Influence of landscape and land-use on the distribution of breeding birds in farmland in eastern England

Abstract

The relationships between landscape, land-use and the number of territories of eight species of birds, most with declining populations, were studied over 3 years in an area of largely arable agriculture in eastern England. Two species, skylark Alauda arvensis and yellow wagtail Motacilla flava, established territories within crops. More than half of skylark territories were in autumn-sown cereals, but densities were higher in set-aside and spring-sown crops, while a conservation grassland cut for hay in late July held the highest density. Skylarks did not switch territories in winter cereals for other crops as the breeding season progressed. Weak preferences were found for spring-sown crops and weak avoidance of autumn-sown crops (i.e. there were fewer territories than expected from the area under autumn-sown crops). Skylarks showed preferences for set-aside and conservation grassland but other grassland was avoided. Skylark numbers were negatively associated with hedgerow length within tetrads. Most yellow wagtails nested in spring-sown crops, especially potatoes, for which there was a strong preference; most territories were in the largest fields. More than 75% of territories of turtle dove Streptopelia turtur were associated with residential areas, scrub and woodland, with hedges used much less often than expected from their occurrence. Grass was a strongly preferred land-use. Linnets Carduelis cannabina were mainly located in small areas of scrub and there was an association with winter oil-seed rape. Common whitethroats Sylvia communis showed preferences for hedges, especially for tall hedges, though many territories were situated in field boundaries with only scattered shrubs. Lesser whitethroats S. curruca preferred only tall hedges. Both species had more territories adjacent to grass than expected, with common whitethroat also showing a preference for winter oil-seed rape. Yellowhammers Emberiza citrinella declined over the 3 years of the study. Territories were strongly associated with tall hedges, but preferences for crops were weak. The small number of reed bunting E. schoeniclus territories were almost all by water, with a preference for adjacent grass. Possible mechanisms for reversing the downward trends of bird populations on farmland are discussed.