Effects of grazing regime and vegetation changes on breeding birds in salt marshes of the Schleswig‐Holstein Wadden Sea National Park and Halligen

Abstract

The effects of grazing and abandonment in salt marshes on breeding bird diversity have been a perennial issue in Germany’s Schleswig‐Holstein Wadden Sea National Park during the last 25 years. When the national park was established in 1985, 80% of the salt marshes were intensively grazed by sheep. By the early 1990s, grazing in the park had been significantly reduced, and in some areas ceased. After an initial increase in plant diversity resulting from these changes in grazing regime, large mono‐dominant stands of late successional plants occurred in some areas and plant diversity decreased once again. Because salt marshes are an important breeding habitat for birds, these changes in grazing regime and plant diversity affected avian diversity within the park. The responses of breeding birds to habitat changes were various and yet no study has specifically addressed these responses on a large scale and over a long time period. In this study existing vegetation mappings and bird count data were used to address the effects of changes in grazing regime and vegetation on breeding birds in four periods from 1988–2006 at two different spatial scales.