Habitat parameters affecting the distribution of breeding meadow birds in grasslands of Bremen

The continuing rapid decline of Europe’s breeding meadow wader populations in the last three decades is largely attributed to agricultural intensification and the resulting deterioration of habitat quality in cultivated grasslands. With the widespread destruction of their former natural habitats, extensive and dynamic wetlands, these birds have found refuge in man-made grasslands. Of vital importance for these birds in meadow and pasture ecosystems are the habitat parameters groundwater level, vegetation structure and openness on a landscape scale. In this study, landscape elevation, structure and openness derived from satellite imagery, combined with annual data on agricultural use and conservation management were used to analyse nest site selection in five species of meadow waders in the Blockland grassland area in Bremen from 2009 – 2012. Based on the statistical modelling of these data the results show that the wader species Common Snipe (Gallinago gallinago L.), Curlew (Numenius arquata L.), Redshank (Tringa totanus L.), Northern Lapwing (Vanellus vanellus L.) and Black-tailed Godwit (Limosa limosa L.) especially prefer low-lying fields without trees in the vicinity for nesting. Also, the results show that flooding polder areas in spring, together with extensive use, strongly increases site attraction for breeding meadow waders. Furthermore, with an increasing number of small water bodies the fields in the study area became more attractive as nesting sites for the species analysed here. On the contrary, a negative effect on nest site selection in these birds was evident for fields close to power-lines and on intensively used meadows (more than three cuts per year). The agri-environmental scheme “KoopNat”, that offers contracts to farmers for adopting practices suitable for meadow breeding birds in the study area, did not show an effect on the settlement or abundance of the breeding bird species analysed here. For future management aiming to attract meadow waders for breeding in the area, removing trees close to low-lying fields and clearing and creating small water bodies promises to be effective. Raising groundwater tables and flooding fields in spring, together with long-term extensive use in grasslands will potentially help to reverse the ongoing declines of meadow wader populations in central Europe.