Meeting Abstract

P2.10  Jan. 5  Variation in food acquisition behavior of an ambush predator: patterns and correlates ANDERSON, R. A.*; ROSE, E.; Western Washington University; Western Washington University Roger.Anderson@wwu.edu

Documenting intraspecific variation in food acquisition behavior and investigating consequences of that variation among individuals is imperative before performing an integrative, micro-evolutionary field study of food acquisition. A tractable study species for this work is the leopard lizard Gambelia wislizenii. Leopard lizards eat lizards and large insects, but in the north end of their geographic range (e.g., Oregon), G. wislizenii are mostly insectivorous. Female leopard lizards are the larger sex; preliminary evidence pointed to females being relatively long-wait ambushers compared to males, perhaps because females sought more lizard prey. A focal observational study of G.wislizenii was performed mid-summer, when lizards were post-reproductive, and their primary activity was food acquisition, albeit limited by thermoregulation. Microhabitat temperatures were documented, and prey availabilities were measured. Focal observation variables included: MPM (number of movements per minute), PTM (percent time spent moving), habitat use, and types of prey pursued. Both G. wislizenii and its prey were more active in mid-morning hours when conditions were thermally salubrious. Stops made by G. wislizenii were apparent visual searches for movements of prey, whereas moves by G. wislizenii were apparent changes in search position. Gambelia wislizenii can be characterized as brief-wait ambush predators, although variation in stop times were considerable. The low PTM values of G. wislizenii were characteristic of ambushers, but the high MPM values of G. wislizenii were similar to those of intensive foragers. Food acquisition patterns differed slightly between sexes, but lizard body size and the mesohabitat the lizard is in when the focal observation occurs also affect food acquisition.