Microhabitat utilization and population density of the lizard Gonatodes humeralis (Guichenot, 1855) (Reptilia: Squamata: Gekkonidae) in forest areas in Manaus, Amazonas, Brasil

Gonatodes humeralis is a small lizard widely distributed in Amazonia and found on tree trunks. An increase in its abundance in deforested areas has been observed in several studies, although the factors causing this increase remain unknown. In this study, population density was estimated in forests in different stages of regeneration. Population densities and habitat characteristics were analyzed by multiple regression. This analysis showed that population density was positively related to the number of available trunks and negatively related to forest regeneration stage. Analysis of microhabitats used by G. humeralis was made to evaluate whether the species selects the tree trunks it uses. This selection has been reported for arboreal lizards, although only diameter was quantified. Comparison between the frequency distributions of used and available trunks showed that G. humeralis did not select trunks either by circumference or by canopy density. However, amount of leaf litter and trunk rugosity were used in different proportions relative to the available, suggesting that this species prefers trunks with intermediate rugosity and less leaf litter around it. This selection may be related to ease of movement between trees, while the selection of trunks with intermediate surface rugosity may be related both to lizard mobility and predator avoidance. Additional studies would show whether these patterns are also found in other populations