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RELATIONSHIPS OF BIRDS, LIZARDS, AND NOCTURNAL RODENTS TO THEIR HABITAT IN TUCSON, ARIZONA Developed land parcels become less similar to native habitat, due to the increasing presence of structures (e.g., houses, outbuildings, apartment complexes), paved areas, altered vegetation, and direct human and pet-related disturbances to native wildlife. As a result, developed areas become less able to support populations of many native wildlife species (Gavareski 1976, Green 1984, Sears and Anderson 1991). In this study, I examined the relationship between wildlife and factors describing residential urbanization in Tucson, Arizona. I included 3 groups of animals in this study: birds, lizards, and nocturnal rodents. Other researchers have identified factors which influence the distributions of each of these groups across urban gradients. Birds. In Tucson, descriptive comparisons have been made for birds between undeveloped and developed land parcels which were otherwise similar. Emlen (1974) compared community composition between a residential area and an undeveloped desert area and emphasized the avian resources present at each site. Tweit and Tweit (1986) used data from existing Tucson area studies to summarize avian community composition in various habitat types. They also summarized important habitat types for individual birds. Mills et al. (1989) documented relationships between the volume of native and exotic vegetation and breeding bird abundance, density, and diversity. Stenberg (1988) compared land cover composition to the number of species present and identified elements of the metropolitan environment that were important in predicting bird species richness. Research needed to be conducted in Tucson that identified ecologically important habitat factors throughout the urban residential spectrum. In addition, predictive models that incorporated habitat variables and objective community response variables needed to be generated. The relationship among community parameters such as abundance, richness, and evenness had to be identified to determine how wildlife community regulatory mechanisms are affected by residential factors. Further, while habitat associations have been reported for many bird species, no effort had been made to identify thresholds beyond which individual species declined. Lizards. Little information exists on the distributions of lizards in urban areas in the Southwest. Morrison et al. (1994) documented the loss of 3 lizard and 11 snake species from an urban park in San Diego, CA. They implicated physiognomic and floristic changes in the habitat, high levels of human disturbance, and the presence of feral predators. Additionally, herpetofauna populations have been impacted by factors such as destruction of protective ground cover (Minton 1968, Orser and Shure 1972), the presence of roads (Gibbs et al. 1971) and window wells (Heck 1971), increased predation rates (Schaaf and Garton 1970), collecting (Beebe 1973), and pollution and pesticides (Anderson 1965, Scott 1973). To date, no study in the Southwest has quantified factors associating residential urbanization with lizard assemblages and populations. Nocturnal Rodents. Comparing an urban park and an undisturbed control, Morrison. et al. (1994) determined that the small mammal assemblage in the park was impoverished and dominated by the exotic house mouse. They reported the disappearance of 9 insectivore and rodent species from the park area, and cited competition from house mice (Mus musculus) and habitat degradation as potential causal factors. Stenberg (1988) surveyed sign (scat, tracks, den holes) in Tucson, and reported that small mammals seemed to follow a concentric pattern of distribution around the metropolitan center, with overall diversity declining as urbanization increased. Duncan (1990) conducted a preliminary study on the effects of visitor use on vegetation and nocturnal rodent populations in Saguaro National Park, Tucson. Although he found vegetative differences between experimental and control sites, he could not attribute them to human use, and he found few differences in rodent densities. Other factors found to affect rodent distributions in urban areas include habitat patch isolation (Goszczynski 1979a), dogs and cats (Goszczynski 1979b), vegetation alterations (Dickman and Doncaster 1987, 1989), and roads (Oxley et al. 1974). No information exists in the Southwest on the effects of quantifiable factors associated with residential urbanization on nocturnal rodent assemblages and populations. Study Objectives My primary goal was to develop habitat models which would accurately predict the distribution of birds and lizards throughout the urban residential gradient in Tucson, Arizona. Because land use planners and developers affect habitat changes in the form of large scale ground cover changes, I tested hypotheses concerning 2 ARIZONA GAME fr FISH DEPARTMENT, TECH. REP. 20 STEPHEN S. GERMAINE 1995