Wader breeding densities across European habitats

Wading birds can be found breeding in a myriad of habitats and ecosystems across Europe that vary widely in their land-use intensity. Over the past few decades, wader breeding populations have declined steeply in habitats ranging from natural undisturbed ecosystems to intensively managed farmland. Most conservation science has focused on factors determining local population size and trends which leave cross-continental patterns and the associated consequences for large-scale conservation strategies unexplored. Here, we review the key factors underlying population decline. We find land-use intensification in western Europe and mostly agricultural extensification and abandonment in northern, central and eastern Europe to be important drivers. Additionally, predation seems to have increased throughout the breeding range and across all habitats. Using collected breeding density data from published and grey literature, we explore habitat specificity of wader species and, of the most widely ..., To examine which habitats waders use for breeding in their main distributional range in Europe, how this differs between species and whether different habitats support different population densities, we searched published papers for quantitative data that could be used to calculate breeding densities. Initially, we performed searches of peer-reviewed scientific articles reporting densities of breeding waders published between 1945 and 2018 using ISI Web of Science Core Collection (WoS) and Elsevier Scopus databases by using a specific combination of related keywords (see Appendix 1 for more detailed information). We only used studies that met the following requirements: (1) the study reported breeding pair density data or gave a number of breeding pairs for a certain specified area from which a breeding density estimation could be calculated; (2) the study described which methodology was used for surveying breeding birds; (3) the study specified the habitat type or vegetation compositio...,