Hairy woodpecker winter ecology in ponderosa pine forests representing different ages since wildfire

We investigated how changes in vegetation structure and prey resources following wildfire affected the winter ecology of hairy woodpeckers (Picoides villosus) in ponderosa pine (Pinus ponderosa) forests of northern Arizona, USA. Using point-counts, radiotelemetry, and focal bird observation, we assessed the relative abundance, home range size and composition, and habitat use by foraging hairy woodpeckers in 3 stands that had experienced wildfire in 1996, 2000, or 2002. Because we conducted the study over 2 years, we used the 1996 fire to represent 6 and 7 years after fire, while we used the 2000 fire to represent 2 and 3 years after fire in a space-for-time substitution chronosequence analysis. We also assessed bark beetle and woodborer density by x-raying bark samples collected from a subset of trees within burned areas. We detected significantly greater hairy woodpecker relative abundance in burned forests representing 1 and 2 years after fire, and bark beetle and woodborer density was highest in these stands as well. Woodpecker home range size increased across stands representing increasing time since fire. Within a burn, hairy woodpeckers used high-severity burned areas more than moderate-severity burned areas representing 2 and 3 years after fire, but not in areas representing 6 and 7 years after fire. Bark beetle and woodborer densities were also higher in high-severity burned stands representing 2 and 3 years after fire. Hairy woodpeckers used edges of high-severity burned areas more than the interior. We hypothesize that an initial increase in bark beetle and woodborer density following fire allowed for higher woodpecker abundance and smaller home ranges, but as burned forests aged, bark beetle and woodborer density within trees decreased, killed trees fell, and, in response, hairy woodpecker relative abundance decreased and home range size increased. These patterns suggest that high-severity burned areas provide important but ephemeral resources to this dominant primary cavity-nester. The higher bark beetle and woodborer densities and greater use of edges of high-severity burned areas by woodpeckers suggests that salvage logging of these areas could remove potential prey and preferred foraging areas for hairy woodpeckers, especially when trees are removed along severely burned edges.