Summary
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 infiltration. 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 longevity of these transmitters at the lower pulse rates would substantially exceed 1 year. This transmitter 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.