Pentosidine levels cannot be used to age a long-lived seabird

ABSTRACT

Robust measurements of age are important for investigating ecological processes. In particular, seabirds, which form a major part of the coastal and marine ecosystems, may use and respond to their environment differently based on their age. This study aimed to determine whether pentosidine, a biological marker of age which was previously reliably used to age other avian species, could be used to age Bridled Terns (Onychoprion anaethetus) breeding on Penguin Island, Western Australia. It was found that patagial skin collagen-bound pentosidine cannot be used to determine the age of Bridled Terns because of low collagen levels in skin samples and that, overall, there was a low recapture rate of birds born on the island (less than 5% of the birds trapped in this study). Bridled Terns’ diet and life at sea may explain their low skin collagen levels, but some molecular adaptations and antioxidants from their diet may help them resist oxidative challenge. Hence, methods for ageing birds based on collagen content in skin samples may not be uniform across species. Furthermore, low recapture rates in this colony may indicate high levels of dispersal or mortality, which warrant further investigation.

KEYWORDS:

• Bridled Tern
• collagen
• ageing
• hydroxyproline
• pentosidine
• seabird

Acknowledgements

The authors would like to thank the University of West Virginia and particularly Crissa Cooey for analysing the samples and providing feedback on the preliminary results, as well as Prof. Matthieu Le Corre, Prof. Chris Feare and Dr Lachlan McLeay for their feedback through the examination of Aurélie’s Ph.D. thesis. The authors would also like to thank the two anonymous reviewers and Dr Kate Buchanan who provided feedback on the manuscript. This research was undertaken with a number of permits and regulations: Animal Competency and Experience Registration (Murdoch University), Animal Ethics Committee Permit (R2603/13), Australian Bird and Bat Banding Schemes Banding Authority Number 2943, Department of Parks and Wildlife Regulation 4 (Authority to enter CALM land and/or waters): CE005025, CE004529, CE004213, Regulation 17 (Licence to take fauna for scientific purposes): SF009937, SF009561, SF010526, Regulation 23 (Licence to take and mark fauna for research purposes): BB003316, BB003167, Wildlife Trade Permit WTP-1536889-1695, and Department of Agriculture and Food Licence to use animals for scientific purposes. A. M. T. Labbé was the recipient of the Robert Hammond Research Grant at Murdoch University. We would also like to thank all the volunteers who assisted with the fieldwork, particularly Brent Savage and Heidi Nore.

Geolocation information

The study took place on Penguin Island, Western Australia, WGS84 32°18′19″ S, 115°41′28″ E.

Additional information

Funding

This work was supported by the Robert Hammond Research Grant at Murdoch University.