Insects as food for farmland birds - is there a problem?
The decline of farmland birds in Britain is a topical subject. Much of the discussion has been centred on the deleterious effects of ever increasing pesticide use on birds (Campbell et al., 1997; Ewald & Aebischer, 1999; Avery et al., 2003). Rather than being directly toxic, like many of the early pesticides, modern pesticides are thought to influence bird survival indirectly by affecting the availability of food items in their diet. In fact, insects have been affected by a wide variety of changes in farming practice as agriculture has become more intensive (Potts, 1997; Sotherton, 1998; Barker et al., 1999; Holland, 2003). This chapter discusses the extent to which insects figure in the diet of farmland birds, and identifies the insect groups of primary importance to birds. The evidence for declines in insect numbers in agricultural habitats will then be presented. Finally, the evidence linking these declines with reported declines in the abundance of farming birds will be considered.