Common Frog

The common frog (Rana temporaria) is a small, plump amphibian with a rounded snout, webbed feet, and long hind legs built for both swimming and hopping. Adults typically measure 6 to 9 centimetres in length and weigh around 22.7 grams, with females usually a little larger than males.

Their colouring varies widely - olive green, grey-brown, brown, yellowish or rufous - and they can lighten or darken their skin to match their surroundings. The flanks and back are marked with irregular dark blotches, and there is usually a dark spot behind each eye. The underbelly is white or yellow, sometimes speckled with brown or orange. Unusually coloured individuals do occur: black and red common frogs have been recorded in Scotland, and albino individuals with yellow skin and red eyes have also been found.

Common frogs are semi-aquatic, spending much of their time in damp places on land but returning to ponds and other still fresh water to breed. They are a familiar sight in UK gardens and are widely found in both urban and rural environments.

The common frog has a fossil record stretching back to at least the Early Pleistocene, with remains found at a site in Hungary dating to around the time of the Mid-Pleistocene Transition.

Today common frogs are found throughout much of Europe, from Ireland in the west to the Urals in the east, and as far north as Scandinavia inside the Arctic Circle - further north than any other amphibian in the region. They also range into Asia as far east as Japan. They are absent from most of the Iberian Peninsula, southern Italy, and the southern Balkans.

In Ireland, common frogs were long thought to be entirely introduced, but genetic analyses suggest that some populations in the south-west of the country are native, and researchers propose that these survived the last glacial period in ice-free refugia. Researchers propose that the Irish population is a mixture of these natives, natural post-glacial colonisers, and recent introductions from Western Europe. Common frogs have also been introduced to islands including the Isle of Lewis, Shetland, Orkney, and the Faroe Islands.

Common frogs are solitary outside the breeding season, living quietly in damp spots near ponds, marshes, or long grass. They are active for much of the year, hibernating only in the coldest months - typically from late October to January in the British Isles, re-emerging as early as February if the weather allows.

During hibernation they shelter in running water, muddy burrows, or under layers of decaying leaves and mud at the bottom of ponds. The oxygen they absorb through their skin is enough to sustain them while they are cold and motionless during hibernation. In very cold northern parts of their range they may remain under ice for up to nine months, yet can still be relatively active at near-freezing temperatures.

Common frogs are opportunistic, patient hunters. During the day they tend to hide in damp places, becoming more active at night when they search for food. Their diet shifts with the seasons: in summer it leans heavily on crane flies and moth and butterfly larvae, while woodlice, beetles, slugs, snails, and earthworms also feature regularly. Tadpoles feed mainly on algae and decaying plant matter, becoming carnivorous as their hind legs develop.

Each spring, common frogs migrate to ponds to breed. Males arrive first and wait for females, competing with one another, with larger males mostly occupying the shallower areas of the pond that are better suited to egg-laying. They do not hold territories in the usual sense and rarely fight directly. Females lay between a few hundred and 5,000 eggs in clumps, which gather together in large masses that help keep the developing embryos warm.

Common frogs typically live between six and eight years in the wild.

One of the most serious diseases affecting common frogs is ranavirus, which causes skin ulcerations and haemorrhaging. Mortality rates from ranavirus can exceed 90% in affected populations, with deaths occurring at all life stages and peaking in summer months. Populations that encounter the disease tend to decline substantially over time.

Urban common frog populations face additional pressures. Roads and buildings act as barriers to movement between groups, reducing genetic diversity and leading to higher rates of developmental abnormalities and mortality in city-dwelling frogs compared to rural ones.

Despite these pressures, the common frog is listed as a species of least concern on the IUCN Red List of Threatened Species.

This is general awareness only, not veterinary advice. Always consult a vet about your pet's health.

How long does a common frog live?

Common frogs typically live between six and eight years in the wild. They reach sexual maturity at around three years old, which is also when they return to the pond where they were born to breed for the first time.

How can I tell a common frog from a common toad?

Common frogs have longer legs, moist smooth skin, and move by hopping. They also lay their eggs in clumps. Toads have shorter legs, dry warty skin, crawl rather than hop, and lay their eggs in long strings.

Is the common frog found all over the UK?

Common frogs are found throughout much of Europe, including the British Isles, and can live in both rural and urban areas. They are a familiar visitor to garden ponds, particularly in spring when they come to breed.

Do common frogs carry any diseases?

Common frogs can be affected by ranavirus, a serious disease that has caused significant population declines. Moving frogspawn, tadpoles, or frogs between ponds is known to risk spreading such diseases.

What do common frogs eat?

Adult common frogs eat whatever prey is most available, including crane flies, moth and butterfly larvae, woodlice, beetles, slugs, snails, and earthworms. Larger frogs are able to take a wider range of prey than smaller, younger ones.

Are common frogs active at night?

Yes, common frogs tend to hide in damp places during the day and come out to hunt at night. They are generally active for much of the year, only going into hibernation during the coldest winter months.

Common frogs can lighten and darken their skin to match their surroundings, and they have many predators, including herons, otters and stoats.

During the breeding season, male common frogs often take on a greyish-blue colour, while their throats turn white. It is a brief but striking transformation in an animal that spends most of the year in quiet, earthy tones.

The common frog is found further north than any other amphibian in its region, living as far into the Arctic Circle as northern Scandinavia. Rather than freezing solid to survive, it relies on finding warm microhabitats and sometimes hibernates in groups to share body heat.

A cluster of common frog eggs is more than just a bundle of spawn - the mass raises the temperature of the embryos relative to the surrounding water, which matters because tadpoles develop faster at higher temperatures.