Zebra Stripes through the Eyes of Their Predators, Zebras, and Humans
Amanda D. Melin , Donald W. Kline, Chihiro Hiramatsu, Tim Caro
Published: January 22, 2016DOI: 10.1371/journal.pone.0145679
Abstract
The century-old idea that stripes make zebras cryptic to large carnivores has never been examined systematically. We evaluated this hypothesis by passing digital images of zebras through species-specific spatial and colour filters to simulate their appearance for the visual systems of zebras’ primary predators and zebras themselves. We also measured stripe widths and luminance contrast to estimate the maximum distances from which lions, spotted hyaenas, and zebras can resolve stripes. We found that beyond ca. 50 m (daylight) and 30 m (twilight) zebra stripes are difficult for the estimated visual systems of large carnivores to resolve, but not humans. On moonless nights, stripes are difficult for all species to resolve beyond ca. 9 m. In open treeless habitats where zebras spend most time, zebras are as clearly identified by the lion visual system as are similar-sized ungulates, suggesting that stripes cannot confer crypsis by disrupting the zebra’s outline. Stripes confer a minor advantage over solid pelage in masking body shape in woodlands, but the effect is stronger for humans than for predators. Zebras appear to be less able than humans to resolve stripes although they are better than their chief predators. In conclusion, compared to the uniform pelage of other sympatric herbivores it appears highly unlikely that stripes are a form of anti-predator camouflage.
Citation: Melin AD, Kline DW, Hiramatsu C, Caro T (2016) Zebra Stripes through the Eyes of Their Predators, Zebras, and Humans. PLoS ONE 11(1): e0145679. doi:10.1371/journal.pone.0145679
Editor: Daniel Osorio, University of Sussex, UNITED KINGDOM
Received: September 15, 2015; Accepted: December 7, 2015; Published: January 22, 2016
Copyright: © 2016 Melin et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: Most data is in the paper and Supporting Information files; S3 Dataset is hosted at the Harvard Dataverse, http://dx.doi.org/10.7910/DVN/OHWWNR.
Funding: Funding was provided by the Wenner Gren Foundation (http://www.wennergren.org/) to ADM, the National Sciences and Engineering Research Council of Canada to ADM (http://www.nserc-crsng.gc.ca/), the National Geographic Society (http://www.nationalgeographic.com/) to TC and University of California Davis to TC. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
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