Common Frog: where and when to see them

The Common Frog is a widespread European amphibian found in both the Rhine and Seine river basins. Despite its name, its appearance is highly variable, with brown, grey, olive and reddish individuals all occurring. Adults spend much of the year on land, returning to freshwater to breed. Along river corridors, they are more closely associated with damp bankside habitats and nearby ponds than with the main flowing channel. Their presence depends on suitable breeding water and sheltered, moist places on land.

Size

Adults usually measure 6–9 cm from snout to vent, with females generally larger than males.

Weight

Adults typically weigh around 20–80 g, depending on size, sex and season.

Lifespan

Usually 5–10 years in the wild.

Status

Least Concern (IUCN).

Common Frogs are generally most active at dusk and at night, although they may also emerge by day in cool, wet conditions. Outside the breeding season, they usually live individually and shelter among vegetation, leaf litter or other damp cover. In late winter or spring, adults move towards breeding sites, sometimes gathering in large numbers. Males give soft, low-pitched calls rather than the loud croaks associated with some other frogs. During mating, the male grips the female behind her forelegs in a hold called amplexus. Females lay clumps of spawn, and the eggs are fertilised externally. Tadpoles develop in the water before metamorphosing into small frogs. In winter, Common Frogs become inactive in frost-protected shelters on land or, where conditions allow, underwater.

• Common Frog spawn forms jelly-like clumps, unlike the long strings laid by Common Toads.
• Males develop dark pads on their thumbs that help them grip females during breeding.
• Common Frogs absorb water through their skin rather than drinking with their mouths.
• The species occurs north of the Arctic Circle in Scandinavia.

Wildlife opportunities depend on the river reach, water levels and species. River-specific viewing months have not been confirmed; general species seasons are not a local sighting forecast.

Common Frogs occupy damp woodland, grassland, gardens, marshes and other habitats with suitable shelter. They breed mainly in still or slow-moving freshwater, including ponds, shallow pools and quiet ditches. In the Rhine and Seine valleys, floodplain ponds and wet meadows can provide suitable habitat away from the main river current. Dense vegetation and shaded ground help them avoid drying out during their terrestrial life. Fast-flowing channels, exposed quays and heavily engineered banks are generally less suitable than sheltered waterside habitats.

Adult Common Frogs eat a wide variety of invertebrates, including insects, spiders, slugs and earthworms. They usually capture prey on land, using their sticky tongue or jaws. Tadpoles graze on algae and consume decaying organic material, but also take animal matter when available. After metamorphosis, young frogs feed on small invertebrates.

Common name

Common Frog

Scientific name

Rana temporaria

Animal group

Amphibians

Size

Adults usually measure 6–9 cm from snout to vent, with females generally larger than males.

Weight

Adults typically weigh around 20–80 g, depending on size, sex and season.

Lifespan

Usually 5–10 years in the wild.

Status

Least Concern (IUCN).

Identification

Look for a relatively smooth-skinned frog with long hind legs, a blunt snout and a dark patch behind each eye that includes the eardrum. Two raised folds run along the sides of the back. Colour is highly variable, and the back and legs often carry darker spots or bars, so colour alone is unreliable. Common Toads are generally wartier and shorter-legged, while distinguishing Common Frogs from similar brown frogs, such as the Agile Frog, may require a clear view of several features.