel as a neozoon

Atlas squirrels are very trusting and popular with tourists on Fuerteventura
Warning “do not feed the croissants” on Fuerteventura; The Atlas squirrel is considered a pest for local agriculture and a threat to native plants and animals on the island.

The atlas squirrel was introduced to several Canary Islands as a neozoon , i.e. as a non-native species . While they were probably successfully removed on Gran Canaria (introduced in 1996) and on Lanzarote (introduced in 2006), they have established stable populations on Fuerteventura . Here they were introduced as pets in 1965 and were able to establish themselves in the wild, after which they were established, partly actively by humans, all over the island. Today, the animals are considered pests for domestic agriculture and a threat to domestic plants and animals, but on the other hand they are also a tourist attraction and are described accordingly in numerous travel guides.

In addition to the house rat ( Rattus rattus ), the brown rat ( Rattus norvegicus ) and the house mouse ( Mus musculus domesticus ), the atlas squirrel is one of four introduced rodent species in the Canary Islands, whereby it is the only type of squirrel. The atlas squirrel is common in Fuerteventura and can be found in almost all habitats, with population densities being lower in the sandy areas than in the more rocky, dry regions of the island. The effects of the atlas squirrel on the ecological balance of the island are diverse. In addition to the loss of agricultural yields, significant effects on the vegetation composition and distribution of neophytes , an influence on the composition of the predators on the island, the introduction of parasites and diseases as well as direct effects on seabird populations and endemic snail species were documented.

The competition for resources with domestic and other introduced species, especially food, as well as the effects on local fauna and flora have been the focus of the investigations so far. In 2008 López-Darias & Nogales examined above all the competition between the Atlas squirrel and the native Eastern Canarian lizard ( Gallotia atlantica ) and the wild rabbit ( Oryctolagus cuniculus ), which was also introduced . Since juicy and fleshy fruits play a role as an essential source of food and water on the dry island, the use of these plant parts is relevant for all herbivores. They were able to prove that the preferred food plants of the species differed significantly; while fruits of shrubby madder ( Rubia fruticosa are eaten mainly by the Lizard), consume Barbary ground squirrel mainly the fruits of Lycium intricatum and also introduced in Fuerteventura Opuntienart Opuntia maxima (on the current state a synonym for Opuntia ficus-indica ). Asparagus pastorianus is eaten equally by all fruit consumers. While the native lizards were originally primarily responsible for the distribution of the seeds of native species, this effect is now reduced by the introduced species, at the same time the atlas squirrels in particular lead to a rapid spread of the opuntia on the island by distributing their seeds and thus lead to a change in the island's vegetation.

Using modeling of climatic factors, the invasion potential of the atlas squirrel was also calculated for other regions. The temperature and humidity conditions were particularly considered. As a result, it was found that the climatic habitat conditions in the natural range would allow a potential distribution of the species over the entire Maghreb region, the entire Canary Islands and large areas of the Western European Mediterranean region. Among the Canary Islands, El Hierro , Lanzarote and Gran Canaria in particular offer suitable living conditions. Based on the habitat factors of the animals that have already been introduced to Fuerteventura, only Lanzarote and Gran Canaria would be ideal. Ecological factors that positively influence distribution and settlement were also examined using the animals on Fuerteventura. An essential factor here was the availability of stones and stone walls, which offer hiding places from predators as well as support with thermoregulation and sun protection. In addition, piles of stones and walls play a major role in the social behavior of the animals. In addition to these structures, sandy areas for nest building and the availability of plants for food also play a central role in the choice of habitat.

Systematics

Carl von Linné (painted by Alexander Roslin in 1775) described the Atlas squirrel in the 10th edition of his Systema Naturae .

The atlas squirrel is classified as the only recent species within the monotypical genus Atlantoxerus . The first scientific description comes from Carl von Linné as Sciurus getulus from 1758, who described the species in the 10th edition of his Systema Naturae as one of seven species of the squirrel genus Sciurus . The species thus belongs to the Eurasian squirrel ( S. vulgaris ), the American fox squirrel S. niger and S. cinereus , the European flying squirrel ( S. volans ), the striped chipmunk ( S. striatus ) and the non-assignable species Sciurus flavus one of the oldest types of modern scientific binomial description that Linnaeus introduced with this work. As terra typica , that is, as a description of origin, Linné only gave “in Africa”, this was narrowed down in 1911 by Oldfield Thomas to “Barbary” and thus to the home of the Berbers and in 1932 by Ángel Cabrera Latorre to Agadir in the south of Morocco.

