Round-tailed ground squirrel
| Round-tailed ground squirrel | ||||||||||||
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Round-tailed ground squirrel ( Xerospermophilus tereticaudus ) |
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| Xerospermophilus tereticaudus | ||||||||||||
| ( Baird , 1858) |
The round-tailed ground squirrel ( Xerospermophilus tereticaudus , syn .: Spermophilus tereticaudus ) is a species of squirrel from the genus Xerospermophilus . It occurs from southeastern California and southern Nevada through western Arizona to the Mexican states of Sonora and Baja California .
features
The round-tailed squirrel reaches a head-trunk length of about 20.4 to 27.8 centimeters, the tail is about 60 to 112 millimeters long and is thus significantly shorter than the rest of the body. The weight is 110 to 170 grams. The back of the animals is pale-gray to pink-sand-colored with no recognizable markings. The sides of the body, abdomen and legs are lighter pale sand colored. The cheeks are white to pale clay. The slightly rounded tail is the same color as the back, the underside is a little lighter in color from sand to cinnamon. It is rounded towards the end and can have a dark to black tip.
distribution
The round-tailed ground squirrel occurs from southeastern California and southern Nevada through western Arizona to the Mexican states of Sonora and Baja California .
Way of life
The round-tailed ground squirrel is diurnal and lives in dry, sandy desert areas, which are mainly characterized by mesquite bushes (genus Prosopis ) and the creosote bush ( Larrea tridentata ). It is omnivorous and, like other ground squirrels, its food consists primarily of different parts of plants such as buds, flowers, leaves and fruits as well as seeds and insects. They collect the food in their cheek pouches . The animals are very heat-tolerant and still look for food at 45 ° C, occasionally using small shaded areas or the entrances to the burrows for cooling.
The animals live like other ground squirrels on the ground and in underground burrows. The activity of the animals lasts for the whole year in some regions, but they usually hibernate for several months. In the adult females this hibernation lasts from September to March at the most, in the males it can last from May to January. The wintering can take place together in the same building or individually. The adult males awaken well before the females and leave their burrows to form and defend their territories. The activity areas of the males and females are about the same size and cover an average of 0.3 hectares. The building is relatively inconspicuous without grave heaps or mounds, it is often under bushes or in the area of stones.
The reproduction is coordinated with the winter rains of the Mohave and Sonora deserts, the mating season begins after the females have awakened in March. The gestation period lasts 26 to 35 days and pregnant females can be found from March to June. Then the females give birth to a litter of one to 13, an average of 4.9 to 6.5 young animals in the burrow. The animals are polygamous and multiple matings and paternity are common and can lead to an increase in the number of young animals. After mating with a female, the males leave a "mating plug" in the form of a secretion from accessory sex glands in the vagina , which is supposed to prevent fertilization by sperm from other males. Weaning takes place after five to six weeks, and the young animals leave the den for the first time one to two weeks beforehand. The males spread more widely than the females, who often stay in the maternal burrow or nearby. The animals reach sexual maturity after ten to eleven months.
The most important predators for the round-tailed ground squirrel are birds of prey and snakes as well as cats, dogs and martens. When threatened, the animals retreat into their burrows and generally give a high-pitched whistling sound and, with birds of prey, a series of chirps, with snakes they drum their hind feet on the ground.
Systematics
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Phylogenetic system of the genus Xerospermophilus according to Fernández 2012
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The round-tailed ground squirrel is classified as an independent species within the genus Xerospermophilus , which consists of four species. The species has long been classified as part of the ground squirrel and within the subgenus Xerospermophilus , but after a comprehensive molecular biological investigation it was assigned to the now independent genus Xerospermophilus . The first scientific description comes from the American zoologist Spencer Fullerton Baird from 1893. He described the species as Spermophilus tereticaudus on the basis of individuals from the region around what was then Fort Yuma, now in Imperial County in California on the border with Arizona and Mexico.
