Details
Rana arvalis
The moor frog is a wetland frog spread across Europe and Siberia. It is famous for males that turn bright blue for a short period during the breeding season.
Map: Ecoregions 2017 © RESOLVE (CC BY 4.0) · Natural Earth (PD)
It inhabits bogs, fens, wet meadows, forest ponds and floodplains. Acidic shallow still water and temporary pools are important breeding sites.
Adults are about 5.5-7 cm long. The usual color is reddish to gray-brown with a dark patch behind the eye, while breeding males may become blue over much of the body.
Adults gather to breed in spring, then live mostly alone on damp land. In cold regions, physiological adaptations help them survive freezing conditions.
Adults eat insects, spiders, worms and small arthropods. Tadpoles use algae, organic matter and tiny aquatic organisms.
Spring breeding takes place in shallow ponds. Females lay large egg masses in water, and tadpoles grow quickly as temperatures rise.
The species is globally Least Concern, but some European populations are reduced by drainage, acidification and agricultural change. Blue males mark the brief breeding peak.
