Local habitat measures derived from aerial pictures are not strong predictors of amphibian occurrence or abundance

Abstract

Species monitoring plays an important role in determining whether conservation targets are being met. However, monitoring programs can be costly and logistically demanding. When site characteristics are strongly linked to species’ status, managers may instead choose to monitor the site characteristics themselves as a surrogate of species status. In this study, we modelled the occupancy status and abundance of pond-breeding amphibians in a network of protected areas across Switzerland. We incorporated remotely-sensed data describing habitat within breeding sites in order to identify any characteristics which could act as monitoring surrogates for amphibian species’ status. We found that connectivity between amphibian breeding sites was an important predictor of occupancy patterns for all species, but that abundance patterns were poorly predicted. Despite expectations that the habitat characteristics assessed from aerial images were important for the species studied, we found that these variables were rarely strong predictors of occupancy patterns. These results highlight the importance of caution in identifying species monitoring surrogates, and the need to explicitly demonstrate strong relationships between surrogates and state variables of interest before surrogates are used.