Conservation value of pome fruit orchards for overwintering birds in southeastern France

Abstract

Bird survival in winter relies on the availability of key population resources such as food, shelter and resting sites. In annual crops, intensive crop management has been shown to affect bird communities through a reduction in winter resources, but much less is known about perennial crops. In this study, we performed bird surveys in 30 orchards for two years to investigate how abundance, species richness and evenness in wintering bird communities were affected by the availability of unharvested fruits in pome fruit orchards and of fruiting ivy in surrounding hedgerows. We further investigated how these resources depend on orchard management. We observed 41 bird species overall, among which 13 were of conservation concern. Bird abundance was mainly driven by the number of unharvested fruits and to a lesser extent by the number of ivy bearing trees. Bird species richness was primarily driven by the number of ivy bearing trees. This result was consistent with analyses at the species level, indicating that the occurrence of seven species (Sylvia atricapilla, Parus caeruleus, Parus major, Erithacus rubecula, Turdus iliacus, Turdus merula, and Turdus philomelos) was significantly dependent on the number of ivy-bearing trees. Interestingly, compared to organic orchards, non-organic (conventional and integrated) orchards had significantly more unharvested apples because of the absence of prophylactic measures against pests, thus providing wintering birds with more available resources. Our study supports the conservation value of commercial pome fruit orchards for Palearctic bird species overwintering in Southern Europe.