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

The results of a national survey of wintering Skylarks Alauda arvensis undertaken by the British Trust for Ornithology (BTO) between November 1997 and February 1998 are reported here. Over three visits, volunteers counted Skylarks and mapped habitats in 541 1-km squares selected from the Skylark's winter range based on BTO Winter Atlas data and a stratified random sampling approach. Four landscape strata were defined from the Institute of Terrestrial Ecology landscape classification: arable, pastoral, marginal upland and saltmarsh. The survey counts underestimated Skylark abundance, but were good measures of relative abundance across habitat types. The two best predictors of Skylark presence–absence at the landscape scale were the availability of coastal and farmland habitats. Squares with saltmarsh had the highest densities and occupancy (80% of squares). At the patch scale crop stubbles, especially weedy cereal stubbles, were used significantly more than expected by chance. Oilseed rape was positively selected whereas cereal crops were used in proportion to availability and grazed grass was avoided. Skylarks 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 cereal stubble per 1-km square. We recommend the retention of over-winter stubbles for the conservation of Skylarks and other farmland birds, and research on stubble management and effects on grain availability and arable weed regeneration on Skylark use.

[1]  Ralph T. Clarke,et al.  ITE Merlewood Land Classification of Great Britain , 1996 .

[2]  S. Baillie,et al.  The importance of variation in the breeding performance of seed‐eating birds in determining their population trends on farmland , 2000 .

[3]  R. Fuller,et al.  Classification of TM imagery in the study of land use in lowland Britain: practical considerations for operational use , 1990 .

[4]  A. J. Morris,et al.  Habitat characteristics affecting use of lowland agricultural grassland by birds in winter , 2000 .

[5]  Stephen J. Browne,et al.  Territory distribution and breeding success of skylarks Alauda arvensis on organic and intensive farmland in southern England , 1997 .

[6]  N. Aebischer,et al.  Factors determining winter densities of birds on Environmentally Sensitive Area arable reversion grassland in southern England, with special reference to skylarks (Alauda arvensis) , 1998 .

[7]  R. Freckleton,et al.  Predictions of biodiversity response to genetically modified herbicide-tolerant crops. , 2000, Science.

[8]  N. Davidson,et al.  Nature conservation and estuaries in Great Britain , 1991 .

[9]  R. Bunce,et al.  Changes in the abundance of farmland birds in relation to the timing of agricultural intensification in England and Wales , 2000 .

[10]  William J. Sutherland,et al.  The winter distribution of seed‐eating birds: habitat structure, seed density and seasonal depletion , 1999 .

[11]  H. Crick.  A bird-habitat coding system for use in Britain and Ireland incorporating aspects of land-management and human activity , 1992 .

[12]  A. Brown,et al.  Habitat associations of coastal wintering passerines , 1996 .

[13]  J. Gentle,et al.  Randomization and Monte Carlo Methods in Biology. , 1990 .

[14]  Joseph Chilver,et al.  The Basic Techniques , 1979 .

[15]  Jeremy D. Wilson,et al.  Field use by farmland birds in winter: an analysis of field type preferences using resampling methods , 1996 .

[16]  J. Thompson.  Mixed blessings. , 1992, Nursing times.

[17]  A. J. Morris,et al.  Use of set-aside land in winter by declining farmland bird species in the UK , 1999 .

[18]  P. Donald,et al.  Habitat use and diet of skylarks Alauda arvensis wintering on lowland farmland in southern Britain , 2001 .

[19]  K. Norris,et al.  Is the density of redshank Tringa totanus nesting on saltmarshes in Great Britain declining due to changes in grazing management , 1998 .

[20]  V. Brown,et al.  The management of lowland neutral grasslands in Britain: effects of agricultural practices on birds and their food resources , 2001 .

[21]  C. Lever.  The Atlas of Wintering Birds in Britain and Ireland Edited by Peter Lack T. and A.D. Poyser for the British Trust for Ornithology and Irish Wildbird Conservancy, 1986, 447 pp, £19·00 , 1987, Oryx.

[22]  C. Perrins,et al.  Birds of the Western Palearctic , 1978, Nature.

[23]  G. Tucker.  Effects of agricultural practices on field use by invertebrate-feeding birds in winter , 1992 .

[24]  Stephen J. Browne,et al.  Densities and population estimates of breeding Skylarks Alauda arvensis in Britain in 1997 , 2000 .

[25]  Rhys E. Green,et al.  FACTORS AFFECTING THE DIET OF FARMLAND SKYLARKS, ALA UDA ARVENSIS , 1978 .

[26]  J. Kirby,et al.  Spatial dynamics of wintering Lapwings and Golden Plovers in Britain and Ireland, 1981/82 to 1983/84 , 1993 .