Pool Frog
Identification: Length up to 8 cm, usually 4.5-6.5 cm. Females larger than males. Snout quite sharp. Back mostly grass green, often spotted with brown or dark brown. Sometimes also uniform brown, but the side of the head usually is still green. On the flanks, the spots are often fused into irregular bands. Usually a light green stripe over the middle of the back. Groin area often distinct yellow to orange. Back of thighs yellow or orange with dark brown marbling. Belly white, sometimes with grey spots. On the border between the flank and back, there are dorsolateral folds, which alternate just in front of the hind legs. Large, hard, sharp-edged, semicircular metatarsal tubercles (up to half the length of the toe on which the metatarsal tubercle is standing). Well-developed webbing on the relatively short hind legs. In the breeding season, males are uniformly yellowish with a golden yellow iris and grey nuptial pads on the thumbs. Males have thicker front legs than females and the spots on their body are lighter coloured. They have two white vocal sacs behind both corners of the mouth.
Range: Mid and northeast Europe, east as far as Russia. In the British Isles it may have been native to East Anglia, but now is probably extinct. Existing populations are probably all introductions.
Habitat: Prefers permanent, slightly acid, sun-exposed waters, poor in nutrients on sandy soil in open landscapes, like meres on heaths and waters on moorland. The water edges need to be well overgrown. Also in larger ponds in woods and waters on river clay. In the south of its range, also found in larger, more nutritious waters. In the Alps, they occur up to altitudes of 1500 metres.
Habits: Active from March to October. Mainly diurnal, but can be active at night, especially in the breeding season. Basks extensively during the day. Stays mostly in the water, but goes on land to forage, mainly at night. Young animals leave the water more often and go further than mature animals. In the breeding season (from the end of April to the beginning of July), the males often call in dense associations. In a season, 400-3500 eggs are laid, divided between multiple clumps. Depending on the temperature, the larvae hatch after 1-2 weeks, when they are 5-8 mm long. They grow to a length of 5-7 cm and then metamorphose after 2-4 months. The newly metamorphosed frogs are 2-2.5 cm long and mature after 2-3 years. Pool Frogs are less restricted to water than the other green frogs. After the breeding season, they spend most of their time on land; only in dry conditions do they go back to the water. From the end of August, they migrate to their hibernation quarters. They feed mainly on insects, spiders, slugs and earthworms. Their most serious enemies are mammals like the marten and fox, birds like herons and storks, and Grass snakes and predating fish. Hibernates mostly on land.
How to find: The best chance is in the breeding season (May to July). The males gather together and form large and dense associations. Calls mainly in the evening, but on warm, sunny days also during the day.
Call: Humming, rattling, grunting "rè - rè - rè" and "auwck...auwck...auwck...", increasing in tone. In quick succession (short pulses up to 1.5 seconds long). The pulses occur faster than in the Edible Frog.