Novel use of in-stream microchip readers to monitor wild platypuses.

Abstract

A variety of techniques have been used to monitor platypus populations to assess the impacts of the threats they face, but each technique has limitations. In this study we investigated the novel use of in-stream microchip readers, to remotely monitor the movements of microchipped wild platypuses. Over 13 months, we recorded movements of 18 microchipped individuals past nine fixed locations in the Inglis Catchment in northwest Tasmania, using three units of which all were capable of detecting Trovan® unique microchips and two were additionally capable of detecting ISO microchips. Each site was monitored one or two times, for durations of 8–39 days. We undertook direction of movement investigations during two monitoring periods, by placing the antennas from two systems in the same creek within 3 m of each other. In a total of 264 days of monitoring, 528 platypus observations were made from 18 individual platypuses, consisting of 13 of 18 (72%) platypuses captured at the monitoring sites within 16 months prior to monitoring, two platypuses captured at other sites in the same time period, and three of seven (43%) individuals microchipped 3–5 years previously. This number of platypus observations, in combination with the stable number of platypuses observed per day, the range of movement behaviours recorded and the results of the direction of movement investigations, indicates that at appropriate sites, in-stream microchip readers are an effective method of monitoring the movements and survivorship of microchipped wild platypuses.