Northern Goshawk (Accipiter gentilis)
The Northern Goshawk was heavily persecuted in the early 20th Century, primarily because it was perceived as a villainous predator of highly valued game species. With the passage of protective legislation, most notably the amendment of the Migratory Bird Treaty Act to include raptors in 1972, shooting ceased to be a major source of mortality. The goshawk depends entirely on extensive stands of mature, old-growth forests. Unfortunately as mature and old growth forests become more and more rare, so do goshawks. Numerous scientific studies have documented lower or declining goshawk populations in heavily logged forests. As logging pressures have increased, the goshawk has experienced population declines as a result of severe habitat loss and degradation. Additionally, the noise and disruption caused by intense industrial logging operations such as road building, heavy machinery operations, and logging truck traffic, have caused nest failure, especially during pair bonding, nest-building and incubation. While logging is the primary threat to goshawks, other activities also threaten the long-term health of the species in the Sierra Nevada. Cattle grazing, fire suppression, insect and tree disease, mining, recreation, road building and other forest disturbances can also lead to the deterioration or loss of nesting habitat.
Northern Goshawks typically nest in conifer forests containing large trees and an open understory on the west slope of the Sierra. Goshawks are most likely to be seen within forests, adroitly flying through the trees beneath the forest canopy thanks to their short, powerful wings and long rudder-like tail. Goshawks usually place their nests in the lower boughs of old growth forest trees where they feel protected against unwanted visitors and still have clear flight access into and out of the nest. They are generally intolerant of intruders near the nest and are known for their aggressive defense of the area surrounding an active nest. The Northern Goshawk is an extremely secretive and elusive woodland raptor that avoids humans and human activity.
The goshawk is an excellent indicator species of old growth forest health. Because the goshawk sits atop the food chain as a highly effective predator, its decline contributes to the unraveling of forest ecosystems, stressing other forest dependent species. If a forest is not healthy enough to support the goshawk, numerous other species will also be negatively impacted by both the lack of this ecosystem regulating predator and the general demise of forest health and integrity. As the builders of numerous, large nests, goshawks provide essential nesting opportunities for many species which can not build their own nests. Each breeding pair of goshawks build and maintain between three and nine nests within their home range, but use and defend only one per year. This leaves numerous nests for other species to utilize to ensure their own survival. In short, ensuring that old growth forests throughout the Sierra Nevada are protected from logging and other degrading activities will go a long way toward safeguarding Northern goshawks.
The Northern goshawk is listed by the California Board of Forestry as a sensitive species in the California Forest Practice Rules, and is currently listed as a sensitive species by the US Forest Service. The California Department of Fish and Game listed the northern goshawk as a third priority “Species of Special Concern” in 1978.
In 1991, the Center for Biological Diversity first petitioned the U.S. Fish & Wildlife Service to list all goshawks in the western U.S. as endangered. Because of the tremendous blow this would deliver to the timber industry, by calling for the protection of old growth forests, the agency twice turned the petition down. Both times, however, the Center took them to court and won, prompting a federal judge to note that “the agency seems to have a policy against listing species as endangered if they live in trees valued by the timber industry.” In 1998 the Northern Goshawk was once again denied listing by the U.S. Fish and Wildlife Service stating that no evidence was found showing a decline in the goshawk populations of the western United States.
Block, W.M., M.L. Morrison, and M.H. Reiser.1993. The Northern Goshawk: Ecology and Management. Proceedings of a Symposium of the Cooper Ornithological Society Sacramento, California, 1993. Studies in Avian Biology No. 16, a Publication of the Cooper Ornithological Society. (11MB PDF)
Bloxton Jr., T.D. 2002. Prey Abundance, Space Use, Demography, and Foraging Habitat of Northern Goshawks in Western Washington. Masters Degree Thesis, University of Washington. Seattle, Washinton. (236KB PDF)
Greenwald, D.N., D.C. Crocker-Bedford, L. Broberg, K.F. Sucking, and T. Tibbitts. 2005. A Review of Northern Goshawk Habitat Selection in the Home Range and Implications for Management in the Western United States. Wildlife Society Bulletin 33(1) 120-129. (2.8MB PDF)
Weber, T.T. 2006. Northern Goshawk (Accipiter Gentilis) Nesting Habitat in Northwestern California. An Examination of Three Spatial Scales: The Nest Area, the Post-Fledging Area, and the Home Range. Masters Degree Thesis, Humboldt State University. Arcata California. (217KB PDF)
California Department of Fish and Game Natural History Information (URL) --This California state website contains rather limited and old information but is a good basic background composite for the species. Choose from a drop-down list to select the animal you are interested in.