Red-headed Woodpecker Habitat Selection and Breeding Ecology on Fort Drum Military Installation, New York
Date of Graduation
John W. Edwards
Jeffrey S. Bolsinger
Todd E. Katzner.
Red-headed woodpecker (Melanerpes erythrocephalus) populations have declined range-wide over the past 40 years, although the causal mechanisms implicated in the observed declines remain poorly understood. Population decline has been most severe at the periphery of their range, particularly in the northeastern United States, coinciding with a region where there is little information regarding red-headed woodpecker habitat use or demography. A detailed knowledge of habitat requirements and population dynamics is prerequisite for the effective conservation and management of imperiled wildlife populations, and this knowledge gap likely precludes informed management decisions for red-headed woodpeckers in the northeastern portion of their range. In response to the extreme paucity of information regarding red-headed woodpecker habitat selection and breeding ecology in the northeastern United States, I conducted a field study on Fort Drum Military Installation, New York where a small but regionally important population of 10--15 adult red-headed woodpecker pairs regularly breeds. From May to August 2012--2013 I surveyed the installation for red-headed woodpecker breeding territories and located 15 and 11 territorial pairs in 2012 and 2013, respectively. I subsequently located nest cavities of breeding pairs to monitor reproductive success and conducted extensive habitat sampling to assess nest-habitat selection.;I used boosted regression trees (BRT) to identify red-headed woodpecker nest-habitat thresholds at multiple spatial scales. Red-headed woodpeckers exhibited nest-tree thresholds related to tree (1) decay class, (2) dead-limb length, and (3) diameter at breast height (dbh), while forest patch (i.e., surrounding vegetation) thresholds were related to (1) total dead-limb length, (2) understory height, (3) average tree dbh, and (4) large tree (≥30-cm dbh) density. These results provide objective criteria for managing nesting habitat for red-headed woodpeckers, and indicate the relative importance of nest-tree and forest-patch characteristics on nest-site selection.;I modeled red-headed woodpecker daily nest survival rates (DSR) as a function of temporal and habitat-specific covariates using logistic-exposure models to identify factors influencing nest survival and better understand the underlying mechanisms affecting reproductive success and productivity. A total of 30 red-headed woodpecker nesting attempts by 22 breeding pairs were monitored over the course of the study and I documented low rates of reproductive success (overall nest success = 32%) and observed high rates (>80%) of nest predation. DSR was most influenced by cavity concealment, such that nests with greater vegetative structure surrounding (within 1 m 2 of) the nest cavity had higher survival rates--an attribute that likely reduced nest predation.;I also sought to identify factors influencing large-scale selection of breeding habitats by red-headed woodpeckers, and used BRTs to compare characteristics (structure and composition) of forest stands occupied and unoccupied by breeding territories. Red-headed woodpeckers selected forest stands with greater overall stand decadence (decay) and shorter woody understory height. My results suggest that at coarse spatial scales (i.e., forest stands or habitat fragments) red-headed woodpecker selection of breeding habitats can be influenced by overall stand decadence and management strategies that recruit numerous decadent trees into forest stands will increase available habitat for this species. This study provides resource managers with meaningful estimates of red-headed woodpecker resource selection and reproductive success that can be used as guidelines to conserve habitat for this species.
Berl, Jacob L., "Red-headed Woodpecker Habitat Selection and Breeding Ecology on Fort Drum Military Installation, New York" (2013). Graduate Theses, Dissertations, and Problem Reports. 10.