Habitats supporting wader communities in Europe and relations between agricultural land use and breeding densities: A review

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 distributed species, how breeding densities change across a land-use intensity gradient. We found that two-thirds of all examined wader species have relatively narrow breeding habitat preferences, mostly in natural and undisturbed ecosystems, while the remaining species occurred in most or all habitats. The most widespread generalist species (black-tailed godwit, northern lapwing, common redshank, Eurasian oystercatcher, common snipe and ruff) demonstrated peak breeding densities at different positions along the land-use intensity gradient. To conserve both diverse wader communities and viable meta-populations of species, a diversity of habitats should be targeted ranging in land-use intensity from natural ecosystems to medium intensity farmland. Alongside, strategies should be designed to moderate predation of wader clutches and chicks.