Abundance and habitat use of the lizard Sceloporus utiformis (Squamata: Phrynosomatidae) during the seasonal transition in a tropical environment

Resumen

Several behavioral and ecological studies have focused on the comparison of different variables among seasons. However, little is known abou tthe transitional period between the end of the rainy season and the start of the dry season. To address this transition, we measured the abundance and habitat use of the lizard Sceloporus utiformis from the end of the rainy season to the beginning of the dry season. Two study sites were employed, both located in western Mexico: Chamela Biological Station and Manantlán Biosphere Reserve. These sites vary in elevation and distance from the coast. We compared the 2 environments with respect to ambient temperature, relative humidity and canopy cover in both the drier areas in the surrounding tropical dry forest and in wetter environment in vegetation along banks. Our results indicated that the abundance and habitat use of S. utiformis change gradually with seasonal transition, less abrupt changes in vegetation, followed by the high elevation forest and finally the low elevation forest. The population abundance of S. utiformis increased during the seasonal transition, and the age structure changed from adult-dominated to juvenile-dominated. During the wet-to-dry transition, the use of herbaceous microhabitat was reduced and the use of leaflitter and trees increased at all sites.