Effects of residential density on sonoran desert nocturnal rodents

We compared nocturnal rodent distributions among residential developments and in adjacent undeveloped native habitat remnants in Tucson, Arizona during October 1994. We trapped rodents in 2 low density (0.5 houses/ha) developments, 2 medium density (7.5 houses/ha) developments, and in 4 adjacent blocks of undeveloped native habitat using trap lines of 50 snap traps spaced at 2 traps every 10 meters. We compared species abundance, species richness, and total abundance among the 4 site types in a contingency table using a 2-tailed Fisher's exact test, and used post-hoc tests where the null hypothesis of no difference among sites was rejected. We encountered 144 individuals representing 5 species of nocturnal rodents in 1200 trap nights. Of 4 native rodent species, none were captured in medium housing density sites. House mice (Mus musculus) were captured only in medium housing density sites. Total rodent abundance was lower in both the medium density residential and the adjacent undeveloped sites than in either low density or adjacent undeveloped sites. Low density housing must be included in the developing matrix if the full complement of native nocturnal rodents is to be retained in Tucson.