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.

The mating season for pool frogs begins significantly later in the year than it does for common frogs. In the months of May and June, as the evenings become warmer, mating season begins. The spawning "rafts" are normally much smaller than those of the common frog, and the tops and bottoms of the individual eggs have a yellowish-brown coloration.  Even on the warmest days, it is common for pool frogs and other members of the green frog "complex" to bask in the sunlight