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Breeding pool enhancements keep the toads singing

27.05.2024, 10:30 | Blog

A 1-hectare pool landscape in Härkingen in the canton of Solothurn that serves as a vital spawning ground for endangered toads has been restored and enhanced with the support of the Alpiq Green Fund. The habitat will also benefit several other species that have become rare to the region.

The natterjack toad and midwife toad are rare species, smaller than the common toad, that lay their eggs in warm, shallow pools of water or carry them on their back until they hatch. While many of us may not have seen these toads, the chances are that we’ve heard their song. In the spring, the males sing together at night to attract females. Their calls can be heard over a kilometre away! Sadly, the nocturnal chorus of these ‘boy bands’ is being heard less frequently nowadays. The two species are on the red list in Switzerland and considered critically endangered.
As Peter Jäggi, President of the Härkingen Nature and Bird Protection Association, explains, these toads’ chances of survival depend critically on the presence of suitable bodies of water: “The natterjack toad and the midwife toad are pioneer species, which means that they use newly created, temporary bodies of water as spawning grounds. When these bodies of water dry out, it harms their natural enemies, giving the toads a better chance of survival as their spawn can develop and they can form viable populations.”

Ecological enhancement of landscape

Following the heatwave of summer 2018, the clay-lined pools maintained by the Härkingen Nature and Bird Protection Association were no longer able to hold water and urgently needed to be rehabilitated. A two-year project was launched to build new drainable pools, rehabilitate the existing pools and seal others with pressed sludge. The construction work and the creation of ruderal sites restored the habitat to pioneer status. The pool landscape connects the nearby nature reserves “Ägerten” and the “Gunzger Allmend”. 
An emphasis was placed on using local materials. Stones from the neighbouring gravel pit were used, while material from the neighbouring forest was used to create the deadwood structures. The pools were sealed with clay from the excavation of the new pools or pressed sludge from the neighbouring gravel extraction site.
 

The Alpiq Green Fund's contribution to preserving ecosystems

This ecological enhancement perfectly matches the objectives of the Alpiq Green Fund, which aims to provide financial support to regional projects aimed at environmental revaluation and improvement measures – particularly with a focus on water-related projects. The Alpiq Green Fund contributed CHF 100,000 towards the total project costs of around CHF 250,000.

For Peter Jäggi, the contribution by the Alpiq Green Fund plays a vital role in protecting ecosystems. “We’re delighted that Alpiq Green Fund has supported us to create these new spawning waters,” he says. “The existence of species like the natterjack and midwife toads is something precious. It’s important that we all work together to ensure their survival.”

When it comes to protecting biodiversity, it’s clear that all the involved stakeholders, including the toads themselves, are singing as one. We look forward to hearing their nighttime chorus for a long time to come.

Benefits for many different species

The project celebrated its completion in mid-May 2024, marked by a celebration involving representatives from the Härkingen Nature and Bird Protection Association, Alpiq, the Swiss Landscape Fund, the Civic Community of Härkingen, Bird Life Switzerland and local sponsors.

Participants were able to see how most of the woody plants at the clay pool landscape have been removed to create sunny habitats and the terrestrial habitat has been upgraded with wood and stone structures.

The enhancement of the site has also enhanced biodiversity in the region by creating a more liveable habitat for grass snakes, common toads, grass frogs, alpine and palmate newts, dragonflies as well as various bird species such as the red-backed shrike.