The black tern in bogs and marshes

Numbers of black tern have plummeted, and despite measures being implemented, the species is not recovering.

Trends

Around 1950 there were about 15 000 breeding pairs of the black tern in the Netherlands. The present figure is less than 10% of that total and has remained more or less stable since 1993.

The black tern occurs mainly in bogs in carr peat areas and in marshes in the river region. For nesting, the species requires water with a vegetation of water soldier, with insect-rich grassland nearby, where it can search for food. Water soldier grows in bogs, marshes and in farmland ditches that are growing over.

Between 1960 and 1990 water soldier has dwindled dramatically, because of the eutrophication of surface water. However, recently it has been recovering. The black terns are also nesting on the artificial rafts that have been placed in water as a substitute for water soldier. In spite of this, numbers of black tern are not increasing, possibly because of a shortage of food (particularly of large insects) in the breeding season. The species is also disturbed by water recreation: sometimes boats run over the nests, or their wake washes eggs out of the floating nests.

The black tern is on the Red List of birds.