Predicting the effects of agricultural change on farmland bird populations in Poland

Measures of bird species richness, and the abundance or distribution of 20 farmland species, 12 of them species of European conservation concern (SPECs), were modelled as a function of a number of habitat variables in six regions of Poland using information-theoretic methods. The strongest positive predictor of species richness of all species, of SPECs and of farmland specialists was the length of woody edge habitat. There was a curvilinear relationship between cereal cover and species richness measures, with total species richness reaching a peak at about 30% cereal cover. Species richness was therefore highest in areas of mixed farming with a high proportion of woody edge habitat. The length of woody edge habitat was also the strongest predictor of the abundance of individual species, although the direction of this relationship varied. This modelling approach generated predictions about changes in bird species richness and abundance in response to agricultural change across Poland. Mixed farming with a high proportion of grassland and woody edge habitat is likely to maintain many of Poland's important farmland bird populations, but species-specific prescriptions will be needed for those species which avoid woody edge habitat.