Mexican fox squirrel
|Mexican fox squirrel|
J.A. Allen, 1890
|Mexican fox squirrel's range|
The Mexican fox squirrel (Sciurus nayaritensis) is a species of tree squirrel found throughout the Sierra Madre Occidental of Mexico as far south as Jalisco — and northward into the Chiricahua Mountains of southeastern Arizona, U.S.
The Mexican fox squirrel has 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. Mass is approximately 700 grams (25 oz).
- Food sources
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. Mexican fox squirrels occasionally cache large seeds by scatterhoarding them in leaf litter and topsoil.
The ecology of the Mexican fox squirrel has not been studied thoroughly, particularly outside the United States. Densities are often very low. Large raptors, canids, felids, procyonids and snakes are likely the major predators.
Mexican fox squirrels typically produce a single small litter of 1 or 2 young in late spring or summer. 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. 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.
Mexican fox squirrels are found in forests 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 ]. 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.
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.
There are three subspecies.
- Sciurus nayaritensis nayaritensis (Nayarit fox squirrel): southern portion of the distribution range. This is a smaller and more yellowish subspecies.
- Sciurus nayaritensis apache (Apache fox squirrel): northern and central portion of the distribution range. This is a subspecies intermediate in size and coloration.
- Sciurus nayaritensis chiricahuae (Chiricahua fox squirrel): an endemic subspecies of the Chiricahua Mountains of southeastern Arizona (US). Characterized as more reddish throughout.
- Linzey, A. V.; Koprowski, J. & Roth, L. (2008). "Sciurus nayaritensis". IUCN Red List of Threatened Species. Version 2008. International Union for Conservation of Nature. Retrieved 6 January 2009.
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- Thorington, R.W., Jr., Koprowski, J.L., Steele, M.A., and Whatton, J. (2012) Squirrels of the World. Johns Hopkins University Press, Baltimore, 472 pp.
- 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.
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- Koprowski, J.L., Corse, M.C. (2001) Food habits of the Chiricahua fox squirrel (Sciurus nayaritensis chiricahuae). Southwest. Nat. 46, 62-65.
- 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.
- 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.
- Hoffmeister, D.F. (1986) Mammals of Arizona. The University of Arizona Press, pp. 212-213.
- Brown, D.E.(1984) Arizona's tree squirrels. Arizona Game and Fish Department, pp. 39-61.
- Doumas, S.L., Koprowski, J.L. (2012) Return of fire as a restoration tool: long-term effects of burn severity on habitat use by Mexican fox squirrels. Restoration Ecology, doi: 10.1111/j.1526-100X.2012.00864.x
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