Heinz-Sielmann-Weiher, Nature reserve in Billafingen, Germany.

Heinz-Sielmann-Weiher is an artificial pond of about 1.3 hectares in the west of Billafingen, a district of Owingen. It lies between the L205 road to Seelfingen and the Mahlspürer Aach to the north, with the Unterfrickhof farm to the south. The pond is surrounded by field hedges, flower-rich margins, a roughly nine-hectare water buffalo pasture, ditches, pools, shallow-water hollows and reed beds.

The wetland was established in 2005 as a pilot project by the Heinz Sielmann Foundation under ornithologist Professor Peter Berthold's guidance. Its purpose was to restore habitat for water and meadow birds in the region.

The pond is named after Heinz Sielmann, the wildlife filmmaker and founder of the Heinz Sielmann Stiftung, which backed the project. Ornithologist Peter Berthold, who lives in Billafingen, initiated it as a pilot of the Sielmanns Biotopverbund Bodensee. The pond is a station on the roughly 4.5-kilometre Billafinger Naturlehrpfad, a nature trail used by visitors and local walkers.

The pond lies west of Billafingen between the L 205 road to Seelfingen and the Mahlspürer Aach, with the Unterfrickhof farm to the south. It is one stop on the roughly 4.5-kilometre Billafingen nature trail, which visitors follow on foot. Sturdy footwear helps, as the ground around the water can be muddy depending on the season.

The reserve is home to around 340 flowering plant species and serves as a nesting ground for white storks on specially built platforms. This stork presence makes the area a rare example of successful reintroduction in the region.