U.S. Geological Survey, Biological Resources Division, Alaska Science Center

1011 E. Tudor Road Anchorage, Alaska 99503 USA

  MICHAEL K. STOSKOPF

Companion Animal and Special Species Medicine, College of Veterinary Medicine, North Carolina State University

4700 Hillsborough Street, Raleigh, North Carolina 27606 USA

 Abstract. We documented extrusion and loss of abdominally-implanted radio transmitters with percutaneous antennas from adult female Harlequin ducks (Histrionicus histrionicus). Radio implants and recaptures occurred during wing molt (late August to mid-September) in 1995-1997. Of 44 recaptures of Harlequin ducks implanted with radios, 7 (16%) had lost their transmitters and 5 (11%) had radios in the process of extruding. Most (11 of 12) extrusions and losses occurred in birds implanted with radios in 1996 and recaptured in 1997. We suggest that transmitter extrusions and losses were due largely to change in design between 1995 and 1996. Transmitters implanted in 1996 were cylindrical rather than spherical, had a flat end with an abrupt edge, and the lower portion of the antenna was reinforced. Radio losses occurred after the 7 month monitoring period and caused no apparent detriment to the birds. Investigators using implanted radios with percutaneous antennas for long-term projects should be aware of the potential for radio extrusion and should design transmitters to minimize the problem.