The effects of seasonality on the foraging behavior of Tropidurus hispidus and Tropidurus semitaeniatus (Squamata: Tropiduridae) living in sympatry in the Caatinga of northeastern Brazil

Abstract

In this study, we performed field observations of 38 and 84 specimens of the lizards Tropidurus hispidus (Spix, 1825) and Tropidurus semitaeniatus (Spix, 1825), respectively, inhabiting a Caatinga in the state of Rio Grande do Norte, northeastern Brazil, in order to describe the foraging behavior, measure the foraging intensity (number of movements, time spent stationary, distance traveled and number of attacks on preys) and investigate the effects of seasonality on the foraging strategies of these two species of lizards. During the dry season, both species showed no significant differences in foraging intensity. In the wet season, on the other hand, only the distance traveled was similar for both species. Tropidurus semitaeniatus displayed a larger mean number of movements (9.8 ± 1.2) and attacks on preys (1.7 ± 0.3) when compared to T. hispidus (3.0 ± 0.8 moves; 0.3 ± 0.1 attacks). Additionally, mean time spent stationary was significantly longer for T. hispidus (596.6 ± 1.0 seconds) than for T. semitaeniatus (587 ± 2.1 seconds). Results suggest that the low number of movements and short distance traveled (maximum of 1000 cm during 10-minute intervals) are consistent with the categorization of T. hispidus and T. semitaeniatus as sit-and-wait foragers. Given our results, we conclude that both species co-exist under limiting conditions during the dry season, with similar foraging behavior and similar rates of foraging intensity, segregating with respect to these variables in the wet season.