Arizona gray squirrel
| Arizona gray squirrel | ||||||||||||
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Arizona gray squirrel in Madera Canyon in southern Arizona. |
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| Sciurus arizonensis | ||||||||||||
| Coues , 1867 |
The Arizona gray squirrel ( Sciurus arizonensis ) is a species of squirrel from the genus of squirrels ( Sciurus ). It occurs in the southern United States in the state of Arizona to western New Mexico and the north of the Mexican state of Sonora .
features
The Arizona gray squirrel reaches a head-torso length of about 24.0 to 26.0 centimeters, plus a tail that is about the same length. The weight of the animals ranges from about 660 to 740 grams. The back fur of the animals is colored silver-gray, sometimes with an indistinct brown back band. The belly is white to cream-colored, the species also has a conspicuously white to cream-colored eye ring.
distribution
The Arizona gray squirrel occurs in the southern United States in the state of Arizona to western New Mexico and the north of the Mexican state of Sonora. The distribution area consists of three separate ( disjoint ) regions. The northernmost population is from central Arizona to the extreme west of New Mexico south of the Mogollon Rim , others are located in isolated mountain regions in southern Arizona and the mountain ranges in southern Arizona and Sonora that extend into northern Mexico. The height distribution ranges from about 1120 to about 2700 meters.
Way of life
The Arizona gray squirrel lives in the mountain regions and individual mountains of the distribution area in forests from the oak-pine mixed forests of the lower elevations to the coniferous mixed forests of the higher elevations. The animals can also be found in higher populations in the area of rivers with dense vegetation of poplars ( Populus Fremontii ) and plane trees ( Platanus wrightii ). The species is diurnal, and comparatively little information is available about its way of life and ecology. The animals feed mainly on tree seeds and flowers, and more rarely on mushrooms. Due to the very dry habitats, the food composition is very dependent on the amount of rain and the resulting food sources, which can vary greatly over the years. They look for food mainly on the ground and in the branches of the trees. The seeds of the pines, spruces and Douglas firs in the cones reach the animals by removing the individual scales. Also walnuts and acorns are eaten when they are available. Storage facilities are seldom set up as the animals do not overwinter. If they still collect and hoard food, they make shallow beds in the upper layers of the soil or between foliage. The males use very large territories, which include up to 113 hectares , those of the females are significantly smaller with a maximum of 14 hectares and lie within the male, which also overlap.
The nests ( Kobel ) are built in the open branches of the trees or in tree hollows of trees with a large trunk; they mainly consist of small branches, twigs and leaves. The nests can also be used by several individuals. They are used both as a nightly sleeping place and to raise young ones. Reproduction is seasonal and begins with a brief oestrus in the females from February to May, during which the females are mated by several males. The testicles of the males are located in the scrotum below the groin from winter to summer and are withdrawn into a cavity in the groin region. The young are born in late spring to summer, with the litter consisting of two to four young. Studies in 2013 showed that the reproductive time is variable over the years, depending on the available food resources. The stimulus for mating comes from the female; the males are accordingly able to mate over a longer period of time.
The most important predators for the squirrels are birds of prey and predators, mainly foxes and the bobcat ( Lynx rufus ). When there is potential danger, the animals generally behave calmly, but sometimes they also give off barking alarm calls from elevated positions.
Systematics
The Arizona gray squirrel is classified as a separate species within the genus of squirrels ( Sciurus ), which consists of almost 30 species. The first scientific description comes from Elliott Coues from 1867, who described the species on the basis of individuals from the area around historic Fort Whipple north of Prescott in Yavapai County , Arizona.
The subdivision of the species into subspecies differs in various documentation; it has not been conclusively clarified; In the current standard work Squirrels of the World ( Richard W. Thorington Jr. , 2012) no subspecies are distinguished, but the author refers to the inconsistency, since in 2005 in Mammals of the World he described three subspecies that were isolated with the Cover occurrences: The nominate form S. a. arizonensis from the north, S. a. catalinae in the middle part and S. a. huachuca from the south.
Status, threat and protection
The Arizona gray squirrel is not classified in a hazard category by the International Union for Conservation of Nature and Natural Resources (IUCN) due to insufficient data on the stocks of the species and is instead listed as "Data deficient". The species is rare and only found locally, the population sizes are unknown. These also likely change annually depending on the availability of food. Habitat changes due to forest fires in the distribution area are considered to be the greatest threat to the stocks, plus the loss of habitat due to logging and settlement. Like other squirrels, this species is also hunted as a source of meat or for shooting sports, but the economic value of the animals is low.
The introduction of the actually alien Aberthörnchen ( Sciurus aberti ), through which competitive pressure is exerted on the Arizona gray squirrels , probably also has a negative effect on the populations .
supporting documents
- ↑ a b c d e f g h i j 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. 43-44 .
- ^ A b Troy L. Best , Suzanne Riedel: Sciurus arizonensis. Mammalian Species 496, June 23, 1995 ( full text )
- ↑ a b c Sciurus arizonensis in the IUCN Red List of Threatened Species 2015.1. Posted by: AV Linzey, R. Timm, ST Álvarez-Castañeda, I. Castro-Arellano, T. Lacher, 2008. Retrieved September 3, 2015.
- ^ A b Nichole L. Cudworth, John L. Koprowski: Foraging and reproductive behavior of Arizona gray squirrels (Sciurus arizonensis): impacts of climatic variation. Journal of Mammalogy 94 (3), 2013; Pp. 683-690. doi : 10.1644 / 12-MAMM-A-087.1
- ↑ a b c Sciurus arizonensis . 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 .
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. 43-44 .
- Troy L. Best , Suzanne Riedel: Sciurus arizonensis. Mammalian Species 496, June 23, 1995 ( full text )
Web links
- Sciurus arizonensis inthe IUCN Red List of Threatened Species 2015.1. Posted by: AV Linzey, R. Timm, ST Álvarez-Castañeda, I. Castro-Arellano, T. Lacher, 2008. Retrieved September 3, 2015.