A Long-term Study of Home Range of Coachella Fringe-Toed Lizards, Uma inornata

Long-term field studies of relatively long-lived lizards can reveal environmental influences and ontogenetic responses over the lifetime of an individual that would not be apparent in data from short-term field studies. Hence, we initiated a long-term (31-yr) study of a population of the Coachella Fringe-Toed Lizard, Uma inornata, to determine demographic (sex, size/age, population density) and environmental (rainfall) influences on HR size of individuals. Mark-and-recapture data and observations on marked individuals provided sufficient sightings to estimate HR size using minimum convex polygons for 45 males and 40 females varying from age 0 (birth year) to age 5. Home range size was positively correlated with age and body size and was nonlinearly correlated with individual growth. Males grew faster and attained larger body size than did females and had larger HRs than did females of similar age. However, the mean body size-adjusted HR size for adult U. inornata did not differ significantly by sex. Home range size was inversely related to density in males but showed no relationship to density in females. There was a significant inverse relationship between HR size and winter rainfall preceding a field season. Within individuals, HRs shifted geographically and increased in size over sequential years as individuals grew. The location of an HR's centroid shifted between 4 and 62 m between years (mean 28 m for males, 15 m for females). Hence, combining HR data from multiple years will overestimate the actual spatial usage of an individual during any single year.