Conservation assessment for the northern goshawk in southeast Alaska.

Iverson, George C. ; Hayward, Gregory D. ; Titus, Kimberly; DeGayner, Eugene; Lowell, Richard E. ; Crocker-Bedford, D. Coleman; Schempf, Philip F. ; Lindell, John. 1996. Conservation assessment for the northern goshawk in southeast Alaska. Gen. Tech. Rep. PNW-GTR-387. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 101 p. (Shaw, Charles G., III, tech. coord.; Conservation and resource assessments for the Tongass land management plan revision). The conservation status of northern goshawks in southeast Alaska is examined through developing an understanding of goshawk ecology in relation to past, present, and potential future habitat conditions in the region under the current Tongass land management plan. Forest ecosystem dynamics are described, and a history of forest and goshawk management in the Tongass National Forest is reviewed. Nearly 900,000 acres of the most productive old-growth temperate rain forest in southeast Alaska (public and private lands) have been harvested during the past 90 years and changed to early seral conifer forests. Goshawk habitat relations are described through a review of the goshawk literature. Significant preliminary findings of a habitat relation study in southeast Alaska include the following: goshawks select productive old-growth forests with > 60 percent of all adult goshawk telemetry relocations occurring in this cover type; nonforest, clearcut, and alpine cover types were least used and were avoided relative to their availability; and the median breeding season minimum convex polygon use areas of adult goshawks was about 10,000 acres. Goshawks predominantly use gentle slopes (70 percent of relocations) at elevations below 800 feet (54-74 percent of relocations); 24 percent of relocations occurred in riparian habitat zones, and nearly 20 percent of all relocations occurred within the beach fringe habitat extending 1,000 feet inland from the ocean shoreline. Goshawk nesting habitat is a nonrandom subset of the landscape with a significantly higher proportion of productive old-growth forest within a 600-acre analysis area surrounding known nests. The probability of persistence of goshawks has declined over the past 50 years owing to habitat loss and likely will continue to decline under current management plan regimes; however, the goshawk population likely is not in immediate peril. The predicted consequences of several alternative habitat management approaches are compared. This analysis suggests that long rotation forestry (e.g., 300 years) and uneven-aged silvicultural management may maintain habitat characteristics important to sustaining goshawk populations well distributed across the region. Although habitat reserves are not considered an essential component of a forest-wide goshawk conservation strategy, reserves, in combination with extended rotations, may be important where the intensity of past management actions has precluded the opportunity to attain a desired combination of forest age classes achieveable under long rotations. Reserves are most likely critical if extensive clearcut logging continues.