Chaffinch (Fringilla coelebs) Science Article 3
abstract
Numbers of many bird species which breed on farmland, and are reliant oncropped land for feeding or nesting, declined between the 1960s and 1990s. Incontrast, Chaffinch Fringilla coelebs numbers increased on farmland over thesame period. This study investigates the influence of both cropped and noncroppedland on Chaffinches foraging for nestlings, nestling survival andterritory density. The study was carried out on nine mixed lowland farms insouth central England in 1996 and 1997. Chaffinches made little use of croppedareas when foraging for young (less than 9% of foraging visits, despite croppedareas covering 93% of study areas). Instead, trees and bushes influencedforaging patterns and breeding success. Extensive use was made of trees andbushes by adults searching for food for nestlings (75% of foraging visits wereto hedges and trees within boundaries or fields, despite these areas covering<3% of study areas). Oaks (69% of visits) and Willows (15% of visits) werefound to be the most favoured species of tree for foraging. In one year of thestudy, chick starvation was less frequent in nests located on field boundarieswith Oak trees than in nests on boundaries without Oaks. Successful nests alsotended to be closer to Oak or Willow trees than those where nestlings starved.Territory density was not related to hedgerow structure, presence or absence ofOaks and Willows in field boundaries, or adjacent cropping. Our findings onnest survival were supported by analysis of British Trust for Ornithology nestrecord data which revealed that nests associated with trees had better broodsurvival rates than sites not located close to trees. The use of trees and shrubsfor feeding and nesting in the farming landscape and the ability to utilizeunkempt hedgerows may have contributed to the ability of Chaffinches topersist on farmland despite wide-scale agricultural change in recent decades.
Mark J. Whittingham, Richard B. Bradbury, Jeremy D. Wilson, Bird Study (2001) 48, 257-270