Bird monitoring (Wadden Sea)
Since 1994 all coastal birds breeding in the Wadden Sea are recorded at representative sample sites and additional sites in Schleswig-Holstein each year. This kind of monitoring is conducted throughout the entire Wadden Sea from the Netherlands to Denmark (Hälterlein et al. 1995), and the resulting reports are regularly published (Rasmussen et al. 2000, Koffijberg et al. 2006).
Since 1992 comparative bird counts are carried out annually as part of scientific quality assurance (Blew et al. 2003). End of May/beginning of June several experts meet in one of the four Wadden Sea regions (Netherlands, Lower Saxony, Schleswig-Holstein or Denmark) in order to conduct comprehensive registrations and to count colonies of breeding birds jointly. These data are compared with each other and in the case of colony counts with, for example, clutch counts or aerial surveys.