Using acoustic telemetry to monitor foraging by penned mule deer

Abstract Using a digital camcorder and commercial wireless microphone and receiver components, we developed an acoustic telemetry system for remotely monitoring and recording a variety of sounds generated by 3 desert mule deer (Odocoileus hemionus eremicus) held in an outdoor enclosure. We offered the deer water and several types of feed and obtained 1,500 minutes of audio-visual records of feeding, drinking, and other behaviors. We determined that attaching a microphone to a shaved patch of the animals' cranial region produced more complete and higher-fidelity signals than did collar placement of the microphone. Based on audible sounds alone, 10 briefly trained observers accurately distinguished among deer feeding, drinking, and ear-flapping bouts, and had good to excellent success in identifying 4 foods consumed by the deer. We also undertook preliminary sound signal analysis of deer feeding bouts but concluded that machine classification and enumeration of deer behaviors will require additional development. Our system provided a simple, relatively inexpensive, but powerful means of monitoring detailed foraging behaviors of ungulates at <200 m. It may thereby facilitate and enhance foraging and time budget studies of captive or approachable subjects.