The Life of Brian … and David: Two Flying-Foxes' Contribution to Science.

The welfare of free-living animals in scientific studies must always be in question: do procedures and devices deployed on wildlife negatively affect their welfare? In December 2018, we captured two wild, male grey-headed flying-fox (Pteropus poliocephalus), given the names Brian and David, at Adelaide Botanic Park, South Australia. Brian and David, two of nine bats captured, were estimated to be 3 and 5 years old. We tagged the bats with thumb bands and surgically implanted a transmitter to monitor body temperature. Following release, body temperature data were collected (21 and 65 days, respectively). Brian was found deceased in June 2025, 6.5 years later, 2.6 km from the capture site. David was found deceased in April 2024, 5.3 years later, 9.4 km from the capture site. A necropsy was performed on each bat. This research note addresses the question: do thumb bands and transmitter implantation negatively affect the welfare of flying-foxes? Through Brian and David's case studies, detailing the procedures, physiological data and necropsy findings, we present observations to suggest that, in these individuals, these procedures and devices had negligible impacts. While the case of two individuals offers limited power for broader inference, long-term post-procedure data of telemetry-equipped animals is rare, making these observations valuable to report. We thank these bats' involuntary but valuable contribution to science and present this research note to celebrate the life of Brian and David.