Field use by farmland birds in winter: an analysis of field type preferences using resampling methods

Abstract

This study examined the habitat preferences of 26 field-feeding bird species wintering on mixed, lowland farmland. Resampling methods were used to determine for each species whether the total number of birds recorded on each field type over the winter differed from that expected if birds were distributed randomly. Grazed grass fields were generally preferred by invertebrate-feeding species and avoided by seed-eaters. Ungrazed grass fields were used relatively more by seed-eating species, and less by invertebrate-feeders than grazed fields. Cereal and oilseed stubbles were strongly preferred by seed-eating species, in some cases to the virtual exclusion of other field types. Winter cereals were almost universally avoided, although there was some evidence that a few species made more use of organic cereal fields than those under conventional management. These results are consistent with likely variations in invertebrate and seed food availability between field types, and suggest that a mixed farming landscape which combines stock grazing with an arable regime that maintains some over-winter stubbles will support higher numbers and a higher species diversity of field-feeding birds than landscapes dominated by autumn-sown crops or pasture. Over-winter stubbles are extremely important feeding habitats for seed-eating passerines. On set-aside land, regeneration of a vegetation cover from stubble is thus likely to yield much greater benefits for wintering seed-eating birds than sown grass covers.