Rock gobbler
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Rock Ground Squirrel ( Otospermophilus variegatus utah ) |
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| Scientific name | ||||||||||||
| Otospermophilus variegatus | ||||||||||||
| ( Erxleben , 1777) |
The (or) rock gnome ( Otospermophilus variegatus , syn .: Spermophilus variegatus ) is a rodent from the squirrel family (Sciuridae). He lives in North America, the southwestern United States, and northern and central Mexico . In this distribution area, the rock giraffe is the largest species of the real ground squirrel .
features
The rock ground squirrel is the largest species of the genus Otospermophilus and the largest of the real ground squirrels in its range. It reaches a body length of 430 to 540 millimeters and weighs between 600 and 850 grams; the males are slightly larger than the females. The rock squirrel has a large head and large eyes. The ears are at the top of the head and are much longer than they are wide. The neck is relatively long and thick. The front limbs are shorter than the rear.
The tail is long and bushy, but less pronounced than that of the tree squirrel . The fur on the back is patterned in black and white and pale yellow and brown. The color of the fur is very different within and between the populations. The underside is different and varies between grayish white or pink yellow-brown and cinnamon-colored yellow-brown. The head is yellow-brown to almost black.
The rock ground squirrel has over-eye windows ( foramen supraorbitale ) and a grayish color on the sides of the head, which the ring- tailed ground squirrel and the tropical ground squirrel do not have. In these, the over-eye windows are closed and the sides of the head are pale orange-brown or pale yellow-brown. The Californian ground squirrel and the Baja California ground squirrel have, in contrast to the rock ground squirrel , whitish neck sides and shoulders. Furthermore, one of which clearly defined the distribution area of Felsenziesels the California and Baja California Ziesels: the former comes in California and Nevada , west of Felsenziesels before and the latter is only in Baja California to find (Baja California). In addition, the rock ground squirrel differs from the California ground squirrel in fur color; the latter is smaller and has a shorter tail compared to the body length.
Way of life
As the name suggests, rock gunners prefer regions with rocky subsoil. If this is not available in natural form, the animals mainly stay near old buildings, stone walls or other artificial structures. Rock gunners are found mainly in the meadows of the highlands and in the oak-covered prairie ( savannah ). They are rarely found in open plains , deserts and higher montane forests. Rock goblets can be found up to heights of 2900 meters.
Rock gunners can live solitary or in groups. In regions with a higher population density, they form colonies in which social behavior can be observed, such as the role of a dominant male or the joint consumption of food. In regions with a lower population density, social behavior is much less pronounced. Males and females live separately and usually only come into contact during the mating season.
habitation
Rock gunners live in caves, which are very often located on steep slopes and near dry river beds under rock ledges, trees or bushes. In addition, there are often an above-average number of pieces of wood around the building that can serve as vantage points. In northern regions, the entrances are mainly on slopes that point south or west so that the snow melts more quickly in spring. In more southerly regions the entrances are mainly in a northerly direction so that less strong solar radiation can get into the building in summer.
The reason that rocky peasants build their homes on steeper slopes is possibly that they are better drained during the summer during the rainy season . The proximity to dry river beds brings a greater supply of food.
nutrition
The rock gobbler spends most of the day, especially in the morning, gathering food, which it finds both on the ground and in the trees. Some of it is consumed right at the place of discovery. Often they take it to lookouts and eat it there. In addition, they collect a lot in their cheek pouches and bury it in small holes in the ground. The cheek pouches of the rock gnome are very large. In the filled pockets of one animal, 62 acorns of the Gambel oak were counted.
The rock goblet eats green plants, fruits, nuts , grains, berries , roots, flowers, cacti , invertebrates such as grasshoppers , beetles and earthworms , as well as small vertebrates such as young turkeys and other birds.
Reproduction
The rock squirrel lives polygynously . When several animals live together in a colony, the dominant male within the group defends his right to mate the females in sometimes fierce fights. In regions in which the population of the rock squirrel is lower and the animals predominantly live individually, their territory increases considerably during the mating season from 0.7 to 1.6 hectares to around eight hectares.
