The black tern (Chlidonias niger) is a small, dark tern. Its English name comes from the colour of its feathers. As a migratory bird, it spends the winter on the west African coast. However, its breeding area extend from southern Spain via north-western, central and eastern Europe to far into Russia. Shallow and swampy lakes, ponds and oxbow lakes with lots of vegetation are sought out for breeding. Water bodies with dense flowering or floating leaf vegetation, such as water lilies and water pineapple, are especially preferred. They then act as floating islands for the nest. But other plants can also be used for this. The black tern mainly eats small fish and insects. Dragonflies are particularly important for rearing the young.
In North Rhine-Westphalia, the black tern is at risk of extinction. Currently, it only breeds in the Lower Rhine region. There, it can be found in the ““Bienener Altrhein, Millinger and Hurler Meer and Empeler Meer” and “Altrhein Reeser Eyland” nature conservation areas. In the project area, there are 24-44 breeding pairs of black tern (2011-2018). The current population is maintained only by providing artificial nest rafts. Natural breeding occurs only very rarely at the moment. Earlier, the breeding habitat of the black tern on the Bienen Old Rhine comprised the sparsely vegetated marginal areas of the broadleaf cattail, as well as the floating leaf vegetation. Descriptions from the 1970s bear testimony to this. The marginal areas with sparse vegetation as well as areas of decomposition, in which the dead material was used as a nesting place, were populated. By developing reeds and floating leaf plants, the range of natural breeding places for the black tern should be greatly enlarged so that natural breeding will be possible again. As a result, long-term species conservation measures provided by humans in the form of artificial nesting aids can be dispensed with. Since the reeds, which is an equally important reproduction and retreat space for fish and dragonfly fauna, the food available to the black tern is also encouraged.