Antelope pebble
| Antelope pebble | ||||||||||||
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Harris antelope pebble |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Ammospermophilus | ||||||||||||
| Merriam , 1892 |
The antelope pebbles ( Ammospermophilus ) are a genus of ground squirrels . They look very similar to the ground squirrel and have long been counted in the same genus. The view that they should constitute a separate genus is supported by several molecular genetic studies.
features
With a head body length of 14 to 16 cm, a 6 to 9 cm long tail and a weight of 100 to 140 g, antelope ground squirrels are even smaller and more delicate than real ground squirrels. They are colored in different shades of brown depending on the species. All species are characterized by a white vertical stripe, which can be seen on both sides of the body.
distribution and habitat
The habitat are arid areas in the southwest of North America. These are deserts, semi-deserts, and plains with little grass cover. While one species occurs north to Oregon , the distribution area of the other species is concentrated in California , New Mexico , Texas , Arizona and northwestern Mexico .
Way of life
Antelope pebbles build corridors in which they hide at night. During the day they come out and look for seeds, fruits and roots, and exceptionally for insects and carrion. Often food is stowed in the cheek pouches and brought into the burrow.
The colonies of the antelope pebble comprise six to eight animals that live together in a strict hierarchy. The females have their young after a gestation period of 30 days. The size of the litter varies between five and fourteen. Life expectancy is low. Because of the large number of predators (including birds of prey , kit foxes , bobcats , coyotes , silver badgers and rattlesnakes ), few antelope gnats are older than a year. In captivity, however, they can live up to six years.
The animals have a special mechanism for thermoregulation that enables them to look for food outside their caves even on very hot days. They alternate approximately every hour between the hot desert environment and their cave construction. In their caves, which are cool relative to their surroundings, they give off the heat stored in their bodies. This saves you from other metabolically more complex mechanisms for thermoregulation.
Systematics
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Phylogenetic systematics of the Marmotini according to Herron et al. 2004
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The antelope pebbles are a genus of squirrels , where they are assigned to the ground squirrels (Xerinae) and therein the real ground squirrels (Xerini). The first scientific description of the genus was by Clinton Hart Merriam in 1892.
In 2004 they were confirmed as a monophyletic group in a molecular biological investigation and identified together with the genus Notocitellus as a sister group of the entire Marmotini .
There are five types, all of which are very similar to one another:
- Harris' antelope pebble ( Ammospermophilus harrisii ), Arizona , Sonora
- White-tailed antelope pebble ( Ammospermophilus leucurus ), western North America
- Texas antelope pebble ( Ammospermophilus interpres ), Texas , New Mexico , Coahuila , Chihuahua , Durango
- Espiritu Santo antelope pebble ( Ammospermophilus insularis ), Isla Espíritu Santo (island off the coast of Baja California )
- Nelson's antelope pebble ( Ammospermophilus nelsoni ), central California
Others
The Nelson antelope pebble is listed as threatened by the IUCN . Its distribution area covers only 3900 km² and is endangered by agricultural development, laid out rat poison, and oil and natural gas fields. The other four species are not considered endangered. Although they are not overly common, they are one of those animals in the deserts of North America that an attentive observer can hardly miss.
The name "antelope squirrel" is a relationship with the pronghorn ago that than in the US antelope is known. This shows its white tail on the run, just like the antelope pebble.
literature
- Ronald M. Nowak: Walker's Mammals of the World. 2 volumes. 6th edition. Johns Hopkins University Press, Baltimore MD et al. 1999, ISBN 0-8018-5789-9 .
Web links
Individual evidence
- ^ A b 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. ( doi : 10.1016 / j.ympev.2003.09.015 , full text , PMID 15120398 )