Surgical implantation of temperature-sensitive transmitters and data-loggers to record body temperature in koalas (Phascolarctos cinereus) D Adam, a,b * SD Johnston, a,b L Beard, a,b V Nicholson, c A Lisle, a,b J Gaughan, a,b R Larkin, d P Theilemann, a,b A Mckinnon d and W Ellis a,b Background Under predicted climate change scenarios, koala distribution in Australia is expected to be adversely affected. Recent studies have attempted to identify suitable habitat, based on models of bioclimatic regions, but to more accurately reflect the thermal tolerance and behavioural adaptations of the various regional populations, the koala’s response to periods of heat stress will need to be investigated at the individual animal level. Objective To explore the safety and suitability of temperature- sensitive intra-abdominal implants for monitoring core body temperature in the koala. Methods A temperature-sensitive radio transmitter and thermal iButton data-logger, waxed together as a package, were surgically im- planted into the abdominal cavity of four captive koalas. In one animal the implant was tethered and in the other three, it was left free-floating. Results After 3 months, the implants were removed and all four koalas recovered without complications. The tethering of the package in the one koala resulted in minor inflammation and adhesion, so this practice was subsequently abandoned. The free-floating deployments were complication-free and revealed a diurnal body temperature rhythm, with daily ranges of 0.4–2.8°C. The minimum recorded body temperature was 34.2°C and the maximum was 37.7°C. The difference in the readings obtained from the transmitters and iButtons never exceeded 0.3°C. Conclusions The suitability of the surgical approach was confirmed, from both the animal welfare and data collection points of view. Keywords body temperature; climate change; koalas; surgical implants Abbreviations RH, relative humidity; T b , body temperature; T a , ambient temperature Aust Vet J 2016;94;42–47 doi: 10.1111/avj.12393 T he koala (Phascolarctos cinereus) is the largest and most iconic of Australia’s arboreal marsupials, but free-ranging populations are in decline across much of their range through loss of habitat, introduced predators, disease and vehicle strikes. 1 The trend of warming air temperatures in Australia in the past decade is consistent with those measured globally, 2,3 such that projections for the effect of climate change include: increased maximum and minimum air temperatures; increased incidence and prolonged duration of drought; and significant changes to the patterns of rainfall. 3 The northern regions of Queensland have already experienced an increase in mean annual precipitation, while southern parts of Queensland have been exposed to a below average rainfall pattern over the past decade. 4 As suitable habitat and environmental conditions decline across Australia under pre- dicted climate change scenarios, koala distribution is expected to contract further. 5,6 Recent studies that have attempted to identify suitable koala habitat, both present and predicted, have been based on models of the availability of bioclimatic regions, 7 but have been silent on the koala’s physiological plasticity or thermal niche requirements. Hence, the koala’s response to periods of heat stress will need to be investigated at the individual animal level. We aim to eventually measure body temperature (T b ) in free-ranging koalas to estimate the critical limits of T b that drive habitat and microclimate selection. These variables can then inform models that more accurately reflect the thermal tolerance and behavioural adaptations of the various regional populations. As a prelude to a field study of T b in free-ranging koalas, we investigated the logistics and animal welfare considerations of the intraperitoneal implantation of temperature-sensitive radio transmitters and iButton data-loggers. These techniques have been used in a range of wildlife species, including the platypus ( Ornithorhynchus anatinus), 8 short-beaked echidna ( Tachyglossus aculeatus ), 9 Tasmanian devil (Sarcophilus harrisii) 10 and Tasmanian bettong (Bettongia gaimardi). 11 Thermal data-loggers have the advantage of recording data continuously without the need to maintain contact with the animal. On the other hand, radiotelemetry allows direct observations and real-time T b readings, but it is also necessary to maintain contact with the study animal. We not only combined these technologies in the same animal to maximise data recording, but also as a means of validating one technique against the other; a similar approach has been used in dromedary camels (Camelus dromedarius). 12 To date, the only reports of T b in the koala are from rectal measurements in captive animals. 13–15 We assessed the safety and feasibility of two different surgical implantation approaches to monitor body temperature in four captive koalas. *Corresponding author. a University of Queensland, School of Agriculture and Food Science, Gatton Campus Gatton Queensland 4343, Australia; d.adam@uq.edu.au b Wildlife Science Unit, School of Agricultural and Food Sciences, The University of Queensland, Gatton, QLD, Australia c Dreamworld, Coomera, QLD, Australia d Moggill Koala Hospital, Department of Environment Heritage and Protection, Moggill, QLD, Australia © 2016 Australian Veterinary Association 42 WILDLIFE & ZOOS WILDLIFE & ZOOS Australian Veterinary Journal Volume 94, No 1-2, January/February 2016