Radio-Telemetry Transmitters for Use in Studies of the Thermoregulation of Unrestrained Common Wombats, Vombatus ursinus

Abstract

The designs of radio-telemetry transmitters used in a study of thermoregulation in the common wombat, Vombatus ursinus, are described. A single-channel implantable transmitter, weighing 25 g and with a range of 100 m, was designed to monitor deep body temperature. Two versions are described of an externally mounted transmitter used to monitor heart rate and physical activity. In the first, each heartbeat was transmitted as a single radio-frequency pulse of short duration; this technique conserved power but was found to be unreliable for monitoring very low heart rates. In the second version, the electrocardiogram waveform was transmitted as a frequency-modulated signal. The multichannel transmitters weighed 300 g with batteries, and had a range of up to 400 m. A transducer consisting of a multiposition mercury switch was used to monitor activity. Changes in orientation of the transducer were transmitted as different audio-frequency tones.