The species was later assigned to the genus Xerus together with several other species . 1893 of the Swiss zoologist and paleontologist examined Charles Immanuel Forsyth Major dental structures of several extant and extinct croissants and divided the genus Xerus based thereon into several sub-genres, where he next Atlantoxerus with the Barbary ground squirrel as the type species, the current genera Protoxerus and Paraxerus erstbeschrieb as subgenera. Oldfield Thomas elevated Atlantoxerus to the genus rank in 1909, also on the basis of tooth features, with the atlas squirrel as the only species.

Phylogenetic systematics of the Xerini
 Xerini  


 Atlas squirrel ( Atlantoxerus )


   

 African ground squirrel ( Xerus )



   

Ground squirrel ( Spermophilopsis leptodactylus )



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Together with the African bristle squirrel and the ground squirrel ( Spermophilopsis leptodactylus ), the atlas squirrel is assigned to the tribe Xerini . On the basis of features of the lower jaw and molecular biological features of the DNA , a sister group relationship of Atlantoxerus and Xerus is likely. In this case, the ground squirrel, as a sister species of these two genera, would be regarded as a common taxon . The Xerini are also probably the most basic group within the ground squirrels (Xerinae). The distribution of the two genera Atlantoxerus and Xerus , which only occur in Africa today , is traced back to a single settlement by common ancestors of both genera.

Apart from the nominate form Atlantoxerus getulus getulus, no further subspecies are distinguished within the species .

Fossil history

The genus Atlantoxerus has been known to be fossilized since the early Miocene in what is now China and in the Middle Miocene on the Arabian Peninsula . It diversified and quickly spread over large parts of East Asia, Southern Europe and North Africa in the following period. For the Upper Miocene, at least four species are known that lived in Spain, France, Algeria, Morocco and Rhodes .

The atlas squirrel itself was first recorded in Morocco in the early to middle Pleistocene , although the origin of the species is unknown and it cannot be safely associated with any of the previously extinct species of the Maghreb . A close relationship with the species Atlantoxerus androveri , originally found in Spain , was suggested, but not finally clarified.

Status, threat and protection

The atlas squirrel is very common, especially in the lowland areas and lower mountain ranges of the distribution area, and it can be found regularly up to an altitude of around 2000 meters. Above this level, stocks decrease sharply. There is also a sharp decrease in populations in the eastern part of the distribution area, although local populations exist in the desert regions . Overall, it is assumed that there are natural population fluctuations.

The Atlas squirrel is classified as Least Concern by the International Union for Conservation of Nature and Natural Resources (IUCN) . This is justified with the comparatively wide distribution and frequent occurrence of the animals. They occur in different habitats and are accordingly adaptable, even in habitats that have been changed and disturbed by humans. The species was settled outside of its natural range and is considered a pest in the new habitats . There are no risks to the existence of the atlas squirrel.

