Conservation assessment for the northern goshawk in southeast Alaska.

Abstract

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. Revision efforts for the TLMP resumed in fall 1994 with a focus on five major land management issues considered to be inadequately addressed in the existing TLMP: wildlife viability, fish and riparian habitat, caves and karst, alternatives to clearcutting, and socioeconomic considerations. Goshawk conservation is an important component within the wildlife viability issue.Concern for goshawk population viability in southeast Alaska evolved during the past decade and culminated with th...

Relating Microclimate to Epiphyte Availability: Edge Effects on Nesting Habitat Availability for the Marbled Murrelet

“…Telemetry studies of Northern Goshawks in southeast Alaska found that females were more likely to remain at low elevations below 250 m, but males, which do most of the hunting while breeding, were found at all elevations in proportion to their availability (Iverson et al 1996). There was, however, relatively little (13%) land above 600 m in this study.…”

“…Northern Goshawks frequently forage along forest edges (Squires and Reynolds 1997), but telemetry studies in southeast Alaska showed that they did not use edges more frequently than forest interior, relative to the availability of these habitats (Iverson et al 1996). Female goshawks were found within 300 m of beaches more often than expected, but males did not show this pattern.…”

“…Not unexpectedly, most murrelets were delivered early in the morning (9 between 0335 and 0511, one at 0829, and one at 2028). Iverson et al (1996) reported alcid (mostly murrelet) remains at 20% of 15 goshawk nests in southeast Alaska.…”

“…Overall, if one considers that each occurrence in a pellet represents a separate animal, for every 14 Marbled Murrelets killed there were 101 potential predators (squirrels, jays, owls) killed by goshawks. Squirrels and jays were also important prey for goshawks in southeast Alaska, and the introduction of red squirrels to some islands might have benefited goshawks there (Iverson et al 1996).…”

Within-home-range habitat selection of male Northern Goshawks in central Japan

“…(Newton 1997) (Reynolds et al 1992) (Greenwald et al 2005) (Bright- Smith & Mannan 1994, Beier & Drennan 1997, Boal et al 2005) (Widen 1989, Drennan & Beier 2003) (Iverson et al 1996) (Kenward 1982) (Rutz 2006 Fig. 1.…”