Distribution of Merriam's Shrew (Sorex merriami) and the Dwarf Shrew (Sorex nanus), and New Records for New Mexico

Abstract

America, although this fact is obscured in broad-scale distribution maps (e.g., Hall, 1981) that artificially encircle highly isolated populations. For example, distribution of the S. monticolus complex (S. monticolus and S. neomexicanus; Alexander, 1996) in New Mexico and Arizona (Findley et al., 1975; Hoffmeister, 1986; Fig. la) closely matches the disjunct distribution of ponderosa pine (Pinus ponderosa) forest and higher elevation plant communities in the region (Kiichler, 1970). In fact, each of the 7 species of Sorex known from New Mexico (S. cinereus, S. merriami, S. monticolus, S. nanus, S. neomexicanus, S. palustris, and S. preblei) exhibit similarly fragmented distributions, with disjunct populations restricted to relatively mesic sites, usually of higher elevation (Findley et al., 1975; Kirkland and Findley, 1996). An ample fossil record (Harris, 1985, 1989; Harris and Carraway, 1993) documents a broader distribution of Sorex in the Southwest during the Wisconsinan full-glacial, and currently disjunct populations are evidently relicts of that more continuous distribution. Herein we report new localities for the dwarf shrew (S. nanus; Fig. ib) and Merriam's shrew (S. merriami; Fig. ic) in New Mexico and summarize the southern-