Do Ecological Compensation Areas influence Population Trends of Farmland Bird Species in the Swiss Midlands?

27 Mar Do Ecological Compensation Areas influence Population Trends of Farmland Bird Species in the Swiss Midlands?

View Original

Abstract

English Abstract

We investigated whether the breeding numbers of 37 farmland bird species increased as expected after the implementation of ecological compensation areas which are part of the Swiss agro-environment scheme. Two surveys were conducted (1998–99 and 2002–03) on 23 study sites in the Swiss Midlands. Only part of the expected species were present on the study plots and mostly with low territory densities. Many species were particularly rare or missing entirely in grassland-dominated areas whereas they were more abundant in the climatically favourable arable areas. All species taken together showed a slight non-significant increase in number as well as territory density between the two surveys. The increase was caused mostly by species of least concern while populations of vulnerable species continued to decline. The reason for this moderate reaction to newly offered ecological compensation areas may be found in their low ecological quality. Moreover, especially valuable types of compensation areas were implemented only rarely. In summary, ecological compensation showed some, although only slight, positive effects. Its potential, however, is by far not fully exploited yet. The weakness of the system seems to lie in the lacking quality and spatial distribu