Common frog

Description

The common frog (Rana temporaria), also known as the European common frog, European common brown frog, European grass frog, European Holarctic true frog, European pond frog or European brown frog, is a semi-aquatic amphibian of the family Ranidae, found throughout much of Europe as far north as Scandinavia and as far east as the Urals, except for most of Iberia, Southern Italy, and the southern Balkans. The farthest west it can be found is Ireland. It is also found in Asia, and eastward to Japan. The adult common frog has a body length of 6 to 9 centimetres (2.4 to 3.5 in) its back and flanks varying in colour from olive green to grey-brown, brown, olive brown, grey, yellowish and rufous. However, it can lighten and darken its skin to match its surroundings. Some individuals have more unusual colouration—both black and red individuals have been found in Scotland, and albino frogs have been found with yellow skin and red eyes. During the mating season the male common frog tends to turn greyish-blue. The average mass is 22.7 g (0.80 oz); the female is usually slightly larger than the male. The flanks, limbs and backs are covered with irregular dark blotches and they usually sport a chevron-shaped spot on the back of their neck and a dark spot behind the eye. Unlike other amphibians, common frogs generally lack a mid-dorsal band but, when they have one, it is comparatively faint. In many countries moor frogs have a light dorsal band which easily distinguishes them from common frogs. The underbelly is white or yellow (occasionally more orange in females) and can be speckled with brown or orange. Common frogs are found throughout much of Europe as far north as northern Scandinavia inside the Arctic Circle and as far east as the Urals, except for most of Iberia, Southern Italy, and the southern Balkans. Other areas where the common frog has been introduced include the Isle of Lewis, Shetland, Orkney and the Faroe Islands. It is also found in Asia, and eastward to Japan. The common frog has long been thought to be an entirely introduced species in Ireland, however, genetic analyses suggest that particular populations in the south west of Ireland are indeed indigenous to the country. The authors propose that the Irish frog population is a mixed group that includes native frogs that survived the last glacial period in ice free refugia, natural post-glacial colonisers and recent artificial introductions from Western Europe.