It has been estimated that a third to half of global amphibian species are on the brink of extinction. Therefore, it is crucial that researchers understand the factors that affect the detectability of frog species in order to make amphibian monitoring surveys as efficient as possible. We conducted frog call surveys at six sites on 12 sampling occasions from 20 June – 29 July 2015, in Everglades National Park. Two of these sites were located in pineland, marsh, or mangrove habitats respectively. During each survey, we recorded the species detected, as well as potential environmental covariates (temperature, moon phase, relative humidity, water level, and precipitation in the past 24 hours). We built a single-species occupancy model for each of the seven most common species (Acris gryllus, Anaxyrus quercicus, Anaxyrus terrestris, Eleuthrodactylus planirostris, Hyla cinerea, Hyla squirella, and Lithobates grylio) to estimate the proportion of sites occupied based on habitat type and the environmental factors that affected probability of detection.
Results/Conclusions
The patterns of detectability varied among the seven species. The environmental covariates considered to be the most important were moon phase associated with three frog species, temperature with two species, and relative humidity and water level influencing one species. Habitat type, on the other hand, was only found to be an important predictor of occupancy for the two toad species observed (Anaxyrus quercicus, Anaxyrus terrestris). Thus, based on the variability found among the seven species of frogs, this study highlights the importance of considering a wide range of environmental conditions when monitoring frog populations.