Spanning the habitat gradient: Red-headed woodpecker nest-site selection in three distinct cover types

Abstract

Understanding species habitat relationships is fundamental to ecology and underpins conservation-based management. Species with broad habitat preferences and wide geographic ranges are capable of fulfilling breeding requirements in different habitat contexts. Habitat selection in these species may vary in a context-specific way, so determining the factors driving habitat selection requires spanning the habitat gradient. Complex landscapes offer a unique opportunity to compare habitat selection across habitat gradients within a single study site. Here, we used a comparative approach to model scale-dependent nest-site selection of the red-headed woodpecker (Melanerpes erythrocephalus) in three distinct cover types at Fort A.P. Hill military installation, Virginia. We found that nest preferences varied among cover types for several patch-scale habitat features. In closed forests, red-headed woodpeckers selected patches with an open canopy characteristic that lacked holly (Ilex opaca) in the understory and contained large pines. In open forests, patches with a high percentage of canopy cover were also avoided. In wetlands, patches with low percent stem cover were preferred. We also found a single variable, medium/large snag density, was highly influential in models for all cover types at the patch scale, indicating the importance of suitable snags for nesting, irrespective of cover type. Models at the tree scale showed similar results for all cover types: red-headed woodpeckers consistently preferred large snags with less bark. Our results demonstrate the value of comparing habitat selection across a habitat gradient. Managers charged with promoting red-headed woodpecker populations would do well to manage for large, partially decayed snags while also considering context-specific habitat needs.