Effects of Habitat on Breeding Success in a Declining Migrant Songbird: the Case of Pied Flycatcher Ficedula Hypoleuca

Habitat is a key determinant of breeding success in hole-nesting birds. Identifying the factors that influence breeding success is important in understanding nest-site selection behaviour and devising appropriate conservation strategies. This is especially true for declining species like the migratory Pied Flycatcher Ficedula hypoleuca. Here, I analyse the effect of 24 habitat variables on clutch size, hatching success and fledging success for 137 Pied Flycatcher nests in Gloucestershire, UK, using volunteer-collected data from a 5-year period. More successful nests tended to be located in areas with a lower density of mature trees but abundant saplings. Tree and sapling species richness was also important. Success was positively related to abundance of Oak Quercus robur and Silver Birch Betula pendula and negatively related to Beech Fagus sylvatica, Sycamore Acer pseudoplatanus and Bracken Pteridium aquilinum. Success was lower in boxes facing south-southwest and higher in boxes located on sorter trees. Despite Pied Flycatchers often being regarded as birds of grazed (open) woodland, success was not related directly to grazing. Close proximity to footpaths was associated with significantly lower clutch size, numbers of young to fledge, and percentage success, while close proximity to water was associated with increased success at all stages of breeding. This is a single-site study and the generality of these findings at other sites cannot be assumed without empirical testing. However, the results provide useful additional insight into success-habitat interactions in this species that, to some extent, challenge the general view of Pied Flycatchers, in the UK at least, as grazed woodland specialists