Northern pool frogs
The coloration of pool frogs is quite diverse, but the species that has been successfully restored to the United Kingdom is mostly brown with dark brown or black blotches distributed over the back and a lighter, often yellow dorsal stripe.
The size of a pool frog is comparable to that of a common frog, measuring up to 6 centimeters in length on average, with females being somewhat bigger than males. The males have a loud call that is created by a pair of inflated pouches (vocal sacs) either side of the mouth during the breeding season. This is a trait that is lacking in the common frog Rana temporaries.