Summer bird abundance and distribution on set‐aside fields on intensive arable farms in England

The abundance and distribution of breeding birds were compared on paired fields comprising one set‐aside field and one crop field, on 11 intensive arable farms in eastern and western England. A single observer made four visits to all set‐aside and crop fields between April and July and recorded all birds seen during standardised counts and transects. Rotational and non‐rotational set‐aside supported higher densities and more species of birds than fields of wheat, brassicas, root crops and seed rye. These differences in density, between set‐aside and crops, were evident across a suit of species including waders, gamebirds, pigeons and passerines and were particularly marked on rotational set‐aside. The majority of species recorded in fields away from boundaries would have been feeding rather than nesting there and higher bird densities on set‐aside compared with adjacent arable crops probably reflects greater food abundance in the former. The study is the first to demonstrate a clear habitat preference for set‐aside by a wide range of bird species throughout the breeding season and it allows a number of recommendations to be made concerning the development of cost‐effective agri‐environment measures. The fact that the majority of birds utilised the outer 5 m, or in some cases 20 m, margin of the field suggests that many of the benefits of whole field set‐aside may be derived from marginal strips. A slight, but not significant preference for rotational over non‐rotational set‐aside suggest such margins should be managed to maintain a patchy, relatively diverse sward of arable plants. A key feature of set‐aside is the scale at which it has been incorporated into the arable landscape. Agri‐enviromental schemes will only provide similar national benefits if they are implemented on a wide scale in such as way as to promote high uptake by farmers.