Broedvogels van de polder Matsloot in 1986-2009: Een afgetakeld weidevogelgebied aan de vooravond van moerasontwikkeling

In the course of the eighties of the past century Staatsbosbeheer started buying land in the polder Matsloot, a reclaimed valley bog area in Northem-Drenthe (Fig. 2). In 2010 the whole surroundings of the Leekstermeer in Drenthe are owned by this organisation (Fig. 1) that manages nature areas. On the meadows no fertilisers were added and the grass was mown at least once a year in order to improve botanical conditions. In general botanical goals were not achieved en in the near future the area will be used to cache water and turned into a swamp. At least partly due to the management, numbers of meadow birds almost instandy decreased sharply and in 2009 nearly all species had disappeared (Fig. 3-4). After a short period of higher numbers, waterbirds followed the same pattern (Fig 5). Instead of meadow and water birds, recendy other species like Common Reed Bunting, European Reed Warbler, European Stonechat and Bluethroat colonised the area. Meadow birds in the direct surroundings of the study area, on meadows that were agriculturally used, the decrease started later, but also these areas are nowadays devoid of meadow birds. Probably only under special management of meadows it will be possible to maintain a population of meadow birds, as can be noted in Fig. 6.