supporting documents

  1. a b c d e f g h i j k l m Stéphane Aulagnier, Patrick Gouat, Michel Thévenot: Atlantoxerus getulus - Barbary 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. 43-44; ISBN 978-1-4081-2253-2 .
  2. a b c d e Stéphane Aulagnier: Genus Atlantoxerus - Barbary 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, p. 42; ISBN 978-1-4081-2253-2 .
  3. a b c d e Atlantoxerus getulus in the Red List of Threatened Species of the IUCN 2013.2. Posted by: S. Aulagnier, 2008. Retrieved March 1, 2016.
  4. 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. 200-201. ISBN 978-1-4214-0469-1
  5. a b c Marta López-Darias, Manuel Nogales: Effects of the invasive Barbary ground squirrel (Atlantoxerus getulus) on seed dispersal systems of insular xeric environments. Journal of Arid Environments 72, 2008; Pp. 926-939. doi : 10.1016 / j.jaridenv.2007.12.006
  6. Rafael Barrientos, Francisco Valera, Andrés Barbosa, Carmen M. Carrillo, Eulalia Moreno: Plasticity of nest-site selection in the trumpeter finch: A comparison between two different habitats. Acta Oecologica 35, 2009; Pp. 499-506. doi : 10.1016 / j.actao.2009.03.005
  7. a b M. López-Darias, JM Lobo: Factors affecting invasive species abundance: the Barbary ground squirrel on Fuerteventura Island, Spain. Zoological Studies 47 (3), 2008; Pp. 268-281. ( Full text preprint ).
  8. a b c Marta López-Darias, Alexis Ribas, Carlos Feliú: Helminth parasites in native and invasive mammal populations: comparative study on the Barbary ground squirrel Atlantoxerus getulus L. (Rodentia, Sciuridae) in Morocco and the Canary Islands. Acta Parasitologica 53 (3), 2008; p. 296-301. doi : 10.2478 / s11686-008-0036-5
  9. ^ A b A. Traveset, M. Nogales, JA Alcover, JD Delgado, M. López-Darias, D. Godoy, JM Igual, P. Bover: A review on the effects of alien rodents in the Balearic (Western Mediterranean Sea) and Canary Islands (Eastern Atlantic Ocean). Bioligal Invasions 11, 2009; Pp. 1653-1670. ( Full text ( Memento of the original from March 5, 2016 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this note. ) @1@ 2Template: Webachiv / IABot / izt.ciens.ucv.ve
  10. a b Marta López-Darias, Jorge M. Lobo, Patrick Gouat: Predicting potential distributions of invasive species: the exotic Barbary ground squirrel in the Canarian archipelago and the west Mediterranean region. Biological Invasions 10, 2008; Pp. 1027-1040. doi : 10.1007 / s10530-007-9181-2
  11. ^ Edward F. Anderson : The great cactus lexicon. Eugen Ulmer KG, Stuttgart 2005 (translated by Urs Eggli), p. 459. ISBN 3-8001-4573-1
  12. a b c d e Atlantoxerus getulus 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 .
  13. ^ Carl von Linné : Systema naturae. 10th edition, 1758; Volume 1, p. 64 ( digitized version ).
  14. Charles Immanuel Forsyth Major : On some Miocene squirrels, with remarks on the dentition and classification of the Sciurinae. Proceedings of the Zoological Society of London, 1893; Pp. 179–216, Taxonomy on p. 189. ( digitized version ).
  15. Oldfield Thomas : The Generic Arrangement of the African Squirrels. Annals and Magazine of Natural History 3 Series 8, 1909; Pp. 467-475. ( Digitized version ).
  16. a b c J.M. Mercer, VL Roth VL: The effects of Cenozoic global change on squirrel phylogeny. Science 299 (5622), 2003; Pp. 1568-1572. doi : 10.1126 / science.1079705 , ( full text )
  17. a b c Isaac Casanovas-Vilar, Jan van Dam: Conservatism and Adaptability during Squirrel Radiation: What Is Mandible Shape Telling Us? PLOS One, April 4, 2013. doi : 10.1371 / journal.pone.0061298
  18. Scott J. Steppan, Brian L. Storz, Robert S. Hoffmann: Nuclear DNA phylogeny of the squirrels (Mammalia: Rodentia) and the evolution of arboreality from c-myc and RAG1. Molecular Phylogenetics and Evolution 30, 2004; Pp. 703-719. ( Full text )
  19. MD Herron, JM Waterman, CL Parkinson: Phylogeny and historical biogeography of African ground squirrels: the role of climate change in the evolution of Xerus. Molecular Ecology 14, 2005; Pp. 2773-2788. doi : 10.1111 / j.1365-294X.2005.02630.x

literature

  • Richard W. Thorington Jr., John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012; Pp. 200-201. ISBN 978-1-4214-0469-1
  • Stéphane Aulagnier, Patrick Gouat, Michel Thévenot: Atlantoxerus getulus - Barbary 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. 43-44; ISBN 978-1-4081-2253-2 .
  • Stéphane Aulagnier: Genus Atlantoxerus - Barbary 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, p. 42; ISBN 978-1-4081-2253-2 .

Web links

Commons : Atlas Squirrel  - Collection of images, videos and audio files
This article was added to the list of excellent articles on May 12, 2016 in this version .