Revealed by conspicuousness: distractive markings reduce camouflage

Stevens, Martin; Marshall, Kate L. A.; Troscianko, Jolyon; Finlay, Sive; Burnand, Dan; Chadwick, Stephen

doi:10.1093/beheco/ars156

Cited by 50 publications

(64 citation statements)

References 47 publications

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“…Although animal vision varies substantially between taxa, human performance in touch-screen experiments has been found to agree with behavioural data from non-humans [27]. Furthermore, spatial visual processing is thought to be similar between taxa [17], suggesting the results based on achromatic human performance should be good indicators of performance in many other vertebrate species.…”

Section: Methodsmentioning

confidence: 99%

“…We used tree-bark backgrounds as these are biologically relevant backgrounds for a wide range of camouflaged animals, and they exhibit a degree of background heterogeneity in contrast and spatial features. Artificial prey and tree-bark backgrounds such as these have been used extensively for testing camouflage theories because they capture the essence of camouflage patterns effectively without the need to find and take calibrated images of large numbers of camouflaged prey [4, 27, 28, 32]. These studies have also demonstrated that human and non-human visual systems respond similarly to these camouflage stimuli.…”

Section: Introductionmentioning

confidence: 99%

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Quantifying camouflage: how to predict detectability from appearance

2017

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BackgroundQuantifying the conspicuousness of objects against particular backgrounds is key to understanding the evolution and adaptive value of animal coloration, and in designing effective camouflage. Quantifying detectability can reveal how colour patterns affect survival, how animals’ appearances influence habitat preferences, and how receiver visual systems work. Advances in calibrated digital imaging are enabling the capture of objective visual information, but it remains unclear which methods are best for measuring detectability. Numerous descriptions and models of appearance have been used to infer the detectability of animals, but these models are rarely empirically validated or directly compared to one another. We compared the performance of human ‘predators’ to a bank of contemporary methods for quantifying the appearance of camouflaged prey. Background matching was assessed using several established methods, including sophisticated feature-based pattern analysis, granularity approaches and a range of luminance and contrast difference measures. Disruptive coloration is a further camouflage strategy where high contrast patterns disrupt they prey’s tell-tale outline, making it more difficult to detect. Disruptive camouflage has been studied intensely over the past decade, yet defining and measuring it have proven far more problematic. We assessed how well existing disruptive coloration measures predicted capture times. Additionally, we developed a new method for measuring edge disruption based on an understanding of sensory processing and the way in which false edges are thought to interfere with animal outlines.ResultsOur novel measure of disruptive coloration was the best predictor of capture times overall, highlighting the importance of false edges in concealment over and above pattern or luminance matching.ConclusionsThe efficacy of our new method for measuring disruptive camouflage together with its biological plausibility and computational efficiency represents a substantial advance in our understanding of the measurement, mechanism and definition of disruptive camouflage. Our study also provides the first test of the efficacy of many established methods for quantifying how conspicuous animals are against particular backgrounds. The validation of these methods opens up new lines of investigation surrounding the form and function of different types of camouflage, and may apply more broadly to the evolution of any visual signal.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0854-2) contains supplementary material, which is available to authorized users.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Quantifying camouflage: how to predict detectability from appearance

2017

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“…In siskins, black patches are related to dominance status (Senar and Camerino 1998) and cover a higher proportion of the overall body plumage in males than in females (Svensson 1992). Therefore, if they contribute to conspicuousness in some backgrounds and because of the contrast between dark and light plumage patches, their effect will be to increase the overall conspicuousness of males compared with females (Stevens et al 2013).…”

Section: Plumage Coloration Datamentioning

confidence: 99%

Plumage brightness, vigilance, escape potential, and predation risk in male and female Eurasian Siskins (Spinus spinus)

Pascual¹,

Senar²,

Domènech³

2014

The Auk

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“…One controllable method to study camouflage efficiency is to conduct detection experiments by presenting photographs of prey on paper to human predators (Gendron and Staddon, 1984;Todd, 2009). This allows for several iterations which are very difficult to conduct in the field, and it has been successfully used to study camouflage (Todd, 2009;Stevens et al, 2013), mimicry (Beatty et al, 2005), and aposematism (Summers and Clough, 2001). …”

Section: Introductionmentioning

confidence: 99%