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An Occasional Review of Goshawk Research and Conservation Issues

#2: Summary of Cooper and Stevens (2000) by Kierán Suckling

Cooper, J.M. and V. Stevens. 2000. A review of the ecology, management and conservation of the northern goshawk in British Columbia. British Columbia Ministry of Environment, Lands and Parks, Wildlife Bulletin No. B-101.

Much of Cooper and Stevens (2000) is a literature review of goshawk research from North America and elsewhere. This summary focuses on data relating to goshawks in British Columbia.

Twenty-eight active territories were located on Vancouver Island 1991-1997. Three active territories were located on the Queen Charlotte Islands 1995-1997.

In 1995, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) designated the northern goshawk as "not at risk" and the Queen Charlotte goshawk as "vulnerable." In 1998, the Ministry of Environment, Lands and Parks placed the Queen Charlotte goshawk (A.g. laingi) on the “red list” as a candidate for designation as “threatened” or “endangered.” A.g. laingi is ranked as “critically imperiled globally” or “imperiled globally” by the Alaska Natural Heritage Program and “imperiled” by the British Columbia Conservation Data Centre due to rarity and perceived threats to habitat. “Recent surveys (1995-1998) on Vancouver Island and the Queen Charlotte Islands of British Columbia suggest there may be less than 200 pairs of A.g. laingi in Canada which would likely warrant a Threatened COSEWIC status.”

Following a review of various population estimates, the authors conclude that “the trend seems to be inevitably downward for A.g. laingi,” though it is not known precisely to what degree.

Distribution of A.g. laingi may include the coastal mainland of British Columbia, the Olympic Peninsula, and western Oregon in addition to the more definitively established range inclusive of Southeast Alaska, the Queen Charlotte Islands, and Vancouver Island.

Preliminary telemetry data indicates winter movements to "large contiguous stands of old-growth or >60 year old second growth." On Vancouver Island, 50 percent of nest areas (14 of 28) were in contiguous old growth, five were in fragmented old growth, and nine were in second-growth forests. The second-growth forests were 40-60 years and on “good growing sites.” All three Queen Charlotte Islands nest sites were in contiguous old growth.

Home ranges are larger than in the continental United States. Nest spacing is regular. The mean inter-nest distance was 8.7 kilometers, with a minimum distance of 3.2 kilometers.

Pellet analysis on the Queen Charlotte Islands showed that red squirrels made up 44 percent of prey items, while songbirds may up an additional 47 percent. On Vancouver Island, red squirrels appear to be most important prey species, at least during the early breeding season. Flickers, thrushes, sapsuckers, murrelets, and bats were also taken.

On Vancouver Island, 11.8 percent of the forested land base is protected from logging. On the Queen Charlotte Islands, 22.4 percent is protected. Much of the protected land, however, is in higher elevation forests where few goshawks have been found.

Photo © Robin Silver