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

Abstract

The continuing rapid decline of Europe’s breeding meadow wader populations in the last three decades is largely attrib uted to agricultural intensification and the resulting deterio ration 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 manmade 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 to 2012. Based on the statistical modelling of these data, the results show that the wader species Common Snipe (Gallinago gallinago L.), Eurasian Curlew ( Numenius arquata L.), Common 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 waterbodies, the fields in the study area became more attractive as nesting sites for the species under study. In contrast, a negative effect on nest-site selection in these birds was evident for fields close to power lines and on intensively used meadows (three or more cuts per year). The agri-environmental scheme ‘KoopNat’, which 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 under study. For future management aiming to attract meadow waders to breed 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.