Belding ground squirrel

Belding ground squirrel
	Belding ground squirrel ( Spermophilus beldingi ) in Yosemite National Park , California . The animal stands upright in the guard position.
Systematics
Subordination :	Squirrel relatives (Sciuromorpha)
Family :	Squirrel (Sciuridae)
Subfamily :	Ground Squirrel (Xerinae)
Tribe :	Real ground squirrels (Marmotini)
Genre :	Urocitellus
Type :	Belding ground squirrel
Scientific name
	Urocitellus beldingi
	( Merriam , 1888)

The Belding ground squirrel ( Urocitellus beldingi , syn .: Spermophilus beldingi ) is a species of ground squirrel that belongs to the squirrel family within the rodent order . It lives in the mountains in the western United States and is mainly plant-based. Most of the knowledge about Belding ground squirrel is based on over 20 years of observations of a population at Tioga Pass in Yosemite National Park .

features

The Belding ground squirrel is a medium-sized ground squirrel. The animals usually reach a total length of 23 to 30 centimeters, males are slightly longer than females, but the difference is in the centimeter range. Belding ground squirrels weigh an average of around 360 grams (males) or 300 grams (females), extreme values for males are 300 to 450 grams, for females 230 to 400 grams. The fur is gray to cinnamon brown. On the middle of the back there is a broad brown-red longitudinal band, which in the subspecies S. b. beldingi most clearly and in S. b. creber is weakest. The headstock is also brownish red. The comparatively short tail is 4.4 to 7.6 inches long, bushy and has a reddish hue. Relatively small ears and extremities are characteristic of the species.

As with the closest related species (subgenus Spermophilus ) within the ground squirrel, the molars of the Belding ground squirrel are particularly high-crowned (hypsodont). The tooth formula is I 1/1, C 0/0, P 2/1, M 3/3, they have a total of 22 teeth.

distribution and habitat

Habitat of the Belding ground squirrel

Belding ground squirrels inhabit the mountains in the western United States. The distribution extends from eastern Oregon south to northeast California and east to southeast Idaho and northwest Utah . They populate areas from 500 meters above sea level. Sometimes they occur at great heights, for example at the Tioga Pass in Yosemite National Park in the southern Sierra Nevada at over 3000 meters above sea level.

The species lives in montane and submontane meadows and pastures. It evidently needs access to open water or to succulent vegetation. Belding ground squirrels avoid forests and rocky areas. In Oregon, where Belding's ground squirrel occurs sympathetically with Columbia ground squirrel ( Spermophilus columbianus ), the former seem to inhabit somewhat more humid habitats. Both species are apparently in direct competition with each other, which is evident from the fact that they colonize a wider range of habitats in areas in which they occur without the other species. The Belding ground squirrel is probably in minimal competition with other species of ground squirrel, such as the California ground squirrel ( Spermophilus beecheyi ) and the gold-coated ground squirrel ( Spermophilus lateralis ), as they differ significantly in their choice of habitat and food.

Way of life

nutrition

Belding ground squirrels, like all ground squirrels, live primarily on vegetable food. They eat flowers, seeds, nuts, roots, mushrooms and grass, but also insects and other invertebrates, bird eggs and carrion. Young small mammals are rarely actively hunted; males often eat the young of their own species.

Hibernation

The hibernation of the Belding ground squirrel lasts about seven to eight months from October to April / May, during which time one third of the adult animals and two thirds of the juvenile animals perish. The causes are mostly exhausted fat stores, death occurs through freezing and starvation. Furthermore, some specimens of silver badgers and coyotes are excavated and killed.

Social behavior

Female Belding ground squirrels live in groups in an area (although each female has its own burrow), males are solitary animals.

Female Belding ground squirrels show the phenomenon of nepotism , the preference for related conspecifics (females stay together with relatives as they rarely migrate from the area of birth after weaning). When building a nest, there are seldom conflicts with close relatives, and females with relatives have an easier time building a nest than females without related animals nearby. Very close relatives also share the litter territory (the area where young animals are born) as well as food sources and hiding places. In addition, closely related Belding ground squirrels drive unrelated females out of the area they inhabit and warn each other of predators. Females that are very closely related help each other to defend their territories.

During the gestation period and lactation , however, related animals often exclude themselves from their territory as there is a risk of infanticide . Even if an area is only unguarded for a short time, foreign females and young males often invade the area and kill the young. As a motivation for killing the young, males usually have the food that the hunt offers them: They always eat the killed young. Females rarely consume the infanticide victims; usually they kill the young of other females after killing their own litter, regardless of whether it was killed by conspecifics or by enemies. So far, the motivation for the infanticide in females is not clear. After killing their own litter, females usually leave the apparently unsafe burrow and look for a safe place; If possible, the young animals there are killed by the invading females. The closely related and closely living females can track down and drive away such Belding ground squirrels more quickly. When a female is out foraging with pups, the den is often defended by a related animal. In the Belding ground squirrel, nepotism is an efficient strategy for better chances of survival and higher reproduction rates.

Reproduction and development

Two young Belding ground squirrels

One week after waking up from hibernation, females are ready to mate. Despite being ready to conceive in just one afternoon, they mate with three to eight different males. According to genetic analysis, two thirds of all litters come from several males. The genetic make-up of the male that mated first is always dominant, but the genetic make-up of four different males could be identified in one litter.

