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Published (Version of Record)CC BY V4.0, Open Access
Journal article
The role of pictorial cues and contrast for camouflage
Evolutionary ecology, Vol.37, pp.909-925
2023
Abstract
Shadows that are produced across the surface of an object (self-shadows) are potentially an important source of information for visual systems. Animal patterns may exploit this principle for camouflage, using pictorial cues to produce false depth information that manipulates the viewer’s detection/recognition processes. However, pictorial cues could also facilitate camouflage by matching the contrast (e.g. due to shadows) of 3D backgrounds. Aside from studies of countershading (patterning that may conceal depth information), the role of self-shadows in camouflage patterns remains unclear. Here we investigated whether pictorial cues (self-shadows) increase the survival probability of moth-like prey presented to free-living wild bird predators relative to targets without these cues. We manipulated the presence of self-shadows by adjusting the illumination conditions to produce patterned targets under directional lighting (lit from above or from below; self-shadows present) or diffuse lighting (no self-shadows). We used non-patterned targets (uniform colour) as controls. We manipulated the direction of illumination because it has been linked with depth perception in birds; objects lit from above may appear convex while those lit from below can appear concave. As shadows influence contrast, which also determines detectability, we photographed the targets in situ over the observation period, allowing us to evaluate the effect of visual metrics on survival. We found some evidence that patterned targets without self-shadows had a lower probability of survival than patterned targets with self-shadows and targets with uniform colour. Surprisingly, none of the visual metrics explained variation in survival probability. However, predators increased their foraging efficiency over time, suggesting that predator learning may have overridden the benefits afforded by camouflaging coloration.
Details
- Title
- The role of pictorial cues and contrast for camouflage
- Authors/Creators
- Jennifer L. Kelley - The University of Western AustraliaAnna-Lee Jessop - Murdoch UniversityLaura A. Kelley - University of ExeterJolyon Troscianko - University of Exeter
- Publication Details
- Evolutionary ecology, Vol.37, pp.909-925
- Publisher
- Springer
- Identifiers
- 991005609668207891
- Copyright
- © 2023 The Author(s)
- Murdoch Affiliation
- School of Mathematics, Statistics, Chemistry and Physics
- Language
- English
- Resource Type
- Journal article
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- Collaboration types
- Domestic collaboration
- International collaboration
- Citation topics
- 3 Agriculture, Environment & Ecology
- 3.35 Zoology & Animal Ecology
- 3.35.434 Sexual Selection
- Web Of Science research areas
- Ecology
- Evolutionary Biology
- Genetics & Heredity
- ESI research areas
- Environment/Ecology