Fire-bellied toads and green toads on the islands

Fire-bellied toad / 'klokkefrø' (Bombina bombina), green toad (Bufotes viridis), natterjack (Epidalea calamita), tree frog (Hyla arborea) on Lolland-Falster and Bornholm, moor frog. South Funen archipelago (Avernakø, Hjortø), East Funen (Klintholm), Enø/Zealand islands, Bornholm, Denmark.

Best time: 10 May – 15 Jun (May to June). Where: Avernakø (South Funen), Klintholm / Tårup, East Funen, Hjortø (protected island) (Denmark). Time of day: Fire-bellied toads call on warm sunny afternoons from about 15:00 and through the evening to midnight, above 15 °C.

• You can go on your own
• Low cost
• No binoculars needed
• Sound 4/5

Open it in the interactive calendarSunrise and sunset listening times for the day you pick, and the map.

When is the best time?

Peak: 10 May – 15 Jun. 10 May to mid June on warm, still evenings (bell-like 'klokke' chorus that gives the toad its Danish name)

Active from 15 Apr to 5 Jul (April to July) in a typical year.

Time of day

Fire-bellied toads call on warm sunny afternoons from about 15:00 and through the evening to midnight, above 15 °C; green toads and natterjacks are loudest after dark.

• Warm-afternoon calling: 15:00 → sunset
• Evening chorus: sunset → 00:00

What will you hear?

Fire-bellied toads' soft, bell-like 'oop... oop' in chorus from cattle ponds — from a distance like distant church bells; green toads' long trills; natterjacks ratcheting on the beach meadows; tree frog volleys on Lolland.

Binoculars?

No binoculars needed. Bell-like chorus from roadside ponds at dusk; a torch, not binoculars.

Where to go

• Avernakø (South Funen) — Heard in many places on the island on sunny evenings in late May; ferry from Faaborg; no cars needed. Map
• Klintholm / Tårup, East Funen — Restored ponds near Klintholm (LIFE project); good roadside listening from late April into July. Map
• Hjortø (protected island) — Tiny island with one of the best populations; sunny days in May–June; ferry from Svendborg. Map
• Enø / Dybsø Fjord (Zealand) — Green toads and natterjacks on the beach meadows; Bombina reintroduced in the area. Map

How to go on your own, and what it costs

Avernakø: ferry from Faaborg, listen from the island lanes on a warm evening. Klintholm/Tårup: roadside ponds off the Nyborg–Kerteminde road. Hjortø: ferry from Svendborg, day visits. Enø: the coast road and beach meadows. Roads, dykes and paths only; the ponds are on private land.

Cost: Free; island ferry fares (check current prices).

Field-recording notes

The klokkefrø is one of Denmark's rarest animals, kept alive by LIFE projects and pond restoration — all sites are on private farmland or protected islands; record from roads, dykes and paths, and never handle or net (Habitats Directive Annex II/IV). The call is quiet and low (around 500 Hz): omnis within 3–5 m of the pond edge on a windless evening above 15 °C. Island evenings are ferry-quiet; the East Funen sites are near the Nyborg motorway in some wind directions. Green toads are on the same islands and are much louder.

Sources

• Naturstyrelsen – LIFE Klokkefrø
• Klintholm I/S – info on the klokkefrø
• Kvæk.nu – the 11 Danish frog and toad calls

Similar spectacles

• Natterjack toad chorusUnited Kingdom · Amphibian chorus · peak 15 Apr–31 MayThe loudest amphibian in Britain — a rolling, ratcheting chorus audible up to 2 km away across dunes.
• Natterjack toad chorus on the Kerry dunesIreland · Amphibian chorus · peak 20 Apr–25 MayA loud, ratcheting 'rrrrRup, rrrrRup' chorus from dozens of males in shallow dune pools — the loudest amphibian in these islands — with the Atlantic surf behind the dunes and snipe overhead.
• Tree frog choruses of Zeeuws-VlaanderenNetherlands · Amphibian chorus · peak 1 May–31 MayA rattling, surprisingly loud 'kè-kè-kè-kè' chorus from hundreds of tree frogs around the old fortress moats and pools — audible across the polder — with marsh frogs and nightingales behind; the ramparts of Retranchement alone hold a few hundred.
• Fire-bellied toads, natterjacks and blue moor frogsGermany · Amphibian chorus · peak 25 Mar–7 Apr and 15 Apr–25 MayFire-bellied toad's melancholy 'uh...uh' by the hundred over shallow pasture ponds, moor frog's bubbling 'waug-waug' underwater chorus, natterjack's ratcheting trill carrying 2 km across dune slacks, tree frogs at full volume, bittern and crane in the background.
• Marsh frog & tree frog chorusesFrance · Amphibian chorus · peak 25 Apr–10 JunWall-to-wall marsh frog laughter from the Camargue ditches, ratcheting tree frogs from Brenne ponds, and natterjacks rolling across the Landes dune slacks.
• Frog nights in the Danube floodplain forestAustria · Amphibian chorus · peak 15 Apr–31 MayTree frog volleys and fire-bellied toads' soft hooting from the oxbows (Altarme), marsh frog laughter, night herons croaking overhead, nightingale and beaver tail-slaps; Danube barges as a slow low bed.

More: all spectacles in Denmark · frog and toad choruses · Denmark in May · Denmark in June