Seasonal Habitat Use by Sitka Black-Tailed Deer on Admiralty Island, Alaska

Abstract

We measured seasonal habitat use by 30 radio-collared Sitka black-tailed deer (Odocoileus hemionus sitkensis) on northern Admiralty Island in southeastern Alaska from February 1979 to July 1982. Habitat use varied seasonally as deer moved from low-elevation ( 600 m) summer ranges in open canopy subalpine and alpine habitats. Deer used oldgrowth forest almost exclusively during winter and spring, and high-volume old growth (>74 mbf/ha) was used in much greater proportion than its abundance. To minimize the impacts of timber harvesting on deer populations, emphasis should be placed on maintaining stands of high-volume old growth on low-elevation deer winter ranges. J. WILDL. MANAGE. 54(3):371-378 The Sitka black-tailed deer in southeastern Alaska occurs at the northern limit of its natural range (Wallmo 1981). This subspecies inhabits a densely forested coastal environment where deep winter snows are the major factor limiting population size (Klein and Olson 1960). In high snowfall regions of the Pacific Northwest and in southeastern Alaska, low-elevation old-growth forest has been identified as essential deer winter range (Bloom 1978, Wallmo and Schoen 1980, Bunnell and Jones 1984). The 6.8 million-ha Tongass National Forest encompasses over 80% of the land area of southeastern Alaska. Approximately 7,000 ha of old growth on National Forest lands, as well as additional thousands on state and private lands, are scheduled for harvest annually (U.S. For. Serv. [USFS] 1988). Converting old-growth forests to younger seral forests in Alaska will reduce forage availability and consequently deer carrying capacity (Wallmo and Schoen 1980, Alaback 1982). In southeastern Alaska, the old-growth forest is variable in structure and composition on a fine-grained (<1 ha) scale (Schoen et al. 1984). Timber harvesting in this region has been concentrated in the most economically valuable oldgrowth stands, specifically on low-elevation, high-volume sites (Hutchison and LaBau 1975, Schoen et al. 1988). An understanding of the seasonal habitat use of deer, including their use within the forest mosaic, will help managers identify important habitats and guide modeling efforts aimed at predicting the effects of timber harvesting on deer populations in southeastern Alaska. We assume that current habitat preferences are indicative of long-term habitat requirements or needs (Fagen 1988, Ruggiero et al. 1988). Our objectives were to determine seasonal habitat use of radio-collared deer and to describe the implications of harvesting timber on deer populations in southeastern Alaska. Our project was supported by the Alaska Department of Fish and Game through Federal Aid in Wildlife Restoration Project W-17, W-21, and W-22, and the U.S. Forest Service, Pacific Northwest Forest and Range Experiment Station. We recognize the late O. C. Wallmo for his cooperation, advice, and encouragement during the initial stages of this study; G. G. Fisch, L. R. Beier, L. H. Holton, L. J. Johnson, and J. W. Lentfer for their assistance during this study; and D. A. Anderson, R. W. Flynn, L. M. McManus, and W. L. Regelin for reviewing this manuscript. D. R. McCullough and an anonymous reviewer offered valuable editorial suggestions.