White-headed Woodpecker (Picoides albolarvatus) habitat selection and nest survival: a multi-scale analysis

We located and monitored nests of white-headed woodpeckers (Picoides albolarvatus) in the Sierra Nevada, California, and collected data on habitat at nest sites and random sites at three spatial scales. Our goal was to identify variables important to habitat selection and for nest survival, and to determine if habitat selected by white-headed woodpeckers was consistent with habitat that resulted in higher nest survival. Habitat selection models at the nest-site and 125-ha scales best predicted White-headed Woodpecker nest occurrence. Models for nest survival generally had poor predictive power. White-headed Woodpeckers nested on south-facing slopes and at higher elevations compared to random plots. Nest survival increased with warmer maximum temperatures, at higher elevations, and on north-facing slopes. At the nest site scale, White-headed Woodpeckers nested in areas with open canopy, high basal area of snags, and in more decayed substrates while no variables were important for nest survival at this scale. At the 1-ha scale, White-headed Woodpeckers nested in areas with higher basal area of conifers and lower density of snags while no variables were important for nest survival. At the 125-ha scale, models for habitat selection and nest survival were in agreement. Nests were found in areas of higher canopy cover of conifers and edge density and were more successful under these conditions. Our results suggest that white-headed Woodpeckers select heterogeneous landscapes when viewed across multiple scales: they selected sites with low canopy cover at nest sites within a forest of moderate canopy cover.