Population ecology of polar bears in western Alaska and adjacent portions of Russia. Polar bears (Ursus maritimus) are seasonal residents of the Bering and Chukchi seas during ice bound months of November through May. However, knowledge of seasonal use patterns and densities of polar bears in the Bering and Chukchi seas was largely unknown. Polar bears were captured throughout the Bering and Chukchi Seas adjacent to the Alaskan and Russian coastlines in the spring and adult females were fitted with satellite telemetry collars that provided regular position locations using overflying satellite technology. Data from these satellite instrumented polar bears indicate that the Chukchi Sea population is shared with Russia. These data are being used to delineate the population bounds and define the seasonal limits of polar bear distributions in the Bering and Chukchi seas. This effort will also determine the degree of discreteness between the adjacent populations. Denning areas have also been identified and the use of aerial den surveys in Russian territory as a population estimation procedure will be investigated in cooperation with Russian scientists. Detailed movement data currently available is limited to adult females as male polar bears can not be fitted with neck collars. A pilot study of subcutaneous implantation of satellite transmitters with percutaneous antennae is being conducted to determine the feasibility of using this technology to test the assumption that adult male polar bears have similar movement patters as adult females. Polar bears have long life spans, delayed maturity, small litter sizes, and extended reproductive intervals. These population characteristics indicate that any increases in direct mortality of polar bears that may result from industrial activity or subsistence hunting may not be compensated by increased productivity of polar bears. Mortality of neonatal cubs and immature animals is believed to be the major source of mortality to polar bears populations as radio-telemetry data indicate high sur... rates of adult bears. A pilot study to develop suitable telemetry technology to remotely detect cub mortality is being initiated during spring 1998. A satellite-linked detection system will be tested on two family groups to determine if the current state of satellite telemetry can reliably detect disappearance of cubs from family groups.