Subcutaneous implantation into polar bears (Ursus maritimus) of

satellite transmitters with a percutaneous whip antenna

Daniel M. Mulcahy

and

Gerald Garner

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

1011 East Tudor Road Anchorage, AK 99503

Satellite telemetry has long been used to follow the seasonal movement patterns of free-ranging polar bears (Ursus maritimus). The satellite transmitters are incorporated into neck collars which limits the technique to female polar bears only. Male polar bears have necks of wider diameter than their heads and quickly shed a neck collar. This inability to effectively attach satellite transmitters to male polar bears forces an assumption that movement and distribution of males and females are similar. The validity of this assumption directly affects efforts to define populations of polar bears genetically and geographically. Other methods of attachment of both VHF radio and satellite transmitters have been attempted with little success. Satellite transmitters have been glued to the fur on the base of the neck of polar bears, but these units failed or were. An ear tag satellite transmitter tag failed within 10-30 days of deployment. Relocation and recapture of the animals was not possible in either of these cases to determine the cause of failure.

Subcutaneous transmitter implants have been used successfully in small mammals where external transmitters were not practical. Abdominal transmitter implants with coiled internal antennae have been used successfully in river and sea otters. Abdominal implantation of VHF radio transmitters has been tried on a very limited scale in bears, including a polar bear. Subcutaneous implantation of VHF radios was done in initially in black bears but the method was not further used. Subcutaneous or abdominal implantation of satellite transmitters requires the use of a percutaneous antenna due to the comparatively weak signal strength of satellite transmitters compared to conventional radio transmitters. The introduction of a catheter collar developed to prevent infection caused by bacteria migrating along long-term, indwelling catheters has permitted successful use in birds of abdominal satellite transmitters with a percutaneous antenna.

We developed methods for the subcutaneous implantation of satellite transmitters in male polar bears. The major challenge was to find methods permitting the surgeries to be done in the outside on the sea ice of the northern coast of Alaska, where the temperatures experienced during surgery were as low as -22 degrees F. Sterilized polypropylene glove liners were worn under surgical gloves. The minor bleeding from the incision never stopped, probably because the clotting cascade was slowed by the cold temperatures. Injectable drugs froze in vials and syringes. Instruments froze to blood on the surgeon's hands. Plastic or paper drapes shattered and tore when used. Speed was the best overall solution to the problems that were due to the extreme temperatures.

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