Common frog

Rana temporaria is a short, stout amphibian without a tail in its adult stage, with a broad, flattened head. Its hind legs are strong and are used for both jumping and swimming. Its coloration usually includes shades of brown, but it may also be grey, olive, yellowish or pinkish. A dark brownish-black triangular patch is present around the tympanum. There are differences between the sexes: females are usually more yellowish and may have reddish spots on their flanks; during the breeding season, males may develop bluish areas on the back and throat.

It occupies a variety of damp environments throughout its range and is common in cool forests at higher elevations and in wet meadows. It is also found in mountain lakes, ponds, lakes and watercourses. Although it can move away from water, it usually hides in damp places during the day and seeks food at night or on rainy days. In winter, it remains in shelters in the ground. Its diet varies with age: tadpoles eat algae and, as they grow, also plant matter and sometimes small insects; juveniles and adults eat invertebrates, including insects, larvae, woodlice, spiders, snails and earthworms.

Breeding takes place in water and fertilization is external. During mating, the male clasps the female as she lays eggs in gelatinous coverings, grouped in masses; the adults do not care for the eggs afterwards. Aquatic tadpoles with gills hatch from the eggs. During metamorphosis, the hind legs appear first, followed by the front legs; the gills disappear, lungs develop and the tail is absorbed. The juveniles leave the water and begin a semi-aquatic life. The breeding season varies by location: in the warmer lowlands it is reported from February to March, and it may extend until June in the north and at higher elevations. Sexual maturity is reached at about three years of age, and individuals may return to the water where they underwent metamorphosis to breed.