Colour-ring wear and loss effects in citizen science mark-resighting studies

Allen, Andrew M., Ens, Bruno J., van de Pol, Martijn, Van Der Jeugd, Henk, Frauendorf, Magali, Van Der Kolk, Henk Jan, Oosterbeek, Kees, Nienhuis, Jeroen, and Jongejans, Eelke (2019) Colour-ring wear and loss effects in citizen science mark-resighting studies. Avian Research, 10 (1). 11.

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Background: Ring wear and loss may have important consequences for mark-recapture studies that aim to estimate survival trends. Our study quantifies the rates of wear and loss from a long-running colour-ringing project of the Eurasian Oystercatcher (Haematopus ostralegus) in the Netherlands. Methods: Our analysis included 8909 colour-ringed oystercatchers with 118,071 resightings, predominantly ringed and observed by citizen scientists. We quantified how ring wear and loss may vary with ring colour and age, and how this may impact resighting probabilities. We then determined how ring loss may impact survival estimates and resighting probabilities of mark-recapture models by simulating four scenarios of how citizen scientists may resight and report birds with lost colour rings. Results: Annual rates of colour ring loss averaged 2.5% compared with 1% for ring wear, but lost rings also had a higher reporting probability (31.2%) than worn rings (10.3%). Lost rings may not directly impact survival estimates since 50% of oystercatchers with lost rings could still be uniquely identified. Ring wear and loss rapidly increased between 10 and 15 years after ringing. Rates of ring loss were comparable amongst ring colours, but the wear rate appeared higher for red and white rings compared to other colours. Rates of ring wear and loss varied significantly amongst different regions in our study, which were characterised as having different habitat features. Differential rates of ring wear may have important implications for studies conducted over large geographical scales or of multiple species. Conclusions: Based on simulations of ring loss in our population, estimates of apparent survival may be 0.3-1.2% lower whilst the impact of ring wear was deemed even lower. We developed a table of recommendations containing advice for ring fitting, data collection, study design, and mark-recapture analyses, so that future colour-ringing studies can benefit from our experiences in collecting and analysing data of ring wear and loss through citizen science.

Item ID: 69631
Item Type: Article (Research - C1)
ISSN: 2053-7166
Keywords: Bias, Bird migration, Citizen science, Colour-ring, Mark-recapture, Shorebirds, Survival
Copyright Information: © The Author(s) 2019. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.
Date Deposited: 14 Oct 2021 23:50
FoR Codes: 31 BIOLOGICAL SCIENCES > 3103 Ecology > 310307 Population ecology @ 100%
SEO Codes: 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280102 Expanding knowledge in the biological sciences @ 100%
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