Effects of habitat characteristics in an anthropized landscape on the spatial behavior and abundance of a common chameleon (Chamaeleo chamaeleon) population

Abstract

Currently, roads are conspicuous components of most landscapes around the world, with mid-21st century forecasts predicting that the number of both roads and vehicles will increase. Roads are considered one of the main drivers of biodiversity loss. We show the effects of a highway on the spatial behavior and the abundance of a common chameleon population. We used the Favorability Function (FF) to assess how the observations (i.e., presence/absence) of common chameleons were affected by distance from the highway, habitat characteristics, and food availability. In addition, we assess if the relative abundance of common chameleons were affected by distance from the highway. We obtained a significant favorability model with two variables (shrub and the distance to the highway). Higher proportions of ground covered by shrub were associated with lower favorability for the presence of common chameleon, while greater distances from the highway were significantly related to more favorable areas for the species. The relative abundance of common chameleons was significantly higher in the bands furthest from the highway. Both results constitute the first evidence regarding the common chameleon and the indirect impact of highways on adjacent habitat. This road-avoidance behavior may be the result of an ecological effect known as the road-effect zone (REZ). Due to the linear nature of roads and their length, even small avoidance zones can imply the loss of large tracts of habitat, highlighting a landscape-scale impact and possible population level impacts. This is of particular significance in peninsular Spain where the distribution of the common chameleon is mostly restricted to highly anthropized coastal areas with a high road density.