Surgical implantation of temperature-sensitive transmitters and data-loggers to record body temperature in koalas (Phascolarctos cinereus)
Adam, D, Johnston, SD, Beard, L, Nicholson, V, Lisle, A, Gaughan, J, Larkin, R, Theilemann, P, McKinnon, A & Ellis, W 2016, Australian Veterinary Journal, vol. 94, nos. 1-2, pp. 42-47.
With climate change predicted to influence the distribution of koala populations throughout Australia’s east coast, the individual responses of koalas to unsuitable temperatures may have important conservation implications. Accordingly, in this study, the suitability of temperature-sensitive intra-abdominal implants for tracking koala core body temperature was assessed. Findings were consistent across all koalas, revealing body temperatures ranging from 34.2﮿C to 37.7﮿C.
Study animals consisted of four rehabilitated koalas, housed in an outdoor enclosure for a period of three months. Surgical implantation of the transmitters was carried out either by suturing the device to the internal abdominal wall or by placing it within the peritoneal cavity, without attachment. Devices were surgically removed after the study period. Surgical implantation progressed without complication, with all koalas recovering from the procedure. However, suturing of the transmitter resulted in minor inflammation and thus, the free-floating method was favoured. Furthermore, surgery duration was significantly shorter for the free-floating technique. Data collected from the transmitter was ‘noisy’, with unrealistic temperature values occasionally displayed; however, when trimmed of such values, readings were consistent. ‘Noisy’ data is likely to have resulted from local disruptions, caused by nearby electrical equipment and thus, this complication may not arise upon wild-release of the koalas. A diurnal rhythm in body temperature was observed, with minimum and maximum temperatures recorded between 06:00-10:00 and 16:00-19:00 respectively. Mean daily variation in temperature was 0.6﮿C and increases in body temperature appeared to be associated with intensity of each individual’s activities (e.g. feeding versus movement along perch). The greater range of body temperature demonstrated in this study compared to the current literature may have manifested in response to fluctuating ambient temperatures, which differ from the koala’s thermoneutral zone.
The successful implantation of temperature loggers for remote tracking of koala body temperature, as reported by this study, allows for future investigation of behavioural response to temperature extremes. Such research is likely to provide a more accurate representation of the implications of future climate change, and examining potential coping mechanisms at the individual level.
Summarised by Julian Radford-Smith
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