Red squirrel
| Red squirrel | ||||||||||||
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Common red squirrel |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Tamiasciurus | ||||||||||||
| Trouessart , 1880 |
The red squirrels ( Tamiasciurus ), also known as chickarees in the USA , are a genus of squirrels that are now counted among the tree squirrels .
features
Despite the name, the red squirrels are not red. They are very variable in color, the upper side is beige-brown, olive-brown or black-brown; it often becomes darker in winter than in summer. The underside is white in the common red squirrel and brown in the Douglas squirrel. A blackish longitudinal stripe runs along the flank, but in many individuals it hardly stands out from the underlying coat color and is then invisible. The head body length is 20 cm, plus about 12 cm tail. The weight is 150 to 300 grams.
Way of life
Red squirrels are most commonly found in coniferous forests , where they are among the most common mammals. They are less common in the deciduous and mixed forests dominated by gray squirrels . Red squirrels are diurnal and move around the ground more often than squirrels. They build different nests: in summer a nest in a fork of a branch is enough for them, while they tend to pad a hole in a tree trunk for the winter - abandoned woodpecker holes are often used for this purpose. In colder parts of their range, they also live in underground tunnels where they spend the winter; in doing so, they take over the gait systems of ground squirrels and stump-tailed squirrels . Red squirrels do not hibernate , but in very cold weather they sometimes stay in their caves for several days, which are equipped with food supplies.
The main food of the red squirrel is the cones of the conifers. These are loosened from the tree and placed in the pantries. Some of these storage chambers can hold up to 160 pins. In addition to cones, red squirrels eat all sorts of animal and plant substances, including nuts, fruits, bark, mushrooms, bird eggs and young birds.
Red squirrels live solitary and defend a territory that is centered in their pantries. Couples only come together briefly to mate. This happens in late winter; in the warmer parts of the range there is also a second mating season in summer. The females give birth to four to six young after a gestation period of 35 days. These are suckled for up to eight weeks and become self-employed after 18 weeks. The lifespan of red squirrels in the wild is up to seven years.
Threat and protection
The red squirrels seem to play a major role in the expansion of the conifers by carrying the seed scales of the cones far around. Because the common red squirrel is so common, it is hardly threatened by fur hunting. In Canada, around 2 million red squirrels are killed annually in order to use their fur for fur processing. However, things are bad for a subspecies of the common red squirrel , the Mount Graham red squirrel ( Tamiasciurus hudsonicus grahamensis ), which lives isolated from the other populations in Arizona . There are only 200 individuals of this subspecies, which is why the IUCN has it under the status of "critically endangered".
Systematics
The position of the red squirrel within the squirrel was always problematic. At first they were united in a common tribe due to the similarities of the external genitals with the Chinese red squirrels . The relationship between the two groups was questioned early on. Various authors placed the red squirrels in close proximity to the bristle squirrels and ground squirrels because of other morphological features . Since 2003, the cladistic analyzes by Mercer and Roth as well as Herron, Castoe and Parkinson have shown that the red squirrels are very close to the tree squirrels . Carleton and Musser place them accordingly in this tribe.
The allocation of species and subspecies can vary depending on the source; a distinction is usually made between three species:
- Common red squirrel ( Tamiasciurus hudsonicus ), Canada , Alaska , Rocky Mountains , Northeastern USA
- Douglas squirrel ( Tamiasciurus douglasii ), Cascade Mountains and Sierra Nevada
- Southwestern red squirrel ( Tamiasciurus Fremdonti ) found in parts of Utah, Arizona, Texas, and New Mexico
The Mearns squirrel ( Tamiasciurus mearnsi ) from northern Baja California is also partially regarded as an independent species, but according to the current system it is a subspecies of the Douglas squirrel today, however, as a separate species.
The term "red squirrel " can lead to confusion, as there are also the Chinese red squirrels and the Amazon red squirrels belonging to the genus of squirrels . The Eurasian squirrel is also known in English as the red squirrel ; in the USA , however, it means the common red squirrel.
supporting documents
- ↑ a b c J.L. Koprowski, EA Goldstein, KR Bennett, C. Pereira Mendes: Tamiasciurus. In: Don E. Wilson, TE Lacher, Jr., Russell A. Mittermeier (Eds.): Handbook of the Mammals of the World: Lagomorphs and Rodents 1. (HMW, Volume 6) Lynx Edicions, Barcelona 2016, p. 739 -740, ISBN 978-84-941892-3-4 .
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 .
- John M. Mercer, V. Louise Roth: The effects of Cenozoic global change on squirrel phylogeny. In: Science . Vol. 299, No. 5612, 2003, pp. 1568-1572, doi : 10.1126 / science.1079705 .
- Matthew D. Herron, Todd A. Castoe, Christopher L. Parkinson: Sciurid phylogeny and the paraphyly of Holarctic ground squirrels (Spermophilus). In: Molecular Phylogenetics and Evolution. Vol. 31, No. 3, 2004, ISSN 1055-7903 , pp. 1015-1030, doi : 10.1016 / j.ympev.2003.09.015 .
- Michael D. Carleton, Guy G. Musser: Order Rodentia. In: Don E. Wilson , DeeAnn M. Reeder (Eds.): 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 , pp. 745-1600.
- JL Koprowski, EA Goldstein, KR Bennett, C. Pereira Mendes: Tamiasciurus. In: Don E. Wilson, TE Lacher, Jr., Russell A. Mittermeier (Eds.): Handbook of the Mammals of the World: Lagomorphs and Rodents 1. (HMW, Volume 6) Lynx Edicions, Barcelona 2016, p. 739 -740, ISBN 978-84-941892-3-4 .
