Habitat relationships of spruce grouse in southeast Alaska
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Abstract
A geographically disjunct subspecies of spruce grouse, the Prince of Wales spruce grouse (Falcipennis canadensis isleibi), occurs on only a few islands in southeast Alaska. Other than limited morphology data, the scientific literature lacked any information on habitat relationships, ecology, and natural history of this subspecies. Moreover, no field studies had been conducted on spruce grouse in a temperate rainforest ecosystem. Thus, habitat relationships could not be readily inferred from the existing literature because the temperate rainforest of southeast Alaska is disfinct from other ecosystems in the range of spruce grouse.
Spruce grouse were studied on Prince of Wales and Heceta Islands in southeast Alaska from April 1996-January 1998. Nineteen birds were captured and fitted with radio transmitters. Grouse were radio-tracked throughout the year w ith an emphasis on collecting data during the reproductive period. Habitat data were evaluated at 3 spatial scales (home range, core area, location) using logistic regression. .A logistic model was fitted at the smallest scale of resolution, individual locations. Spruce grouse selected bog and high-volume, old-growth forest habitat and avoided clearcuts. Second-growth forest (15-30 yrs after clearcutting) and scrub forest habitats were used in proportion to their availability. No grouse, however, used large areas of second-growth forest exclusively, indicating that uniform structure may not be suited to all life requisites. Horizontal diversity may be an important component of spruce grouse habitat in southeast Alaska. Forest management practices which encourage horizontal diversity, avoid large patches of uniform structure, and allow connectivity of natural patches across the landscape would be less likely to isolate populations of Prince of Wales spruce grouse.