Clutch size, egg survival and migration distance in the agile frog (Rana dalmatina) in a floodplain

Abstract

In animals with complex life cycles, the cost of migration among habitats has to be balanced by optimization of growth and survival within each life-stage habitat. In this context, migration distance is expected to depend on local density and movement potential. In ectotherm species, because movement potential is related to body size, larger individuals are expected to cover longer distances than smaller individuals thus avoiding competition. This hypothesis was investigated in the agile frog (Rana dalmatina). For breeding, this species migrates from undergrowth towards ponds located in open environments. Most egg batches were found in sites located 50-100 m from the forest edge. Batches from larger frogs were more numerous at greater distances, as far as 300 m from the forest edge thus confirming the hypothesis: These results must be taken into account for the conservation of this endangered species.