Performance of implantable satellite transmitters in diving seabirds

We report on the first deployment of satellite transmitters in large alcids . In 1995 and 1996, we surgically implanted 51 transmitters in Common and T hick-billed murres (Uria aalge and U. lomvia) and Tufted Puffins (Fratercul a cirrhata) at three colonies in Alaska. These devices furnished more than 2,900 locations over succeeding months (eight months maximum transmitter li fe), some 30-40% of which had calculated errors of <1,000 m. We considered other data to be reliable if locations were repetitive within a short perio d of time. As measures of data collection efficiency, we calculated locatio n indices (number of locations per hour of transmission) of 0.44 during the breeding season and 0.35 overall. Those values compared favorably with sat ellite transmitters previously deployed on large mammals at similar latitud es. Transmitters did not last as long as expected because lithium batteries tended to self-discharge when kept at the high internal temperature of a b ird. Most importantly, we encountered high mortality of instrumented birds, especially in the interval from 11-20 days after release. Our results sugg est that radio transmission itself somehow impaired normal feeding behavior or otherwise compromised the birds' health. Those two problems (battery li fe and bird mortality) will need to he solved before implantable devices ca n he applied effectively to the same or similar species in the future.