Abstract

This study investigated the influence of seasonality on diet and foraging behavior of the whiptail lizard Ameivula (Cnemidophorus) ocellifera in the Caatinga of northeastern Brazil. Diet composition was identified through stomach analysis of lizards collected monthly by active search during 2009 (rainy and dry seasons) and half of 2010 (rainy season). Foraging behavior was investigated during one rainy and one dry month of 2012, allowing us to determine the percent of time spent moving (PTM), number of movements per minute (MPM), and number of successful attacks on prey by lizards during foraging activity. Analysis of stomach contents showed significant seasonal differences in diet: insect larvae, Coleoptera, and Orthoptera predominated during the two rainy seasons (2009 and 2010); insect larvae, Hemiptera, Araneae, and Orthoptera predominated in the dry season. Prey movement index was lower during rainy seasons, mainly because of more insect larvae consumed during those periods. Population niche breadth was broader in the dry season, but individual niches did not differ significantly between seasons. When foraging, the average PTM was 61.1 ± 15.1%; MPM was 2.03 ± 0.30; and prey items captured/min was 0.14 ± 0.14. PTM for A. ocellifera was similar to values found for North American whiptails (Aspidoscelis), but MPM was relatively higher. Seasonal differences were observed in PTM, which were significantly higher in the rainy season. This difference may represent a behavioral adjustment in response to differences in seasonal food availability.