Yellow-Bellied Toad

There are three places in Luxembourg where you can find a yellow-bellied toad. Three. That's it. The entire national population of Bombina variegata lives in three small pockets of the country, and without intervention, even those might disappear.

SICONA, the inter-municipal nature conservation association based in Olm, has decided that three is not enough. This spring they brought in ten adult toads from Germany, collected their spawn, and raised the eggs in monitored water tanks. After two months of development, the tadpoles are released into suitable habitats in the wild.

The timing of release depends on the toads' development, the weather, and water levels. As biologist Liza Glesener explains, the weather has a major influence: the period from egg-laying to hatching can vary between two and ten days, and it takes 37 to 67 days before the tadpoles develop their hind legs.[1]

The habitat problem

The yellow-bellied toad is picky about where it lives. It needs shallow, temporary bodies of water, the kind that form in puddles and ruts after rain. These pools dry out quickly during droughts, which is catastrophic if your tadpoles are still developing in them. In a summer like this one, with heatwaves across the region and wildfires in neighbouring Belgium, that's a real threat.

SICONA is addressing this by creating new bodies of water and adapting existing ones to the species' needs. Some are simple dug holes. Others are special toad ponds where water levels are maintained for longer periods and topped up when necessary.

Not the first try

SICONA has been breeding and releasing endangered species for over ten years. The approach has worked before: the European tree frog, once found at a single location, has now spread to more than 100 bodies of water across the country.

The yellow-bellied toad is harder. A previous reintroduction attempt released around 1,000 animals. About 100 survived. Drought, predators, and local conditions all work against the small population. The odds are not great, but SICONA's plan is to keep going: over the next five years, they want to introduce toads to one or two additional sites each year, slowly building a population that can sustain itself.

Why it matters

Amphibians are indicator species. When they start disappearing, it means something is wrong with the water, the soil, or the broader ecosystem. A country that loses its yellow-bellied toads is losing more than a frog with a colorful belly. It's losing evidence that its wetlands and temporary pools are still functioning.

Three sites. Ten imported adults. Five years of planned releases. It's a slow, careful effort, and success is not guaranteed. But the tree frog came back from a single site to over 100. Maybe the toad can do something similar.