Intra-annual variation in habitat choice by an endemic woodpecker:Implications for forest management and conservation

摘要

The Canary Islands great spotted woodpecker Dendrocopos major canariensis is an endemic bird restrictedto the Pinus canariensis forests of Tenerife and Gran Canaria. Classification tree models were applied toexplore the relationship of the occurrence of this picid and habitat variables between two contrastingperiods (breeding vs. non-breeding seasons) and for the entire annual cycle. During the reproductiveperiod the availability of mature trees (DBH > 60 cm), and snags (dead trees), for nesting and roosting,characterize the breeding territory. Outside the breeding season the choice of locations was driven bya tree cover larger than 28.5% and the presence of trees taller than 8.5 m on average, a pattern explained bythe availability of pine seeds in the cones of well-developed canopies, and less so by predation risk. Overall,during the annual cycle, well-developed canopy sites influenced the presence of this picidae (treecover > 38%) and on more open sites (<38%) the presence of mature trees (DBH> 60 cm) became thesecond most important predictor of occurrence. We suggest that food abundance and availability could bethe ultimate factor explaining the intra-annual variation observed, with the availability of snags being animportant factor during nesting. In the range of this endemic, we recommend selective cuts in pineplantations, to allow the trees to set seed and improve their crops, minimizing the elimination of snags,and killing some large pine trees if the priority is to expand the distributional range of the woodpecker.