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Dusky Canada geese nest principally on the Copper River Delta in Alaska and winter in the Willamette Valley, Oregon and along the lower Columbia River in south-west Washington and northwest Oregon. The Good Friday earthquake in 1964 elevated the delta 6-10 feet, resulting in the invasion of scrub-shrub habitat over much of the delta, and access by predators such as coyotes and brown bears. Consequently, the population began declining, subsiding below 10,000 by the mid to late 1980’s. Dusky geese had been virtually the only race of geese wintering in northwest Oregon and south-west Washington, but beginning in the late 1970’s-early 1980’s, Taverner’s geese began wintering in the Willamette Valley as well. Additionally, in the 1990’s cackling geese, which formerly wintered in the Sacramento Valley in California, began overwintering in these areas, too. A local, nonmigratory population of Western Canada geese has also become established. All the populations, except Dusky Canada geese, are stable or increasing. As a consequence of these events, management of the precarious Dusky population has become quite complex. Drs. Bob Jarvis and Bruce Dugger and their graduate students have studied these populations on the wintering and breeding grounds to better understand the dynamics of the changing scenario and to help management agencies modify their management strategies.
Conservation Assessment for the Dusky Canada Goose (Brant canadensis occidentalis Baird). 2003. Bromley, Robert G. and Thomas C. Rothe. Pacific Northwest Research Station General Report PNW-GTR-591.