Population crash of the ortolan bunting Emberiza hortulana in agricultural landscapes of southern Finland

The ortolan bunting Emberiza hortulana is a bird species that has shown a particularly dramatic decline during recent decades within the agricultural areas of Europe. We studied the population density changes and environment associations of the ortolan bunting within agricultural landscapes in southern Finland, from territory to landscape scale, in 1984–2002. The crash of the ortolan bunting population took place synchronously during the early 1990s in all the subpopulations, resulting in a total decrease of 72% by the end of the study period. The decline was associated with the amount of small-scale environmental heterogeneity and with agricultural practices. Bushor treecovered ditches and springtime non-vegetated fields (mainly spring cereal and root crops) were the habitat factors showing a clear positive effect on the occurrence of the ortolan bunting. However, the European-wide decrease of the ortolan bunting is probably also due to changes in migration and wintering areas. All these factors should be taken into consideration when planning conservation measures.