Effect of Forest Vegetation on Nest-Site Selection by Spruce Grouse Across Two Spatial Scales

The spruce grouse (Falcipennis canadensis) is a gallinaceous bird that is threatened or endangered throughout much of the southeastern limit of its range. Generally associated with short-needled conifer forests like those characteristic of northern Maine, this species may be particularly sensitive to recent changes in timber harvesting practices. I examined nest-site selection to better understand spruce grouse habitat associations in northern Maine. In the summer of 2013, I located the nests of 12 female spruce grouse in commercially-managed forests of north-central Maine. I measured vegetation characteristics at nests and at sampling points 30 meters from nests, as well as points randomly distributed throughout the stand where a nest was located. I examined differences in characteristics at sites used for nesting and sites available across within-patch and patch-scales. Logistic regression revealed that at within-patch scale, sites with higher lateral cover were selected for nesting. At the patch-scale, lower tree density and lower basal area of live trees, but higher lateral cover and greater recess height were associated with sites selected for nesting. These scale-dependent differences suggest that high concealment is selected by nesting hens, but that small forest-gap structure is also selected for by hens in the stand surrounding their nest. My results indicate that nesting spruce grouse select for gaps within dense forest structure which provide a combination of nest-level lateral cover, overhead canopy cover, and nearby trees for escape cover by adults