Habitat selection of the Ortolan bunting Emberiza hortulana in Poland: predictions from large-scale habitat elements

The Ortolan bunting Emberiza hortulana was censused in Poland during the Common Breeding Birds Monitoring Project in 2003–2009. Data from 683 monitoring polygons, covering in total more than 0.23% of the country, were used in the analysis. Based on the data and environmental information gathered in GIS databases (Corine land cover “CLC2000 and 2006” database, digital elevation model “GTOPO30” dataset, “Wordclim” dataset, and NDVI dataset), we modeled a habitat- and spatial-related variation of the Ortolan bunting’s presence. Birds were recorded in 13.2% grid cells. The mean density was 0.5 individual/km². We modeled the spatial presence of birds using multivariate adaptive regression splines (MARS). Then models were cross-validated to check their consistency. The environment-use model shows that the Ortolan bunting prefers extensively cultivated farmland dominated by non-irrigated arable fields, small coniferous and mixed forests, complex cultivation patterns, and meadows. The preferred areas are located on lowlands in western and central parts of the country where the climate is the driest and warmest. Such a repeatable spatial pattern model of the population helped to create a predictive map of the Ortolan bunting’s presence in Poland. The general rule is that the probability gradient of its presence increases from the northeastern part of the country to the central and southwestern parts of Poland. Additionally, the Ortolan bunting avoids severe continental climate and regions with dense ground-level vegetation.