Water bird abundance and distribution in the Bristol Bay region, Alaska

Platte, Robert; Butler, William

We flew aerial surveys to estimate abundance and delineate distribution of water birds in late May 1993 and 1994 in the Bristol Bay region (BBR), Alaska. We estimated about 360,000 ducks, 4,000 geese, and 4,000 loons were present on BBR, 1993-1994. Scaup were the most numerous duck species each year, comprising 27% of the duck population. Other abundant species included northern pintails, black scoters, green-winged teal and mallards. Coefficients of variation for population indices of abundant species were 10-15%. We used a computerized geographic information system (GIS) to map water bird densities. Most species showed a highly patchy distribution reflecting the patchiness of habitat in the survey area. Scuap and black scoters occurred in relatively large, widely distributed patches whereas mallards, pintails and teal occured in small patches scattered thoughout the survey area. Wetlands along the upper Alaska Peninsula between Naknek and Pilot Point contained the highest densities of water birds in the survey area. Density distribution maps are presented for abundant species. Our areial survey design and GIS analyses provide detailed water bird abundance and distribution information. Results can be compared to the North American Waterfowl Breeding Population Survey data in the BBR to evaluate both surveys and to design subsequent surveys to meet specific objectives. Density maps can be used as data layers for creating stratified survey designs and examining relationships between remotely sensed habitat data and water bird distribution.