Abstract
The presence of rotted wood is often noted in descriptions of woodpecker nest and roost sites, and ornithologists have found that certain fungi and species of woodpeckers, such as the red heart fungus (Phellinus pini) and Red-cockaded Woodpeckers (Picoides borealis) are intimately linked. The relationship assumed is usually one of woodpecker dependence or preference for partially decayed wood in which to excavate cavities, but the woodpecker is also sometimes suggested as a vector for the fungus. In this paper we review such associations and describe patterns evident among woodpecker nest sites that suggest microclimatic and microhabitat characteristics favoring fungal colonization of trees, woodpecker-favorable responses of trees to fungi, and ultimate use of the trees for woodpecker cavity excavation. Factors that favor fungal invasion and tree use by woodpeckers include tree species, growth history, site characteristics such as proximity to water and exposure to sun or shade, nature and position of tree injury, local climate, forest age and species composition, fire frequency, and human management activities. Woodpecker cavity height and entrance orientation may be related to the dispersal dynamics of fungi, which in turn may be related to forest vegetation, thermal, and hydric characteristics.