Seasonal movements and pelagic habitat use of Alaska seabirds determined by satellite telemetry. The Alaska Maritime National Wildlife Refuge provides protection of breeding habitat for about 70% of the seabirds that nest in Alaska. These birds spend about 80% of their time in marine habitats that are not protected, however, and they are therefore subjected to various threats including oil pollution and other contaminants, gillnet mortality, and competition with commercial fisheries. When populations decline, researchers and managers tend to focus their search for explanations and remedial actions on the breeding season, because standard observational studies are feasible only during that portion of the annual cycle. In reality, the relevant factors may operate more often in winter, possibly at great distances from where the declines are detected. This situation promotes faulty conservation planning and action. To provide better protection for seabirds during the vulnerable at-sea portions of their daily and annual cycles, it is necessary to identify key areas where populations from particular colonies congregate to feed and overwinter. Telemetry offers a cost-effective approach for doing this, whereas conventional methods do not. Banding programs, in particular, are ineffective because of the low recovery rates typical of oceanic birds. Satellite transmitters have been used extensively for telemetry of large mammals since the mid 1980s. Applications to birds have been limited mainly by the size and weight of transmitter packages, and most studies have targeted larger species such as penguins, albatrosses, swans, and geese. Recently, the availability of transmitters in the 30-50 g size range has permitted satellite tracking of species as small as 1,000 g (Petersen et al. 1995, Condor 97:276-278; Falk and Moller 1995, Polar Biol. 15:495-502). In an earlier study, Hatch et al. (submitted) used surgically implanted satellite transmitters to determine the summer foraging patterns and wintering grounds of murres (Uria aalge and Uria lomvia) and tufted puffins (Fratercula cirrhata) from four colonies in Alaska. High mortality of instrumented birds was encountered, and the investigators concluded that technical problems will need to be solved before implantable devices can be applied effectively to the same or similar species in the future. In consequence of recent (1997-1998) improvements in transmitters and receiving systems, users can now expect to gather more data, of higher quality, using devices less likely to influence the health or behavior of the animals studied. Because non-alcid species are larger than murres and puffins, they are worthy of field trials using available methods and equipment . The problems encountered previously in murres and puffins may yield to laboratory-based research on attachment techniques and the biological effects of instrumentation. Thus, the specific objectives of this project are to (1) determine the suitability of current-generation equipment and attachment techniques for satellite tracking of non-alcid species of seabirds in Alaska; (2) develop alternative or refined techniques for attachment of satellite transmitters to large alcids that alleviate problems of altered behavior and mortality in the field, and then (3) determine the location, fidelity, and degrees of overlap in the wintering areas of murres from widely spaced colonies in the Gulf of Alaska and Bering Sea.