title: Zebra Stripes through the Eyes of Their Predators, Zebras, and Humans.
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.
authors.affiliation: Department of Anthropology, Washington University in St. Louis, St. Louis, Missouri, 63130, United States of America.|Departments of Anthropology & Archaeology and Cell Biology & Anatomy University of Calgary, Calgary, Alberta T2N 1N4, Canada.
authors.forename: Amanda D
authors.initials: AD
authors.lastname: Melin
authors.affiliation: Departments of Psychology and Surgery (Ophthalmology), University of Calgary, Calgary, Alberta T2N 1N4, Canada.
authors.forename: Donald W
authors.initials: DW
authors.lastname: Kline
authors.affiliation: Department of Human Science, Faculty of Design, Kyushu University, Fukuoka, 815-8540, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Hiramatsu
authors.affiliation: Department of Wildlife, Fish and Conservation Biology, University of California Davis, Davis, California 95616, United States of America.
authors.forename: Tim
authors.initials: T
authors.lastname: Caro
mesh_terms: D000818:Animals; D003116:Color; D003118:Color Perception / Q000502:physiology*; D018397:Equidae / Q000502:physiology*; D065928:Forests; D006801:Humans; D045968:Hyaenidae; D008045:Lions; D010781:Photography; D010858:Pigmentation; D011235:Predatory Behavior; D014796:Visual Perception