, /-I bl 9 INSECTS ON FARMLAND AND THEIR IMPORTANCE TO GRANIVOROUS BIRDS

Many species of farmland birds have shown huge declines in numbers and range since the 1970s due to agricultural intensification, and these declines have been worst amongst granivorous species. Recent studies have suggested that low abundance of invertebrate chick food may have been important in driving the declines of a number of granivorous species, however causation has still only been proved for the Grey Partridge, whose decline has been attributed to low chick survival due to the indirect effects of herbicides reducing invertebrate abundance. We investigated invertebrate declines and how they may have affected farmland bird populations in a number of ways. There is little long-term data on abundance of farmland invertebrates. Thus we first looked at how representative data from a long-running suction trap was of invertebrate abundance on local farmland. Suction trap catches reflected abundance of aerial invertebrates on local farmland, and also to abundance of epigeal invertebrates in many cases, particularly abundances in predominant crop types. Secondly, we looked at spatial and temporal distribution of invertebrates on farmland in order t