Mexican Fox Squirrel

Mexican Fox Squirrel
Conservation status
Least Concern (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Rodentia
Family:	Sciuridae
Genus:	Sciurus
Subgenus:	Sciurus
Species:	S. nayaritensis
Binomial name
Sciurus nayaritensis J.A. Allen, 1890
Subspecies[2]
S. n. nayaritensis S. n. apache S. n. chiricahuae

The Mexican Fox Squirrel (Sciurus nayaritensis) is a species of tree squirrel found throughout the Sierra Madre Occidental as far south as Jalisco, Mexico, northward into the United States only in the Chiricahua Mountains of southeastern Arizona ^[3]. This species, or its subspecies, is sometimes called the Apache, Nayarit, or Chiricahua fox squirrel ^[3].

Description

Physical

Mexican fox squirrels have a grizzled brown back with a yellow to rufous underside, and a charcoal tail frosted with white. Two molts occur each year; the winter pelage is more rufous and the scrotum is often ringed with white^[4]. Mass is approximately 700 grams (25 oz) ^[5].

Behavior

Mexican fox squirrels are diurnal, non-territorial^[6], and do not hibernate during the winter months^[7]. The Mexican fox squirrel forages extensively on the ground and in the forest canopy for tree seeds, flowers, and fungi. Seeds from the cones from pine, Douglas-fir, and true firs are extracted by removing individual cone scales. Acorns and walnuts are also eaten when available, along with a variety of other tree seeds, hypogeous and occasionally epigeous fungi, and insects ^[8]. Mexican fox squirrels occasionally cache large seeds by scatterhoarding them in leaf litter and topsoil ^[4].

The ecology of Mexican fox squirrels has not been studied thoroughly, particularly outside the United States. Densities are often very low ^[9]. Mexican fox squirrels typically produce a single small litter of 1 or 2 young in late spring or summer ^[9]. Mexican fox squirrels nest in ball-shaped dreys composed of sticks and leaves in trees; cavities within large trees are occasionally used, especially by nursing females. They are known to communally nest at times. Large raptors, canids, felids, procyonids and snakes are likely the major predators^[10]. Mexican fox squirrels are notably silent and appear to prefer to seek cover and remain motionless. If startled, they may bark and chuck from safe locations in trees.^[4]

Habitat

Mexican fox squirrels are found in forest ranging from low elevation (~1,500 metres [ 4,900 ft ]) Madrean forests with a mixture of pine and oak to higher elevation mixed conifer forests < 2,700 metres [ 8,900 ft ] ^[11]. Riparian areas with large cottonwoods and sycamores often harbor the highest densities. In the United States, the squirrel lives only in the Chiricahua Mountains of southeastern Arizona ^[12]. The Mexican fox squirrel inhabits forests that were historically maintained by frequent, low-severity fire, and uses areas with open understory and large trees that are typical of such forests ^[13].

Geographic variation

There are three subspecies ^[4].

• S. n. nayaritensis: southern portion of the range. This is a smaller and more yellow subspecies.
• S. n. chiricahuae: Chiricahua Mountains of southeastern Arizona (USA). An endemic form, it is characterized by more reddish throughout.
• S. n. apache: northern and middle portion of the range. This is a form intermediate in size and coloration.

References

1. ^ Linzey, A. V., Koprowski, J. & Roth, L. (2008). Sciurus nayaritensis. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 6 January 2009.
2. ^ Thorington, R.W., Jr.; Hoffmann, R.S. (2005). "Family Sciuridae". In Wilson, D.E.; Reeder, D.M. Mammal Species of the World: a taxonomic and geographic reference (3rd ed.). The Johns Hopkins University Press. pp. 754–818. ISBN 0-8018-8221-4. OCLC 26158608. http://www.bucknell.edu/msw3/browse.asp?s=y&id=12400001. 
3. ^ ^{a b} Best, T.L. (1995) Sciurus nayaritensis. Mammalian Species 492, 1-5.
4. ^ ^{a b c d} Thorington, R.W., Jr., Koprowski, J.L., Steele, M.A., and Whatton, J. (2012) Squirrels of the World. Johns Hopkins University Press, Baltimore, In press.
5. ^ Pasch, B.S., Koprowski, J.L. (2006a) Annual cycles in body mass and reproduction of Chiricahua fox squirrels (Sciurus nayaritensis chiricahuae). Southwest. Nat. 51, 531-535.
6. ^ Pasch, B.S., Koprowski, J.L. (2006b) Sex differences in space use of Chiricahua fox squirrels. J. Mammal. 87, 380-386.
7. ^ Koprowski, J.L., Corse, M.C. (2005) Time budgets, activity periods, and behavior of Mexican fox squirrels. J. Mammal. 86, 947-952.
8. ^ Koprowski, J.L., Corse, M.C. (2001) Food habits of the Chiricahua fox squirrel (Sciurus nayaritensis chiricahuae). Southwest. Nat. 46, 62-65.
9. ^ ^{a b} Pasch, B.S., Koprowski, J.L. (2005) Correlates of vulnerability in Chiricahua fox squirrels, in: Gottfried, G.J., Gebow, B.S., Eskew, L.G., Edminster, C.B. (Eds.), Proceedings: Connecting mountain islands and desert seas: biodiversity and management of the Madrean archipelago II. USDA Forest Service, Gen. Tech. Rep. RMRS-P-36, Rocky Mountain Research Station, Fort Collins, CO, pp. 426-428.
10. ^ Kneeland, M.C., Koprowski, J.L., and Corse, M.C. (1995) Potential predators of chiricahua fox squirrels (Sciurus nayaritensis chiricahuae). Southwest. Nat. 40, 340-342.
11. ^ Hoffmeister, D.F. (1986) Mammals of Arizona. The University of Arizona Press, pp. 212-213.
12. ^ Brown, D.E.(1984) Arizona's tree squirrels. Arizona Game and Fish Department, pp. 39-61.
13. ^ Doumas, S.L. (2010) Return of historical fire as a conservation tool: burn severity impacts Mexican fox squirrels. MS thesis, University of Arizona.

External links

• Smithsonian National Museum of Natural History, North American Mammals, Sciurus nayaritensis[1]