GEOGRAPHICALLY VARYING HABITAT CHARACTERISTICS OF A WIDE-RANGING AMPHIBIAN, THE COMMON SPADEFOOT TOAD (PELOBATES FUSCUS), IN NORTHERN EUROPE

Anthropogenic habitat loss and degradation are often cited as the primary causes of the recent decline or extinction of many species. The restoration of degraded habitats is therefore vital. Successful habitat restoration, however, requires proper identification of critical habitat characteristics and recognition of the factors that threaten the species. In this study, we describe the geographic variation of habitat characteristics for a widely distributed species with a declining population trend in Europe, the Common Spadefoot Toad (Pelobates fuscus). We examined 407 water bodies and their surrounding habitats in the Netherlands, Denmark, and Estonia by measuring 23 habitat characteristics and evaluating their effects on the species using canonical discriminant, logistic regression, and Spearman correlation analysis. We demonstrate that while the habitat features related to the selection of a breeding site by the species (based on presence/absence of larvae) were generally similar among the countries, habitat characteristics related to the quality of the breeding site (represented by larval abundance) varied considerably. In the Netherlands larval abundance correlated negatively with the area of uncultivated land and positively with the presence of organic crop fields near the breeding site. In Estonia, larval abundance was negatively related to deciduous forests in the surroundings of the reproduction site, and in Denmark it was mainly influenced by aquatic habitat qualities. Such differences could derive from the geographic variation of the habitat requirements of the species, but they could also indicate geographic differences in threatening factors present in each country. In the Netherlands and in Denmark, intensive agriculture seems to be the most important threat to the species, whereas in Estonia the overgrowing of open habitats (e.g., meadows, extensively used fields) and small freshwater bodies have severely affected the species.