In a phylogenetic study with a focus on the relationship of the Perote ground squirrel, the round-tailed ground squirrel was identified as a sister species of the Mojave ground squirrel and compared to the other two species of the genus, the Perote ground squirrel and the spotted ground squirrel. Within the species, four subspecies are distinguished together with the nominate form :
- Xerospermophilus tereticaudus tereticaudus : nominate form; occurs in southern Nevada and California as well as on the northern peninsula of Baja California.
- Xerospermophilus tereticaudus apricus : occurs isolated in the Valle de la Trinidad at higher elevations between the mountain ranges in northern Baja California. The shape is a little darker and more brown than the nominate shape.
- Xerospermophilus tereticaudus chlorus : occurs in the Coachella Valley in southern California. The color is a monotonous gray without a pink tinge.
- Xerospermophilus tereticaudus neglectus : occurs in southern and western Arizona and northwestern Sonora. It is a little darker than the nominate form and has a slightly shorter tail.
Status, threat and protection
The round-tailed squirrel is classified by the International Union for Conservation of Nature and Natural Resources (IUCN) as not endangered (least concern). This is justified by the relatively large distribution area, the assumed large populations and the ability to colonize a wide range of habitats.
Potential endangerments for the species are not known. In some regions there is a threat in the conversion of desert areas into settlements and agricultural areas, with Xerospermophilus tereticaudus chlorus in southern California being particularly affected. The animals are not hunted, but are fought regionally as pests with poison.
supporting documents
- ↑ a b c d e f g h i j k l m Richard W. Thorington Jr., John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012; Pp. 370-371. ISBN 978-1-4214-0469-1
- ^ Karen E. Munroe, John L. Koprowski: Copulatory Plugs of Round-Tailed Ground Squirrels (Xerospermophilus tereticaudus). The Southwestern Naturalist 57 (2), 2012; Pp. 208-210. doi : 10.1894 / 0038-4909-57.2.208 .
- ↑ a b Kristina A. Ernest, Michael A. Mares: Spermophilus tereticaudus. Mammalian Species 274, 1987; Pp. 1-9. ( Full text )
- ^ A b Jesús A. Fernández: Phylogenetics and biogeography of the microendemic rodent Xerospermophilus perotensis (Perote ground squirrel) in the Oriental Basin of Mexico. Journal of Mammalogy 93 (6), 2012; Pp. 1431-1439. doi : 10.1644 / 11-MAMM-A-409.1
- ↑ Matthew D. Herron, Todd A. Castoe, Christopher L. Parkinson: Sciurid phylogeny and the paraphyly of holarctic ground squirrels (Spermophilus). Molecular Phylogenetics and Evolution 31, 2004; Pp. 1015-1030. ( Full text , PMID 15120398 )
- ↑ Kristofer M. Helgen, F. Russell Cole, Lauren E. Helgen, Don E. Wilson: Generic Revision in the holarctic ground squirrels genus Spermophilus. Journal of Mammalogy 90 (2), 2009; Pp. 270-305. doi : 10.1644 / 07-MAMM-A-309.1
- ↑ a b Spermophilus (Xerospermipilus) tereticaudus 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 .
- ↑ a b Xerospermophilus tereticaudus in the IUCN Red List of Threatened Species 2015.4. Posted by: AV Linzey, R. Timm, ST Álvarez-Castañeda, I. Castro-Arellano, T. Lacher, 2008. Retrieved May 17, 2016.
literature
- Richard W. Thorington Jr., John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012; Pp. 370-371. ISBN 978-1-4214-0469-1
- Kristina A. Ernest, Michael A. Mares: Spermophilus tereticaudus. Mammalian Species 274, 1987; Pp. 1-9. ( Full text )
Web links
- Xerospermophilus tereticaudus inthe IUCN Red List of Threatened Species 2015.4. Posted by: AV Linzey, R. Timm, ST Álvarez-Castañeda, I. Castro-Arellano, T. Lacher, 2008. Retrieved May 17, 2016.