Ecology of southeastern Arizona whiptail lizards (Cnemidophorus: Teiidae): population densities, resource partitioning, and niche overlap
Four species of whiptail lizards, two bisexual (Cnemidophorus inornatus and C. tigris) and two unisexual (C. sonorae and C. uniparens), were examined for ecological differences during the 1975 activity season in the desert–grassland of southeastern Arizona.Density estimates indicate the decreasing order of abundance was C. uniparens, C. inornatus, C. tigris, and C. sonorae. Daily activity was generally bimodal. Most active lizards were encountered away from plant cover and utilization of shade patches differed among species, Termites, coleopterans, orthopterans, and various larvae dominated whiptail diets and a wide variety of other prey types were consumed in small quantities. Monthly variations of arthropod biomass and prey diversities between years are presented and discussed.Niche breadths and two measures of niche overlap were calculated and compared for temporal, spatial, and trophic niche components for syntopic species pairs. Ecological differences between bisexual and unisexual species were determined to be minimal.Comparisons of data and niche overlaps indicate the order of importance in separating southeastern Arizona whiptail niches is macrohabitat, microhabitat, time, and food. However, due to higher than average niche overlap and noted similarities among these four species, it is concluded that southeastern Arizona whiptails form a guild of similar lizards.