In plots where cattle (Bos taurus) grazing was excluded, small mammals were 50% more abundant than in areas where grazing was present. All species caught were found on both the grazed and ungrazed sites, therefore the relative abundance of individual small mammal species was variable. The species most commonly found in arid grasslands or habitat with considerable ground cover, such as cotton rats (Sigmodon hispidus), western harvest mice (Reithrodontomys megalotis), and Taylor's pygmy mice (Baiomys taylori), had a greater mean abundance in livestock exclosures. Species more commonly found in open habitats similar to the studies' surrounding desert scrub, such as heteromyid rodents, had a greater mean abundance in the grazed plots. Other species did not demonstrate any difference in abundance on grazed versus ungrazed plots. Their ability to use brush piles, which are not affected by grazing, may be the reason for this.
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