Spatiotemporal dynamics in the roosting ecology of the green toad: Implications for urban planning and nature conservation

Continuously growing urbanisation and the ongoing rebuilding of urban habitats affect amphibians, the most threatened vertebrate group. Even though the effects of urbanisation are mostly negative, some artificial components of the urban landscape may also display positive relationships with amphibian populations and therefore work in favour of their persistence in cities. Roosts provide protection from predation, desiccation and offer invertebrate prey availability; therefore, roost availability is an essential necessity of amphibian maintenance in urban areas. On the example of the European green toad Bufotes viridis, a typical urban dweller, we investigated roost-type occupancy and its distribution relative to a breeding pond during the active season (from June to October). The analysis was done with regard to the different life stages of individuals from three urban populations. Green toads used fissures situated in various man-made constructions (e.g., buildings, roads, pathways) for roosting cavities, however without any predominant pattern among toad life stages. The local architecture of the study sites mainly determined the type of occupied roosts. In adults and juveniles we recorded a gradually increased roost distance from breeding pond, while subadults were found roosting further from the water during the active season. Management measures aimed at maintaining a favourable state of green toad populations in urban environments should incorporate a complex of actions that consider general as well as the local ecological patterns of particular populations.