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Set free: an evaluation of two break-away mechanisms for tracking collars

Povh, L.F., Willers, N. and Fleming, P.A.ORCID: 0000-0002-0626-3851 (2022) Set free: an evaluation of two break-away mechanisms for tracking collars. Wildlife Research . Online Early.

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Context: One of the welfare and ethical challenges with tracking animals is ensuring that the tracking device is removed from the animal at the conclusion of the study. However, for animals that are not readily re-trapped, the impact of devices and alternatives for their retrieval are rarely examined.

Aims: We compared the retention time of two types of break-away mechanisms for tracking collars deployed on mainland quokkas (Setonix brachyurus).

Methods: We tested a cotton thread (CT) weak-link, where the collar was cut and then a looping stitch was made to link the cut ends of the collar. We compared collar retention time of this simple mechanism with a lightweight automatic micro timed-release device (mTRD, Sirtrack).

Key results: Of the 17 radio collars with CT, the fates of 15 collars contributed to retention time data. Seven collars released: six fell off and were recovered 148 ± 64 (s.d.) days after deployment and another collar fell off 136 days after deployment but could not be recovered. Eight quokkas were recaptured (161 ± 109 days after deployment) and collars removed. Two quokkas were each tracked for over a year but then disappeared. Of the 11 GPS collars fitted with a mTRD, the fates of nine collars contributed to retention time data. Two released early at 16 and 29 days and were recovered. Seven fell off around the scheduled release date. There were two unknown fates. Re-trapped collared quokkas did not show evidence of injuries from wearing collars or any significant change in body mass (P = 0.442).

Conclusions: The timing of release for the CT weak-link was unpredictable, with a third of the collars releasing within 1 year and 7/15 lasting only about 6 months. Over two-thirds (7/9) of the GPS collars fitted with timed-release device released on schedule while 2/9 released early.

Implications: Tracking devices equipped with break-away mechanisms are essential for safeguarding animal welfare outcomes for species where the chance of recapture is not certain. For both break-away types examined in this study, the release timing was unpredictable and poor collar recovery rates show the importance of adding camera traps to monitor the outcomes for collared animals.

Item Type: Journal Article
Murdoch Affiliation(s): Centre for Terrestrial Ecosystem Science and Sustainability
Publisher: CSIRO Publishing
Copyright: © 2022 The Author(s) (or their employer(s)).
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