The males' recruitment consists mainly in defending a small territory. In the presence of females ready to conceive, fierce fighting often ensues between the males, which almost always result in injuries. In these fights, weight and experience are usually decisive. Females willing to mate usually stay close to the males who win the fights most often. Successful males mate with up to 13 females in one season, but more than half of the males copulate only once per season or not at all.

After mating, the female builds a litter box. Most burrows with a litter box (including the corridors) are five to eight meters long and are 30 to 60 centimeters below the surface of the earth. The nest building usually has several entrances in order to ensure escape opportunities when predators such as snakes enter. The nest is padded with grass; to do this, the female brings up to 50 loads of grass into the nest. After a gestation period of 23-28 days, 1-11, on average about 5 young, are born. After weaning at the age of 26–31 days, they leave the burrow for the first time. Males usually migrate shortly thereafter, but females often linger near the birth den for life.

Males reach an average age of two to three years, females around three to four years. The life expectancy of males is lower, as they are injured when fighting with conspecifics and because they are more exposed to threats due to their greater migratory activities.

Enemy avoidance

The females living in company warn each other of enemies with a varied arsenal of calls. If silver badgers, coyotes or weasels appear in the populated area, some females stand on their hind legs and emit clipped, trilling-like sounds. When birds of prey appear , monotonous, high-pitched whistles are emitted in quick succession. Due to the warning sounds, all ground squirrels flee within earshot to their burrows and hiding spots. However, there is an increased risk for the warning animal, since it is particularly noticeable for predators. The risk that different females take is therefore different. Elderly, resident, and nursing females are most likely to warn of predators, as there are many related females in their vicinity. Immigrant specimens of both sexes call much less often.

Systematics

The Belding ground squirrel is a species of the genus Urocitellus within the ground squirrel . The genus has long been classified as part of the ground squirrel and within the subgenus Urocitellus , but after a comprehensive molecular biological investigation, this was considered as an independent genus together with several other genera. The first scientific description was in 1888 by Clinton Hart Merriam as Spermophilus beldingi using animals from Donner in Placer County , California.

It probably split off from the closest North American relative of this genus in the late Pleistocene . However, there are no fossil finds of Urocitellus beldingi .

There are currently three subspecies.

U. b. beldingi : Central Eastern California, western Nevada (the type specimen comes from Placer County in California)
U. b. creber : Northern and central Nevada, southwestern Idaho, southeastern Oregon and northwestern Utah (the type specimen comes from the valley of the Reese River in Nevada)
U. b. oregonus : eastern Oregon, northwestern Nevada, northeastern California (originally described as a separate species based on an animal from the Klamath basin in California)

At the border of the distribution areas of U. b. oregonus and U. b. creber in southeast Oregon and northwest Nevada seem to have smooth transitions. Between the known distribution areas of U. b. oregonus and U. b. beldingi gapes a 40 km wide gap in California, but transitional forms should also occur here.

Status, threat and protection

The Idaho ground squirrel is classified by the International Union for Conservation of Nature and Natural Resources (IUCN) as least concern. This is justified by the frequent occurrence and the lack of population-endangering risks for the species. Regionally, the species is regarded as a pest and it is therefore persecuted in many parts of the distribution area, mainly through the laying of poison baits, which then also other, rarer animal species kill.

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, ISBN 978-1-4214-0469-1 , pp. 296-298 .

↑ 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 Stephen H. Jenkins, Bruce D. Eshelman: Spermophilus beldingi. In: Mammalian Species . No. 221, 1984, pp. 1-8, full text as pdf .

↑ Urocitellus beldingi in the IUCN Red List of Threatened Species 2016.1. Posted by: AV Linzey & NatureServe (G. Hammerson), 2008. Retrieved July 14, 2016.

literature

Richard W. Thorington Jr. , John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012, ISBN 978-1-4214-0469-1 , pp. 296-298 .
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, full text as pdf ( Memento from June 2, 2010 in the Internet Archive ).
Stephen H. Jenkins, Bruce D. Eshelman: Spermophilus beldingi. In: Mammalian Species . No. 221, 1984, pp. 1-8, full text as pdf .
Jill M. Mateo: Early Auditory Experience and the Ontogeny of Alarm-Call Discrimination in Belding's Ground Squirrels (Spermophilus beldingi). In: Journal of Comparative Psychology. Vol. Ll0, Issue 2, 1996, ISSN 0735-7036 , pp. 115-124, full text as pdf .
Jill M. Mateo: Developmental and geographic variation in stress hormones in wild Belding's ground squirrels (Spermophilus beldingi). In: Hormones and Behavior. Vol. 50, No. 5, 2006, ISSN 0018-506X , pp. 718-725 full text as pdf .
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 .
Paul W. Sherman: The role of kinship / The course of the year in the Belding Ziesel. In: David MacDonald (ed.): The great encyclopedia of mammals. Könemann in the Tandem-Verlags-GmbH, Königswinter 2004, ISBN 3-8331-1006-6 , p. 610 f. (Translation of the original English edition from 2001).