Pileated Woodpecker Occupancy and the Occurrence and Recruitment of Key Habitat Attributes in a Managed Forest
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University of Washington Abstract Pileated Woodpecker Occupancy and the Occurrence and Recruitment of Key Habitat Attributes in a Managed Forest Amber Mount Chair of Supervisory Committee: PhD John M. Marzluff School of Environmental and Forest Sciences As anthropogenic land use accelerates, it is critical that resource managers evaluate and address the needs of wildlife species. Managed forests have a unique opportunity to provide economic stability in communities while maintaining habitat for forest associated species. Forest management prescriptions include leaving areas of undisturbed mature trees to provide habitat for wildlife. It is essential, yet not often done, to both evaluate the habitat that is left as well as monitor the species that are meant to benefit from this habitat. My thesis aims to fill this gap on a private forest in Western Washington by assessing the occurrence and recruitment of standing dead trees (snags) and a species dependent upon this resource, the pileated woodpecker (Dryocopus pileatus). I estimated the density of snags across Green Diamond Resource Company’s (GDRCo) Olympic Tree Farm that operates under a Habitat Conservation Plan (HCP). The HCP has a requirement to retain 4.9 snags per hectare (SPH) >61 cm Diameter at Breast Height (DBH) and 4.9 SPH 30-61 cm DBH to provide habitat for cavity nesting birds. The purpose of this study was to examine if the goals are currently being met and if the forest is on a trajectory to meet those goals throughout the life of the HCP (50 years). I found that the goals for small snags are being met and the goals for large snags are not being met. Net recruitment of snags for both size classes was positive. If these recruitment rates remain the same, snags will increase over time and the goal for large snags will be reached in fifteen years, at year 30 of the HCP. I also surveyed for pileated woodpeckers on the managed tree farm and modeled its detection and occupancy using PRESENCE (http://www.mbr-pwrc.usgs.gov/software/presenece.html). I estimated that woodpeckers occupied 27.5% of survey locations, which is surprising for a species initially thought to be an obligate of expansive mature forests. The models that performed best included the amount of forest aged 30-45 within 277ha of a survey location, which was negatively correlated with occupancy and the amount of mature forest within 277ha, which was positively correlated with occupancy. With a one percent increase in forest aged 30-45 within the 277ha home range, I found a 10.25% decrease in the likelihood of a site being occupied by pileated woodpeckers. With a one percent increase in mature forest in the 277 ha home range, I found a 3.68% increase in the chance of the site being occupied by pileated woodpeckers. My findings suggest that mature forest reserves are necessary for maintaining pileated woodpecker habitat. Mature forest reserves will become increasingly important as intensively managed forests move to a younger rotation age.
- Forestry