Common Frog

The Common Frog (Rana temporaria) is also known as the European Common Frog or European Common Brown Frog. The Common Frog is found throughout much of Europe as far north as the Arctic Circle. The Common Frog can also be found in Ireland and is the only frog that is found there. However, it is not a native species and was introduced to the country.

Other areas which the Common Frog has been introduced to include the Isle of Lewis, the Shetland Islands and the Orkney Islands, all in Scotland.

Common Frog Characteristics

The adult Common Frog measures around 6 – 9 centimetres long. This species of frog is sometimes confused with the Common Toad, however, the common frog differs from the common toad by its smoother skin compared to the toads more warty skin, and longer hind legs.

The hind legs of the common frog are, however, short compared with other frog species. Another difference between the common frog and the common toad is, the common frog is larger and common frogs hop as opposed to the toads habit of walking. Finally, toads lack dark patches behind the eye often seen on Common Frogs.

The backs and flanks of the common frog vary in color, with olive green, grey-brown, brown, olive-brown, greyand yellow. However, Common Frogs are known to be able to lighten and darken their skin in order to match their surroundings. It is also not unknown for more unusual coloration, both black and red individuals have been found in Scotland. Additionally, albino Common Frogs have been found with yellow skin and red eyes.

Common Frogs flanks, limbs and backs are covered with irregular dark blotches and they usually have a chevron-shaped spot on the back of their neck. Unlike other amphibians, Common Frogs generally lack a mid dorsal band and when they have one, it is quite faint. The frogs underbellies are white or yellow (occasionally more orange in females) and can be speckled with brown or orange.

Common frogs have short hind legs, as aforementioned, and they have webbed feet. Their snout is rounded and their large black/brown eyes are surrounded by gold, flecked with brown. Common frogs have transparent horizontal pupils and they have transparent inner eyelids to protect their eyes while underwater, as well as a ‘mask’ which covers their eyes and eardrums.

Males can be distinguished from females due to hard swellings, called nuptial pads, on their first finger. The nuptial pads are used for gripping females when mating. Males also possess paired vocal sacs, which the females lack.

Frogs cannot swallow, so they ‘push’ their food down by using their large eyes, this means they must close their eyes to swallow.

Common Frog Habitats

Common frogs are largely terrestrial outside the breeding season and can be found in meadows, gardens and woodland. Common frogs hibernate and breed in puddles, ponds, lakes and canals, muddy burrows and can also hibernate in layers of decaying leaves and mud at the bottom of ponds. The fact that they can breathe through their skins allows them to stay underwater for much longer periods of time when they are hibernating.

Common Frog Diet

Adult Common Frogs will feed on any invertebrate of a suitable size. Snails, slugs, worms, beetles, woodlice and flies are all flicked into the frogs wide mouth by its long tongue. The frogs hunt/catch these animals by catching them on their long, sticky tongues. The diets of Common Frogs change significantly throughout their lives, the oldest frogs will feed only on land, younger frogs will also feed in the water. Tadpoles are mostly herbivores, feeding on algae, detritus (bodies of dead organisms) and some plants. They will also eat other animals in small amounts. Common frogs do not feed throughout the breeding season.

Common Frog Behaviour

Common frogs are active almost all of the year, only hibernating when it gets very cold and the water and earth are frozen. In the British Isles, common frogs typically hibernate from late October to January. They will re-emerge as early as February if conditions are suitable and migrate to bodies of water such as garden ponds. Common frogs hibernate in running waters, muddy burrows and can hibernate in layers of decaying leaves and mud at the bottom of ponds. The fact that they can breathe through their skin allows them to stay underwater for much longer periods of time when they are hibernating.

Common Frog Reproduction

Frogs are amphibians and in most parts of the UK, they start spawning in spring. During the mating season, the throat of the male frog turns a bluish color, they are generally light and greyish in color and the female turns browner or sometimes red. The adults congregate in the ponds, where the males compete for females. The courtship ritual involves croaking and a successful male grasps the female under the forelegs. The females, which are generally larger than the males, lay up to 4000 eggs which float in large clusters. The clumps of jelly-like eggs are usually laid around March time. Tadpoles which emerge from the spawn generally take around 12 weeks to develop into tiny froglets. They need water to keep their skin moist so are normally found near water. In the wild, the Common frog has a life span of around 8 years.