_ZvO7Ih.webp)
Rana dalmatina, the agile frog, is a slender member of the family Ranidae, named for the long jumps its build allows. It is found across much of Europe, including France, parts of Germany, Denmark, Sweden, Italy, Spain, Poland, the Czech Republic, Slovakia, Austria, Hungary, the Balkans, Greece and around the Black Sea, with a further population on Jersey in the Channel Islands, though it has died out on Guernsey and mainland Britain.
Identification
Males rarely grow larger than 6.5 cm, while females can reach up to 8 cm. The body is fat through the middle but carries long limbs and a pointy snout, and the hind legs are unusually long, letting the frog jump up to two metres in a single leap, further than similar frogs manage. The back is light brown, reddish-brown or light greyish-brown with very little contrast, marked by dark brown, triangle-shaped spots running from the temple to the eardrum; the underside is white and without spots. In the breeding season, males often turn dark brown. A closer look at the eye shows horizontal pupils and an upper iris that is lighter and gold in colour, while the tympanum is about the same size as the eye’s diameter.
Habitat and range
The agile frog prefers light deciduous mixed forests with plentiful water, and tolerates nearby open land when it stays connected to the forest by shrubs; it can also live in dry, warm forests well away from water, since of the three Middle European Rana species it favours warmth and dryness the most. Its range spans France, Germany, Denmark, Sweden, Italy, Spain, Poland, the Czech Republic, Slovakia, Austria, Hungary, the Balkans, Greece and the Black Sea coast, plus Jersey, where the population survives despite the species dying out on Guernsey and on mainland Britain.
Behaviour and breeding
In Central Europe, spawning usually happens in the first twenty days of March, though cold weather can delay it. Males call with a fairly quiet “rog … rog … rog” that can run up to twelve seconds, sounding something like a clucking chicken, and they often call from under water rather than at the surface. Unlike the moor frog and the common frog, the agile frog does not lay all of its spawn in a single clump: a female’s 450 to 1,800 eggs, each about 1.5-2.1 mm across, attach to tree branches, roots or plant stems at depths of 5-40 cm, rarely sinking to the pond floor. Adults hunt arthropods such as caterpillars, spiders, millipedes, flies, beetles, cicadas and springtails, while the tadpoles that hatch from the eggs feed on plant material.
Conservation
The IUCN category is shown in the facts box above. In Britain, the species is judged far more precarious: the Great British Red List assesses it as Critically Endangered, reflecting a local history rather than its wider European status. Remains found near Gosberton, Lincolnshire, dating to the Middle Saxon period, around 600-950 AD, confirm the frog was once native to Britain, where it is thought to have survived until around 1800 before centuries of deforestation and the drainage and enclosure of forests wiped it out. On Jersey, the last stronghold in the Channel Islands, the population was reduced to a single site by the late 1980s after habitat loss and a 1987 pesticide spill; spawn has since been head-started at Jersey Zoo and used to reintroduce the species to Ouaisne Common.
Similar species
The agile frog shares much of Middle Europe with the common frog, Rana temporaria, and with the moor frog, Rana arvalis, and the three are easily confused. Build is the clearest tell: the agile frog’s long limbs, pointy snout and unusually long hind legs let it jump further than either relative. Breeding habits separate them too, since the agile frog spreads its eggs across several separate attachment points rather than laying them all in one clump, the strategy both the common frog and the moor frog use. Habitat is the last clue: of the three, the agile frog is the one most drawn to warm, dry forest, while its relatives sit closer to water more often.