78-7 Sat Jan 2 Landscape structure and movement in the desert grassland whiptail Aspidoscelis uniparens Reynolds, HS*; Sunnarborg, J; University of Kansas; University of Kansas marareyn96@gmail.com
Tradeoffs between finding food and avoiding predators influence where and how animals move through their habitats. In sparsely vegetated arid regions, plant cover and distribution can influence where predators and prey reside. We examine movement of Aspidoscelis uniparens, an asexual, insectivorous lizard that is prey to predatory reptiles and birds in the desert grasslands of SE Arizona. The goal of our study was to elucidate the tradeoff between predator-avoidance and finding food by experimentally testing the effect of vegetation distribution on movement. We established 5 field enclosures with artificial plants placed in uniform, mildly clumped, or highly clumped patterns and then conducted focal observations on marked lizards. We measured time spent moving, time under vegetation, step length, turn angle, and plant revisitation frequency. Turn angle, step length, time spent in vegetation, and time spent moving did not vary with plant distribution, but frequency of plant revisitation, and the tendency for an animal to move to the nearest plant varied significantly with plant distribution. In particular, animals in mildly clumped plots had lower median residence times and were more likely to revisit plants than animals in other treatments. Lizards in uniform plots were more likely to visit the nearest plant than lizards in mildly or highly clumped treatments. Turn angles and step length following a turn were negatively correlated in mildly and highly clumped plots, indicating that A. uniparens might engage in area restricted searching when plants are clumped. Our species of whiptail engage in a structured foraging strategy that improves the efficiency with which they find prey while they minimize predation risks.