Black Tern conservation in Brandenburg
CABS artificial nest islands conservation project
The Black Tern’s nesting requirements are very special. The water body must be undisturbed, not too deep but also not too shallow and without currents, have lots of exposure to the sun and, above all, be rich in water plants. These black beauties build their nests on dead plants that float on the water’s surface. This preference for such a rare type of biotope nowadays has driven the Black Tern to the brink of extinction. Only some 1,000 to 1,300 pairs now breed on the waters of the North German Plain and the German population has declined by more than 50 % over the past 30 years.
The same is true of other European countries. The Black Tern is in marked decline in all western and southern European states; thankfully populations are (still) stable in the neighbouring eastern European countries. But even here the still wide-ranging natural countryside is threatened by intensive agricultural management and infrastructure development.
In order to help the endangered species CABS has constructed an artificial nest colony on the Pritzerber See nature reserve, a lake on the River Havel north-west of the city of Brandenburg.
In spring 2007, a 30 small rafts of reeds bound with wire were positioned on the lake from a rubber dinghy. In late winter 2008 an additional 60 small platforms were set out in the River Havel itself and in an oxbow lake of the River Elbe in Saxony-Anhalt. The lightweight artificial islands were anchored to the river bed with long lines, in order to compensate for changes in the water level after heavy rainfall. During the winter the nest platforms were removed to avoid damage during annual flooding.
The Black Terns arriving back from their winter quarters in May immediately accepted the new nest sites and in summer 2009 36 breeding pairs had occupied the platforms and raised 32 young. Black-headed Gulls (in 2009 30 Pairs) also bred in part of the colony.
In early summer this year (2010) a record number of platforms were occupied, a total of 63 nests.
The CABS tern colony is located just on the edge of the Havel renaturisation project, unique in Europe. Over the next few years an area of some 18,700 hectares (over 46,000 acres) of riverine pasture habitat, between Pritzerbe and the confluence of the Havel with the Elbe, will be returned to its natural state. This will include the restoration of numerous semi and complete oxbow lakes of the River Havel where the Black Terns can once again find their natural nesting habitat. Until then, CABS will extend the Pritzerbe See colony. An extension of the project in the Elbe Valley in Saxony-Anhalt near Tangermünde is also planned.
The project is funded exclusively through donations - we receive no assistance from public funds for our Black Tern conservation project.