Effects of management intensity and orchard features on bird communities in winter

The knowledge and conservation of diminishing valuable habitats in agricultural landscapes are of key importance in saving declining farmland biodiversity. One of these habitats is the traditional orchard whose role in supporting birds is still poorly known, especially in winter. We counted birds in 106 orchards differing in management intensity (abandoned, traditional, and intensive) during December 2009 and January 2010 in Wielkopolska, western Poland and measured site characteristics and composition of surrounding landscapes for every orchard. Old abandoned and traditionally managed orchards had significantly higher bird species richness than intensive ones. Irrespective of orchard type, bird species richness as well as density were positively influenced by the cover of unmown herb layer in orchards and tree diversity. Tree and fruit densities positively affected bird species richness and density mainly in abandoned orchards while in other orchard types the effect of these variables was less pronounced. Land cover diversity in a landscape had a positive effect on species richness and density mostly in abandoned orchards and we believe that this effect reflects the elevated utilization of such orchards by birds from the surrounding landscape. Thus, abandoned, as well as traditionally managed orchards seems to be especially important habitats that offer food source and refuge for wintering birds and should be protected. We propose to diversify fruit production by planting various tree species, leaving part of the herb layer unmown and several trees unharvested in intensive orchards in order to improve suitability of modern orchards for birds.