An Improved Radio Transmitter and Implantation Technique for Snakes

Radio transmitters for implantation in snakes were designed to provide transmitter life in excess of one year. This was achieved by using a 290 mAh, 3.5 V Lithium-Thionyl Chloride battery and a 2 stage transmitter with a thermistor in the timing circuit to reduce drain at low temperatures. Also, a hermetic metallic housing was designed to protect against body fluid infil- tration. The transmitter and 20 cm whip antenna were both implanted subcutaneously. Field trials with 7 telemetered black rat snakes (Elaphe obsoleta) indicated normal reception at a range of 150- 300 m. Snakes were located on 423 of 465 (91%) searches during the period they were active. The transmitters with the highest pulse rate were still active after 12 months indicating that the lon- gevity of these transmitters at the lower pulse rates would substantially exceed 1 year. This trans- mitter and implantation technique is ideal for large snakes that spend inactive periods at a reduced body temperature. Transmitter longevity would decrease with snakes that were active year round. The tremendous increase in recent years in the use of radiotelemetry in the study of free-living animals attests to the value of the technique in providing information that was previously unob- tainable. Specifically, one is able to re- peatedly relocate known individuals and thereby gain insight into various aspects of movement and associated be- haviors. Implicit in the use of radiote- lemetry is the assumption that the be- havior of the telemetered animal is