The length and the beginning of the mating season of the rocky pebble depend on the geographical latitude and the altitude at which the animals live. In southeastern Arizona , males become fertile between late March and early July and females between mid-May and mid-June. Mating takes place there between mid-April and early July and, like in other regions, depends on the rainy season in summer. The young can leave the burrow shortly after the start of the rainy season, when the vegetation is growing and the food supply is better.
Mating takes about four weeks in Utah and about six weeks in central Texas . In New Mexico , it can take up to 14 weeks. The male first performs several physical rituals with the female. Then the female retreats into the burrow while the male goes hunting. The actual mating act takes place in the building.
The female is pregnant for about 30 days. It has between three and nine young (an average of 4.8) who weigh an average of 7.8 grams. They are nursed by the mother for about two weeks and remain in the burrow for another six weeks before going outside for the first time. For about three days, the cubs, which now weigh about 100 grams, are still fed by their mother. The boys stay in the same territory as their mother and use their den for up to 14 weeks after leaving it for the first time. They are fertile after a year or two.
Enemy avoidance
In addition to birds of prey and other predators such as bobcat , gray fox , raccoon and silver badger , snakes are natural enemies of the rocky pebble . Since rock gnomes live sympatric with poisonous snakes, they have developed a pronounced behavior towards snakes. If there is a snake nearby, approach it and assume a stretched position. Then they wag their tails and throw pieces of wood or small stones. Sometimes they attack the snake too. Rock gnomes are immune to the venom of rattlesnakes.
As a further measure to avoid enemies, the rock gnome uses numerous vantage points such as rocks or tree stumps, where food is often taken or where they can rest. If an enemy approaches, the animals warn each other. Rock gobs give off a strong musky scent from their anal glands when disturbed.
distribution
The rock squirrel is common in the southwestern United States and northern Mexico. In the United States, the species occurs in most of New Mexico and Arizona to the Edwards Plateau and Pecos River (Trans-Pecos-Texas) in the east and as far as California in the west. To the north it can be found in Colorado , especially west of the Front Range , in most of Utah to eastern Nevada . In Mexico, the distribution area extends almost over the entire north to the middle of the country to Puebla , Colima , Guerrero , México and Morelos except for the lowlands in the east.
Systematics
The rock ground squirrel is a species of the genus Otospermophilus within the ground squirrel . The first description was in 1777 by Johann Christian Polycarp Erxleben . The genus has long been classified as part of the ground squirrel and within the subgenus Otospermophilus , but after a comprehensive molecular biological investigation, this was considered as an independent genus together with several other genera.
There are eight subspecies:
- Spermophilus variegatus buckleyi Slack , 1861 (central and southwest Texas )
- Spermophilus variegatus couchii Baird , 1855 (northeastern Mexico , especially Coahuila )
- Spermophilus variegatus grammurus ( Say , 1823) (mainly Arizona , New Mexico and Colorado and northwestern Mexico)
- Spermophilus variegatus robustus ( Durrant & Hansen , 1954) (mainly eastern Nevada )
- Spermophilus variegatus rupestris ( Allen , 1903) (northern Mexico, mainly Durango , Sinaloa and southern part of Chihuahua )
- Spermophilus variegatus tularosae ( Benson , 1932) (central New Mexico)
- Spermophilus variegatus utah ( Merriam , 1903) (mainly Utah )
- Spermophilus variegatus variegatus ( Erxleben , 1777) (Central Mexico)
Rock gnome and man
Rock gurns are sometimes viewed as a nuisance because they occasionally damage crops. Although the losses were not significant, they were killed for it. Rock gunners carry numerous ectoparasites , which are known to be carriers of tularemia , Rocky Mountains spotted fever and brucellosis , among others . After the Red List of IUCN the rock squirrel is deemed not at risk.
supporting documents
- ↑ a b Richard W. Thorington Jr., John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012; Pp. 296-298. ISBN 978-1-4214-0469-1
- ↑ 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
swell
- Spermophilus variegatus - Mammalian Species (PDF file; 1.02 MB)
- Spermophilus variegatus on the Animal Diversity Web
Web links
- Rock Squirrel - Spermophilus variegatus (English)
- Otospermophilus variegatus in the endangered Red List species the IUCN 2008. Posted by: Linzey, AV & NatureServe, 1996. Accessed on March 18 of 2009.