Masters Thesis

Habitat selection by red-breasted sapsucker (Sphyrapicus ruber) in southeast Alaska old-growth forest

Conservation of a keystone species requires knowledge of habitat use across the species’ range. The factors that influence habitat selection by Red-breasted Sapsucker (Sphyrapicus ruber) in the temperate rainforests of southeast Alaska are poorly understood. I examined habitat selection of this keystone species during the breeding season in 2008 and 2009. I quantified the structural characteristics of sapwell trees and compared them to trees without sapwells, and I located nests to describe nest trees and compare characteristics of used and available nest trees and nest sites using model selection techniques. Sapsuckers selected trees for building sapwells that were intermediate in size, had high bark furrow depth, and had a greater incidence of conks and dwarf mistletoe. Nesting Sapsuckers did not show bias for cavity orientation and nest trees were predicted primarily by size and the presence of fungal infection at intermediate stages of decay. Nest sites contained a lower volume of trees, higher DBH, increased incidence of fungal infection, and older decay classes of coarse woody debris than available sites. These findings suggest that during the breeding season, Red-breasted Sapsuckers select habitats with attributes characteristic of the full range of old-growth forest succession, and they therefore may need substantial forest structural diversity for their feeding and nesting activities. The results from this study provide information that can be used to identify habitat for breeding and foraging Red-breasted Sapsuckers. Due to their status as a keystone species, maintaining adequate breeding habitat in southeast Alaska is important not only to the local population of Red-breasted Sapsuckers, but for other species as well.

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