Agricultural habitat-type and the breeding performance of granivorous farmland birds in Britain

Conservation concern about granivorous birds has led to the implication of changing agricultural practices as causes of widespread population decline. We investigate relationships between breeding performance and the agricult ural environment for ten granivorous farmland bird species (Stock Dove Colu mba oenas, Skylark Alauda arvensis, Trec Sparrow Passer montanus, Chaffinch Fringilla coelebs, Greenfinch Carduelis chloris, Linnet C. cannabina, Bull finch Pyrrhula pyrrhula, Reed Bunting Emberiza schoeniclus, Yellowhammer E. citrinella and Corn Bunting Miliaria calandra). We analyse long-term, exte nsive data from the British Trust of Ornithology's Nest Record Scheme on br eeding performance per breeding attempt with respect to farmland type (arab le, grazing or mixed) and time (pre- and post-1975-76). The influence of ha bitat is investigated at two different scales: within the nesting territory and at the landscape level. Relationships between farmland type and (tempo ral changes in) breeding performance tended to be species-specific, but a f ew patterns were each common to some species. Improvements in breeding perf ormance occurred across all three farmland types for four declining species . Grazing farmland seems to have deteriorated as breeding habitat for Linne t and arable/mixed farmland for Reed Bunting. Mixed farming at the territor y scale supported better breeding performance for four species, three of wh ich (Bullfinch, Yellowhammer and Corn Bunting) have declined concurrently w ith mixed farming. Pastoral landscapes supported better breeding performanc e for up to seven species, six of which have undergone large declines. Arab le landscapes supported better breeding only for the stable or increasing C haffinch and Greenfinch. Different relationships between farming regime and breeding performance were found at the two scales considered.