# The Life of Brian … and David: Two Flying‐Foxes' Contribution to Science

## TL;DR

This study examines if tagging and implanting devices on wild bats negatively affects their welfare, using data from two bats over several years.

## Contribution

The paper provides rare long-term data on the welfare impacts of telemetry devices in free-living flying-foxes.

## Key findings

- Long-term monitoring of Brian and David showed negligible impacts from thumb bands and transmitters.
- Necropsy findings supported the conclusion that the procedures did not harm the bats' welfare.
- The study highlights the value of long-term data for understanding telemetry effects on wildlife.

## Abstract

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.

This Nature Note examines whether thumb bands and surgically implanted temperature transmitters adversely affect the welfare of free‐living grey‐headed flying‐foxes. Long‐term monitoring and necropsy findings from two males, Brian and David, suggest negligible impacts of these procedures on individual welfare. Although based on only two cases, the rare long‐term data provide valuable insight into post‐procedure outcomes for telemetry‐equipped wildlife.