Danish initiative helps revive near threatened bell frog population on Als island

The Danish population of bell frogs is in a dire situation, listed as “near threatened” on the Danish Red List of endangered animals. An initiative on the Danish island of Als aims to change this. Last year, the municipality of Sønderborg re-released 900 bell frogs in Kær Vestermark. Bent Albæk, a biologist from Sønderborg, was initially anxious about how the frogs would fare in the new habitat, but his concerns have been put to rest. They have found a significant number of bell frogs at individual ponds in the area.

Bell frogs, characterized by their gray-green color and distinctive orange markings on their underside, have a unique croak, reminiscent of the sound one makes when blowing into a glass bottle.

The local project involves releasing 900 frogs each summer for three years. This year, the Nature Agency of Southern Jutland is undertaking a similar project. This means that in three years, a total of 5,400 bell frogs will have been reintroduced to Als.

The Nature Agency of Southern Jutland is releasing their 900 bell frogs into two other areas on Als. Lonnie Jessen, a biologist with the agency, has been working for over a year to prepare for the frogs’ big move.

It’s been over 80 years since bell frogs were last seen on Als. The species was driven away by expanding infrastructure and changes in agricultural land. But now, efforts are being made to bring the bell frog back to Als, Jessen says.

The project is being carried out in collaboration with Danish environmental consultancy firm Amphi Consult. The company captured the eggs in Østfyn and then raised the animals from tadpoles to bell frogs.

The frogs are now large enough to move into the pond at Egetofte. Over the next two years, the bell frogs will be joined by a new batch of frogs. For Jessen, the success criteria is to hear the first mature males croaking in a few years, signifying that they can reproduce and sustain the population on their own.