The Nérac ponds are located in the communes of Altenach and Saint-Ulrich in the Sundgau. Dating from the 17th century, this group of 5 ponds, covering about 20 hectares, is a transitional area between the beech forest and the cultivated fields. Exploited until the 1970s, they were then sold to the Conseil Général du Haut-Rhin in the early 1990s. Their size and the absence of maintenance for several years allowed them to evolve towards a greater naturalness, despite their typical morphology of Sundgau fishing ponds. Thus, their steep banks only allowed the installation of a thin curtain of riparian vegetation. Only pond n°4 had a significant reed bed. Moreover, the constant water levels and the very low diversity of habitats were not conducive to the exploitation of the ponds by a varied fauna.
However, the ornithological monitoring carried out on this site has shown that more than a hundred species of birds use the Nerac ponds, either for nesting or for migratory stopovers. Rare species, such as the Remiz Penduline, the Osprey, the Harrier Saint Martin or the Grey Crane have been observed there. In addition, their location between the edge of the forest and the open field gave them a significant potential for hosting biodiversity.
A topoguide available at the Maison de la Nature du Sundgau located in Altenach or at the Tourist Office offers a 2h-2h30 walk to discover this site suitable for the observation of birdlife.