GREAT-BASIN CANADA GOOSE NESTING ON THE MID-COLUMBIA RIVER, WASHINGTON - AN HISTORICAL-PERSPECTIVE AND UPDATE, 1981-1990

Nesting of Great Basin Canada geese, Branta canadensis moffiti, on 20 islands in the Hanford Reach of the mid-Columbia River has been survey ed since 1953. Nest counts declined from over 300 in 1958 to a low of 108 in 1975. Since then, nest counts increased to a peak of 274 in 198 9. The decline in 1960-1975 is attributed to the complete loss of Lock e Island as a nesting habitat caused by persistent coyote, Canis latra ns, predation. In the early years, Locke Island alone accounted for 30 to 50% of the nests in the Hanford Reach. The increase in nest counts after 1975 reflects increasing nest density on islands downriver from Locke Island. Downriver islands were historically relatively free fro m coyotes. In 1989 and 1990, 70% of the nests were on five downriver i slands near the city of Richland. The average annual nest count for 19 81-1990 was 215. Eighty percent of the nests were successfully hatched . The occurrence of unsuccessful nests was attributed to depredation 8 .4%, nest abandonment 7.7%, flooding 2.6%, and 0.5% of the successful nests had infertile eggs. These observations document year-to-year cha nges in the island nesting population of Canada geese along the last r emaining unimpounded section of the Columbia River in the United State s. Population changes are related to the changing environment, includi ng coyote predation, in eastern Washington. These studies demonstrate the value of long-term monitoring in assessing environmental change.