Rio Grande Ground Squirrel
| Rio Grande Ground Squirrel | ||||||||||||
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| Ictidomys parvidens | ||||||||||||
| ( Mearns , 1896) |
The Rio Grande ground squirrel ( Ictidomys parvidens , Syn . : Spermophilus parvidens , Spermophilus mexicanus parvidens ) is a species of squirrel from the genus Ictidomys . He lives in northern Mexico as well as southern New Mexico and western Texas .
features
The Rio Grande ground squirrel reaches a head-trunk length of about 21.6 to 32.5 centimeters, the tail is about 8.0 to 13.0 centimeters long and is therefore less than half as long as the rest of the body. The weight is 90 to 210 grams. The animals have an olive-gray to light brown back coloration with a pattern of nine interrupted rows of white to light-sand-colored spots that run from the neck to the base of the tail. The muzzle and chin are yellowish to ocher or cinnamon, the animals also have a noticeable light eye ring. The belly and the flanks are light sand-colored to white. The tail is grayish black and interspersed with the sand-colored tint of the belly.
In its appearance, the Rio Grande ground squirrel is very similar to the Mexican ground squirrel ( Ictidomys mexicanus ) in central Mexico, to which it has long been considered a subspecies.
distribution
The Rio Grande ground squirrel occurs in northern Mexico in the states of Coahuila , Nuevo León , Tamaulipas , Durango and Zacatecas as well as in southern New Mexico and western Texas .
Way of life
The Rio Grande ground squirrel is diurnal and lives in dry areas in the grasslands and in the grass and bushes landscapes of the distribution area; it can also occur in anthropogenic grass areas such as cemeteries or golf courses. It is omnivorous and the diet consists mainly of different parts of plants such as leaves, sprouts, flowers and seeds of grass, herbs, bushes and cacti. In addition, insects and other animal foods such as small vertebrates are added when these are available.
The animals live like other ground squirrels on the ground and in underground burrows. The main building of the animals for rearing young and wintering is usually about 1.5 meters deep and can consist of several chambers and networked corridors with several exits. In addition, the animals use several short escape burrows. In favorable habitats, the animals can form colonies from several burrows, but the social connection is poor. The movement areas of the animals are small and are usually less than 90 meters and territories of the individual animals can overlap. In mild climates, the animals are active throughout winter, but in most regions they hibernate for up to seven months, starting from late July to September. The adult males begin their winter dormancy in August at the latest, the females and young animals a little later in September or even in October. The males usually wake up in March two to four weeks before the females and prepare for mating by increasing their body weight through intensive food consumption. The mating season begins after the females wake up in spring and lasts around 30 to 70 days until April. After a gestation period of 28 to 30 days, the females give birth to a litter of two to ten, on average five to six, young animals. The young animals leave the den for the first time in late May to August, and in August they are weaned from the mother.
The mortality of the young animals in the first year is 70%, the survival rate of the adult animals is relatively high at 53 to 63%. The main predators for the Rio Grande ground squirrel are likely cats, dogs, martens, birds of prey and snakes. In the event of danger, the animals emit a shrill alarm call.
Systematics
The Rio Grande ground squirrel is classified as an independent species within the genus Ictidomys , which consists of three species. It was regularly assigned to the Mexican ground squirrel as a subspecies and accordingly not viewed as an independent species. The Mexican ground squirrel and its subspecies have long been classified as part of the ground squirrel and within the subgenus Ictidomys , but after a comprehensive molecular biological investigation it was assigned to the now independent genus Ictidomys . The first scientific description comes from the American naturalist Edgar Alexander Mearns from 1896. He described the species on the basis of individuals at Fort Clark in Kinney County in Texas.
Apart from the nominate form, no subspecies are distinguished within the species .
Status, threat and protection
The Rio Grande ground squirrel is not listed by the International Union for Conservation of Nature and Natural Resources (IUCN), but is considered together with the Mexican ground squirrel and classified as Least Concern. This is justified by the comparatively large distribution area, the assumed large population numbers and the ability to use numerous different habitats. There are no known potential risks to the company's existence.
supporting documents
- ↑ 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. 269-270. ISBN 978-1-4214-0469-1
- ↑ a b Spermophilus (Ictidomys) mexicanus parvidens 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 .
- ↑ 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
- ↑ Carole J. Young, J. Knox Jones, Jr .: Spermophilus mexicanus. Mammalian Species 164, 1982; Pp. 1-4. ( Full text ( Memento of the original from March 16, 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. )
- ↑ a b c Ictidomys mexicanus 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. Accessed May 23, 2016.
literature
- Richard W. Thorington Jr., John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012; Pp. 269-270. ISBN 978-1-4214-0469-1
- Carole J. Young, J. Knox Jones, Jr .: Spermophilus mexicanus. Mammalian Species 164, 1982; Pp. 1-4. ( Full text ; treats the Rio Grande ground squirrel as a subspecies)