Records of blue-coloured European tree frog, Hyla arborea (Linnaeus, 1758)

Abstract

Many colour variations have been observed in Hyla arborea, but blue is considered to be extremely rare, atypical, and even abnormal by certain authors. Two blue-coloured specimens were observed during recent fieldwork in Bosnia and Herzegovina and Slovakia. The possibility that the blue colouration is a result of temperature fluctuations is discussed.