Influence of nesting habitat on breeding Song Thrushes Turdus philomelos

摘要

Capsule Habitat significantly influences nest-site choice, breeding output and daily nest failure rates in Song Thrushes. Aims To describe nesting habitat of a stable Song Thrush breeding population, investigate habitat influence on breeding, and examine what variables influence nest-site selection by comparing habitat variables in nesting sites with random non-nesting sites. Methods Nesting habitat data were collected throughout Ireland in 2001-03 during a detailed study in County Cork and by volunteers across the country. Results Most nests were located 1.3-2.4 m from the ground. Nests built in April were significantly higher than those built in May. Nest-sites were mostly in trees, bushes or hedgerows and we highlight the role of garden habitat for nesting. Clutch size was significantly higher (mean plus or minus sd) on farmland (4.5 plus or minus 0.7) than in garden and parkland (4.0 plus or minus 0.5) and woodland (4.0 plus or minus 0.6). The number of hatched chicks was significantly greater in hedgerows (4.1 plus or minus 0.9) than in trees (3.2 plus or minus 0.7), but not in bushes (3.7 plus or minus 0.9), while the number of fledged chicks was significantly lower in nests in trees (3.2 plus or minus 0.7) than in hedgerows (4.2 plus or minus 0.8) and bushes (3.8 plus or minus 0.7). Daily nest failure rates were significantly lower for nests in trees and partly concealed nests across different nest periods. Nesting sites had significantly denser vegetation than non-nesting sites. Conclusion Dense vegetation is an important deciding factor for Song Thrushes when choosing a nest-site and may be an important consideration in conservation measures striving to maintain or restore Song Thrush populations.