Pool Frog (Pelophylax lessonae)
Pool Frogs were presumed extinct in the wild in 1995 but their native status was actually debated for many years as similar ‘exotic’ species had been introduced from Europe. Research was carried out in the 1990s which showed pool frogs have regional ‘accents’ to their calls and further genetic studies revealed their true ancestry. It was determined that English Pool Frogs belonged to a distinct, and very rare, northern group of Pool Frogs, also found in Sweden and Norway. Pool Frogs have since been reintroduced at a single site in Norfolk. They belong to a complex of species known as ‘Green Frogs’ which also includes Marsh frogs and Edible Frogs.
| Identification | Adult females up to 9 cm in length. Males significantly smaller. Brown or green with dark blotches across the back and a cream or yellow dorsal stripe. Pair of ridges run from the eyes down the back. Vocal sacs visible either side of the mouth of breeding males. Oval, horizontal pupil.
Call: a loud call, often likened to ducks quacking or rapid laughter ‘re…re…re’. |
| Distribution | Native to the UK. Very rare in the UK. Previously thought to be extinct here but recently reintroduced to a site in East Anglia. Genetic analysis and studies of male calls revealed that English pool frogs belonged to a distinct, and very rare, northern group of Pool Frogs, also found in Sweden and Norway. |
| Ecology | Found in damp densely vegetated areas. Prefer slow flowing waterways such as calm rivers, ponds or marshes. Hibernates on land during the winter. Feed on a wide range of invertebrates including spiders, insects, moths and flies. Small spawn ‘rafts’. Individual eggs are brown on top and yellowish underneath. |
| Predators and other threats | Threatened by drainage of fenlands. Predators include Grass Snakes, herons, owls and some wading birds. |
A year in the life…Spring
Adult frogs emerge from their overwintering sites in late spring and head to a pond to breed. Males have a loud call generated by a pair of vocal sacs either side of the head.
Summer
Pool Frogs lay clumps of spawn (eggs) in the pond during late spring/early summer; breeding coincides with the onset of warm nights in May/June. These clumps are typically smaller than those laid by the common frog; individual eggs are brown above and yellowish below. Pool Frogs are very aquatic and spend much of the year in or near the water; they also tend to bask in sunshine even on very hot days.
Autumn
Adults and froglets prepare for winter by feeding up on invertebrates.
Winter
Pool Frogs normally hibernate on land between October and April.
N.B. Pool Frogs have full legal protection under UK law making it an offence to kill, injure, capture, disturb or sell them, or to damage or destroy their habitats. This applies to all life-stages.