Reproductive ecology and survival of dusky Canada geese. The Copper River Delta contains the largest known concentration of breeding dusky Canada geese (Branta canadensis occidentalis). Elevational and hydrological changes following the 1964 earthquake resulted in large scale habitat changes. Concurrently a large scale commercial salmon fishery developed in the area supplemented by enhanced stocks. Subsequently, large changes in the local predator community were noted , and populations of duskys declined to their lowest recorded levels since surveys began in the 1970s. The current population is approximately 10,000 birds. The management plan for dusky Canada geese requires complete closure of sport hunting if the population falls below a threshold level of 8,000 birds. Accurate estimates of the breeding population size and productivity are necessary to effectively manage dusky Canada geese. However, extensive renesting may bias visibility correction factors thereby inflating estimates of the breeding population size. U.S. Fish and Wildlife Service (USFWS) determines visibility corrections for aerial surveys from a ratio of the number of nests found on ground surveys to the number of pairs estimated from aerial surveys. If renesting is common, then visibility corrections are too high and result in overestimates of the breeding population size when applied to the result of aerial surveys. Ground surveys of nesting dusky Canada geese conducted by U.S. Forest Service (USFS) indicate a wide range of nest initiation dates in the Copper River Delta. By comparison, cackling Canada geese (Branta candensis minima) initiate nests over a much shorter interval. Furthermore, dusky nesting success is low, and Canada geese renest. The combination of low nesting success and an extended period of nest initiation led observers to conclude that up to 25% of dusky nests could be renests . Understanding the factors limiting these productivity parameters is of increasing importance as the population declines and managers exhaust the options for harvest management. The Dusky Canada Goose Subcommittee of the Pacific Flyway Study Committee also identified renesting ecology and gosling survival as important information needs for the management of the population. Available information suggests that nest success and gosling survival in the Copper River Delta are very low. Apparent nest success for duskys in the Copper River Delta was estimated at 88%, but had fallen to 43% in the early 1980s. Recent data suggest that nest success may be below 10% . Nest predators include brown bear (Ursus arctos), coyote (Canis latrans), parasitic jaegers (Stercorarius parasiticus), and glaucous-winged gulls (Larus glaucescens). Previous research attributed 50% of nest loss to brown bears, 20% to canids, and 16% to avian predation. However, he based his estimates on the identification of predators from evidence following depredation, and did not estimate nest success or predation rates using maximum likelihood methods (Heisey and Fuller 1985). Such estimates are subject to large bias when the probability of finding destroyed nests is low. Dusky Canada geese are surveyed in late summer to estimate productivity. Indices of productivity are derived from age ratios observed on those surveys. If geese that lose their entire brood emigrate to other areas or otherwise become segregated from brood flocks then productivity estimates will be too high. Conversely, if brood flocks are underrepresented in surveys then productivity indices will be too low. Studies of radio-marked broods will provide critical information for the evaluation of production indices based on gosling survival and the movements of adult geese. Because of the improvements in techniques for monitoring nests and analyzing the results the proposed study of nest success does not unnecessarily duplicate previous research. Furthermore, demographic studies of renesting, and adult female and gosling survival of dusky Canada Geese have not been previously conducted. Finally, an average 2.6 carcasses of adult dusky Canada geese per km2 were found on the nest plots. These carcasses indicate that survival of nesting adults may be poor. Adult survival has a much greater potential to influence the population trend in goose populations than does nesting success. Estimating survival on the breeding grounds will provide additional information for further examination of the timing and causes of mortality of adults.