Influence of autumn applied herbicides on summer and autumn food available to birds in winter wheat fields in southern England

Herbicides applied to control problem weed species can directly reduce the availability of non-target plant species and, indirectly, invertebrates important as food for birds. Therefore, the effects of an autumn herbicide application on the flora and invertebrate fauna were studied within the field headland of winter wheat (Triticum aestivum L.) crops over three years. Replicated plots were either treated with a herbicide or left untreated. Floral percentage cover and diversity were assessed in quadrats on two dates, and invertebrates sampled using a vacuum sampler on five dates, between May and July each year. A significantly greater floral cover (p < 0.001), species diversity (p < 0.001) and higher numbers of many arthropod groups, such as Heteroptera (p < 0.001), Auchenorrhyncha (p < 0.001) and Coleoptera (p < 0.001), important in the diet of farmland birds, were found on all untreated plots. Selective pesticide use is suggested as a method that could help reverse the decline found in many species of farmland bird, by improving the availability of weed and invertebrate food in an intensively farmed landscape. (C) 1999 Elsevier Science B.V. All rights reserved.