Desert Shrew (Notiosorex crawfordi)
Main sources: Nowak, Ronald, 1991, Walker's Mammals of the world, Fifth Edition (two vols.), Baltimore: Johns Hopkins University Press; Hoffmeister, D. F., 1986, Mammals of Arizona, Tucson: University of Arizona Press; Burt, W. & R. Grossenheider, eds., 1976, A Field Guide to the Mammals, Peterson Field Guides: Houghton Mifflin; Eisenberg, John, 1980, The Mammalian Radiations, Chicago: University of Chicago Press; Merlin, Pinau & Peter Siminski, "Shrews", in Steven Phillips and Patricia Comus, eds., 2000, A Natural History of the Sonoran Desert, pp. 492, Arizona-Sonora Desert Museum Press, Tucson
Our Desert Shrew -- the sole known species member of this Genus -- has a short tail, conspicuous earpoints, and various skull features that distinguish it from other shrews found in Arizona. Its range extends throughout the southwestern U.S. and northern Mexico (though they are rarely seen). Desert Shrews live wherever cover is ample -- under dead Agave plants, in woodrat dens, etc. (wherever the refuge will exclude most predators, since they sleep very deeply), where they build fluffy nests of shredded vegetable material (the innermost part of the nest is of a slightly finer material). Small, indistinct runways may radiate out from these nests.
Because their active metabolic rate is high, Desert Shrews must lower it when food is scarce, and they enter reduced metabolic torpor when this happens (Hoffmeister, p. 52). They eat a variety of arthropods, lizards, and small mice, and their kidney structures enable them to survive without supplementary water -- living from the moisture obtained from their prey. They eat scorpions, appearing to be immune to the scorpion's sting. (Merlin & Siminski, cited above) Their main predators may be owls and snakes.
These shrews apparently bear young throughout the year, probably two litters per year, around six per litter, born helpless, hairless, and blind, but the offspring mature rapidly and approach adults in size by the 40th day. Individuals appear to live more than one year.