Computer-assisted photo identification outperforms visible implant elastomers in an endangered salamander, Eurycea tonkawae

Hemmi, J. M., Bendik, N. F., Morrison, T. A. , Gluesenkamp, A. G., Sanders, M. S. and O’Donnell, L. J. (2013) Computer-assisted photo identification outperforms visible implant elastomers in an endangered salamander, Eurycea tonkawae. PLoS ONE, 8(3), e59424. (doi: 10.1371/journal.pone.0059424) (PMID:23555669) (PMCID:PMC3605430)

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Despite recognition that nearly one-third of the 6300 amphibian species are threatened with extinction, our understanding of the general ecology and population status of many amphibians is relatively poor. A widely-used method for monitoring amphibians involves injecting captured individuals with unique combinations of colored visible implant elastomer (VIE). We compared VIE identification to a less-invasive method – computer-assisted photographic identification (photoID) – in endangered Jollyville Plateau salamanders (Eurycea tonkawae), a species with a known range limited to eight stream drainages in central Texas. We based photoID on the unique pigmentation patterns on the dorsal head region of 1215 individual salamanders using identification software Wild-ID. We compared the performance of photoID methods to VIEs using both ‘high-quality’ and ‘low-quality’ images, which were taken using two different camera types and technologies. For high-quality images, the photoID method had a false rejection rate of 0.76% compared to 1.90% for VIEs. Using a comparable dataset of lower-quality images, the false rejection rate was much higher (15.9%). Photo matching scores were negatively correlated with time between captures, suggesting that evolving natural marks could increase misidentification rates in longer term capture-recapture studies. Our study demonstrates the utility of large-scale capture-recapture using photo identification methods for Eurycea and other species with stable natural marks that can be reliably photographed.

Item Type:Articles
Additional Information:Work was primarily funded by the City of Austin, through staff time and purchase of materials. This includes the City of Austin Balcones Canyonland Preserve and Watershed Protection Department. The Texas Parks and Wildlife Department also provided staff assistance with this project. The funding agencies had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript (with the exception of the authors and acknowledged individuals).
Glasgow Author(s) Enlighten ID:Morrison, Dr Thomas
Authors: Hemmi, J. M., Bendik, N. F., Morrison, T. A., Gluesenkamp, A. G., Sanders, M. S., and O’Donnell, L. J.
College/School:College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
Journal Name:PLoS ONE
Publisher:Public Library of Science
ISSN (Online):1932-6203
Copyright Holders:Copyright © 2013 Bendik et al.
First Published:First published in PLoS ONE 8(3):e59424
Publisher Policy:Reproduced under a Creative Commons License

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