Cropland use by birds wintering in arable landscape in south-western Poland

The research carried out in SW Poland in winter 2002/2003 showed the presence of birds within 69 (59%) out of 117 studied fields (total surface = 329.3 ha). Birds were totally absent only from two (bare tilled and winter cereals) out of seven studied field types (the other were: cereal and oil-seed rape stubbles, root crop stubbles, vegetable and fruit crops, young and permanent fallows). In all inhabited field types the percentage of occupied fields (hereafter occupancy) ranged from 58 (permanent fallows) to 100% (fruit and vegetable crops). A total of 2256 individuals, belonging to 27 species were recorded. In all habitats the core of bird fauna was formed by the seed-eaters (from 84 to 98% of all birds). The most frequent species was reed bunting Emberiza schoeniclus (occupancy 37%), followed by pheasant Phasianus colchicus (occupancy 21%). The highest average bird density was recorded in fruit and vegetable crops (61.6 ± 32.7 individuals ha−1), and 20 times lower in permanent fallows. The average number of individuals found within a single field was also highest in fruit and vegetable crops. In permanent fallows, however, the highest share of insectivorous birds (7%) and predators (5%) was recorded.