The Herpetological Journal

pp. 163-171
Authors: van Buggenum, Harry J.M. & Vergoossen, Willem G.

Abstract: We investigated the importance of habitat measures and climate variables on the development of a managed European tree frog (Hyla arborea) population based on chorus counts between 1978 and 2011, using Akaike's Information Criterion (AICc) to select the best predictors. Pond area increased over the study period through site management, and was the most important variable in all models. In the density independent models, the annual numbers of calling males were positively correlated with total area of ponds two years before the count, a time lag which corresponds with the time needed for metamorphs to mature. Mean daily temperature, the total amount of precipitation during the breeding season (both with a 2 year time lag) and high winter temperature before the breeding season also had positive effects on the H. arborea population. A linear regression of temperature with study years revealed an annual increase of 0.08 °C, whereas precipitation showed no trend. Yearly population growth rates were furthermore density-dependent, and influenced by temperature during breeding season. Our study showed that a combination of habitat management practices and increasing temperatures likely through global warming positively affected the H. arborea population.

Keywords: DENSITY DEPENDENCE, LONG TERM MONITORING, AMPHIBIAN, AICC, MODEL SELECTION, PREDICTORS