Causes of nest failure among buntings in the UK

Causes of nest failure among the four lowland buntings in the UK, Yellowhammer, Cirl Bunting, Reed Bunting and Corn Bunting, were investigated using records from 1924-92 held by the BTO's Nest Record Scheme.Three main types of failure were identified: nest-predation, destruction by agricultural operations (e.g.crop harvesting, cattle trampling, hedge cutting) and natural causes (e.g.rain, adult predated).Nest predation accounted for a third of nests of Yellowhammer, Cirl Bunting and Reed Bunting but was less important for Corn Bunting.Nest predation was more prevalent during the nestling stage than egg stage, and failure due to agricultural operations occurred more during the egg stage than nestling stage for Yellowhammer and Reed Bunting.Many farmland species have shown population declines since 1970, coinciding with changes in predator populations, farming practices and possibly weather patterns, and the relative importance of each cause in pre-and post-1970 samples was therefore compared.Corn Bunting showed an increase in the relative importance of losses due to farming processes between the two periods from 10% to 43% of reported failures, representing an approximate increase in the proportion of nests affected from 7% to 21%, although the overall failure rate was lower in the post-1970 sample.Causes of nest failure were essentially unchanged for Yellowhammer and Reed Bunting.No such comparison was possible for Cirl Bunting due to a paucity of early records.