Studies on the habitat preferences of Reed Bunting Emberiza schoeniclus L. conducted on an intensively farmed (93% arable land) area (54 km²) of Wrocław Plain (Lower Silesia Province, SW Poland, 17°03’E, 51°02’N) have shown that during the breeding season this species was found mainly in abandoned crop fields profusely overgrown with Tanacetum vulgare, Artemisia vulgaris and Solidago sp. Wintering birds remained in strongly weeded crops (arable habitats). The presence of breeding pairs (n = 37) was recorded within 24 (36%) out of the 67 longterm fallows (total area = 336.88 ha, average area = 5.03 (± 10.52 SD) ha, range = 0.19 to 83.53 ha). The field size was the best predictor of the Reed Bunting abundance among the seven landscape variables describing the environmental diversity of a fallow (apart from the field size, these were the lengths of: treebelts, hedges, railway embankments, roads, ditches and borders with adjacent crop fields). In the model of multiple regression after stepwise forward selection this variable explained as much as 86% of the variance in Reed Bunting abundance in that biotope. Wintering birds (total of 367 specimens) were discovered in 43 (37%) out of the 117 studied fields, comprising seven arable habitats – cereal stubbles, young and old fallows, root crop stubbles, fruit and vegetable crops, bare tilled and winter cereals (average area = 2.81 (± 2.31), range = 0.23 to 12.72 ha). The highest density and frequency (i.e. percentage of one field type where at least one Reed Bunting was recorded) were found in strongly weeded fruit and vegetable crops and in root crop stubbles (with abundant Amaranhtus retloflexus, frequency respectively 89 and 64%), in young fallows (with a series of annual weed species, including the abundant Chenopodium album; 77% frequency) and in cereal stubbles (with Chenopodium album and Setaria viridis; 50% frequency). In winter season birds were recorded only in 20% of old fallows. No wintering birds were found in winter cereals, nor in ploughed fields. The large area of root crops in Poland and the related spreading of weeds, such as Amaranthus and Chenopodium, coupled with long-term set-aside may compensate many granivorous birds, wintering in Europe on farmland, for the considerable reduction in their winter food resources, caused by the massive introduction of winter cereals.
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