Conservation Assessment for the Dusky Canada Goose ('Branta canadensis occidentalis Baird');Forest Service general technical rept

摘要

Dusky Canada geese compose one of the smallest populations of geese in North America and have exhibited a marked decline in the past 30 years. A comprehensive synthesis of past and current biological information on the subspecies has been compiled to provide insights into the ecology and demography of the population, as well as explore management efforts to promote long-term conservation. Duskys occupy a discrete range, which has allowed the development of focused, long-standing management programs. The 1964 Alaska earthquake set in motion significant ecological changes in wetlands, plant communities, and the suite of predators on the dusky goose breeding grounds. A subsequent decline in goose productivity has become the primary challenge to this population. Concurrently, habitats on the western Washington and Oregon wintering grounds became more favorable for geese, but over 250,000 Canada geese of five other subspecies now occupy the region where formerly duskys were the majority. In the 1960s, the harvest of dusky geese was recognized as a primary management concern and regulation was effectively implemented. At present, protection of diminished duskys amid 10 times as many other Canada geese has created great complications for both management of hunting and attention to increasing complaints of crop depredation by wintering flocks. Important information needs are suggested to improve population monitoring, evaluate specific causes of lost productivity, and assess the direction and effects of succession of breeding ground habitats and conversion of winter habitats.