Wader breeding densities across European habitats
Silva-Monteiro, Miguel (2023), Wader breeding densities across European habitats, Dryad, Dataset, https://doi.org/10.5061/dryad.xpnvx0kkp
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.
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 composition of the surveyed area; (4) the study mentioned the year(s) of survey. We focused on continental Europe, including the United Kingdom and Ireland but excluding Iceland. Although southern Europe has some locations supporting breeding waders (e.g. Tinarelli and Bacetti, 1989; Valle and Scarton, 1996), we were not able to find breeding density information in any country located in the Mediterranean area. In total, we found 32 scientific articles containing 984 breeding densities that included 26 wader species and 5 countries in the period 1967–2015. In line with previous observations (Tryjanowski et al., 2011), we found most studies originated from the United Kingdom (65% of all data). The other represented countries were Poland (10%), Finland (11%), Sweden (10%), European Russia (3%) and France (1%). Surprisingly, hardly any studies were found from countries such as the Netherlands, a renowned stronghold of wader species such as black-tailed godwit, northern lapwing and Eurasian oystercatcher (Roodbergen and Teunissen, 2019), with various scientific groups working on meadow bird ecology. In most countries, it is common practice to report results of breeding wader surveys in local reports or journals in the national language. We therefore decided to include grey literature in our review, acknowledging that this biases our findings somewhat to languages that are accessible to the authors (Dutch), mostly from northwestern Europe. Data from non-peer reviewed conference papers and government reports were searched on common search engines such as google scholar database using the same combination of keywords as was used for peer-reviewed papers. Our final dataset contained 87 studies, 29 species and 8 countries with a total of 2,744 breeding density observations
Wageningen University and Research