Habitat selection by Skylarks Alauda arvensis wintering in Britain in 1997/98

The results of a national survey of wintering Skylarks Alauda arvensis unde rtaken by the British Trust for Ornithology (BTO) between November 1997 ari d February 1998 are reported here. Over three visits, volunteers counted Sk ylarks and mapped habitats in 541 1-km squares selected from the Skylarks w inter range based oil BTO Winter Atlas data and a stratified random samplin g approach. Four landscape strata were defined from the Institute of Terres trial Ecology landscape classification: arable, pastoral, marginal upland a nd saltmarsh. The survey counts underestimated Skylark abundance, but were good measures of relative abundance across habitat types. The two best pred ictors of Skylark presence-absence at the landscape scale were the availabi lity of coastal and farmland habitats. Squares with saltmarsh had the highe st densities and occupancy (80% of squares). At the patch scale crop stubbl es, especially weedy cereal stubbles, were used significantly more than exp ected by chance. Oilseed rape was positively selected whereas cereal crops were used in proportion to availability and grazed grass was avoided. Skyla rks avoided fields smaller than 2.5 ha and selected fields larger than 7.5 ha. We estimate that in midwinter there may be less than 1-2 ha of weedy ce real stubble per 1-km square. We recommend the retention of over-winter stu bbles for the conservation of Skylarks arid other farmland birds, and resea rch oil stubble management and effects on grain availability and arable wee d regeneration on Skylark use.