Chromaticity in the UV/blue range facilitates the search for achromatically background-matching prey in birds

Stobbe, Nina; Dimitrova, Marina; Merilaita, Sami; Schaefer, H. Martin

doi:10.1098/rstb.2008.0248

Cited by 19 publications

(14 citation statements)

References 49 publications

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“…We found that achromatic contrast of the ground predator was higher in sunlit than in shaded patches, but the ability of individuals to make use of an increase in the predator brightness for detection may have actually been constrained by the greater light intensity leading to the glare effects. Stobbe et al 2009;Lindstedt et al 2011). 2).…”

Section: Discussionmentioning

confidence: 99%

Predator Detection is Limited in Microhabitats with High Light Intensity: An Experiment with Brown‐Headed Cowbirds

et al. 2012

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Variations in ambient light conditions across different microhabitats can modify the detectability of predators and prey. Prey have been shown to be more visible in sunlit than in shaded patches, leading to higher predation risk and more investment in vigilance (predation risk hypothesis). Additionally, prey have been hypothesized to take longer to detect predators in sunlit compared to shaded patches because of the excess of sunlight causing glare effects (disability glare hypothesis). We tested the predictions of these two non‐mutually exclusive hypotheses in a seminatural experiment with brown‐headed cowbirds by measuring vigilance behavior and detection of a ground predator in patches under the shade of vegetation and in the open. Light intensity and achromatic contrast were higher in the sunlit patches, which could enhance glare effects, but chromatic contrast was higher in the shaded patches. Brown‐headed cowbirds took longer to show alert reactions to and flee from a ground predator in sunlit compared to shaded patches. However, the two parameters associated with perceived predation risk (vigilance prior to the predator exposure and time to resume foraging after the attack) did not differ between sunlit and shaded patches. Our findings support to a greater extent the disability glare hypothesis than the predation risk hypothesis. Overall, ambient light conditions can affect two critical components of behavioral predator–prey interactions in terrestrial habitats: detection of and escape from predators. The effects of disability glare are expected to be more pronounced in bird species with wider visual fields or without sun‐shading structures; however, species may compensate through various behaviors (e.g. avoidance of sunlit patches and changes in head orientation).

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Section: Discussionmentioning

confidence: 99%

Predator Detection is Limited in Microhabitats with High Light Intensity: An Experiment with Brown‐Headed Cowbirds

et al. 2012

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“…Webster et al (2009) investigate the camouflage and resting orientation of wild moths, using detection experiments with human 'predators', showing that the coloration and resting position of the moths produces effective camouflage. Stobbe et al (2009) present the findings of laboratory predation experiments with avian predators and artificial prey, to investigate the relative importance of colour and luminance in effective camouflage. Rowland (2009) reviews previous work and presents new data to investigate the function of countershading in producing camouflage, with Tankus & Yeshurun (2009) adopting a computer vision approach to illustrate how detection of cylindrical objects may work in predators, and how the countershading of prey animals may inhibit this detection process.…”

Section: Contributions To the Theme Issuementioning

confidence: 99%

Animal camouflage: current issues and new perspectives

Stevens

Merilaita

2008

Phil. Trans. R. Soc. B

Self Cite

667

632

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The study of camouflage has a long history in biology, and the numerous ways of concealment and disguise found in the animal kingdom provided Darwin and Wallace with important examples for illustrating and defending their ideas of natural selection and adaptation. Thus, various forms of camouflage have become classical examples of evolution. In a broader sense, camouflage has been adopted by humans, most notably by the military and hunters, but it has also influenced other parts of society, for example, arts, popular culture and design.Animals use camouflage to make detection or recognition more difficult, with most examples associated with visual camouflage involving body coloration. However, in addition to coloration, camouflage may make use of morphological structures or material found in the environment, and may even act against senses other than vision (Ruxton 2009). In nature, some of the most striking examples of adaptation can be found with respect to avoiding being detected or recognized, with the strategies employed diverse, and sometimes extraordinary. Such strategies can include using markings to match the colour and pattern of the background, as in various moths (e.g. Kettlewell 1955), and to break up the appearance of the body, as in some marine isopods (Merilaita 1998). Camouflage is a technique especially useful if the animal can change colour to match the background on which it is found, such as can some cephalopods (Hanlon & Messenger 1988) and chameleons (Stuart-Fox et al. 2008). Further remarkable examples include insects bearing an uncanny resemblance to bird droppings (Hebert 1974) or fish resembling fallen leaves on a stream bed (Sazima et al. 2006), to even making the body effectively transparent, as occurs in a range of, in particular, aquatic species (Johnsen 2001;Carvalho et al. 2006). Examples such as

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“…The duration of prey search on the matching background was significantly longer, but the search for more chromatic prey on the same background was easier. The birds evidently used the combination of achromatic and chromatic cues for the successful search for prey (Stobbe et al, 2009). …”

Section: Food Detection By Other Birdsmentioning

confidence: 99%

Ultraviolet (UV) light perception by birds: a review

Rajchard¹

2009

Vet. Med.

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ABSTRACT:The ability to perceive the near ultraviolet part of the light spectrum (the wavelength 320-400 nm) has been detected in many bird species. This ability is an important bird sense. The ecological importance of UV perception has been studied mainly in the context of intra-and inter-sexual signalling, common species communication and also in foraging. Some birds of prey use UV reflectance in their feeding strategy: e.g., the kestrel (Falco tinnunculus), but also other birds of prey are able to recognize the presence of voles by perceiving the UV reflectance of their scent urine marks. The ability to detect the presence of prey is a common feature of birds with analogous feeding spectra in taxonomically distinct species. UV perception and its use in foraging have also been proved in predominantly herbivorous bird species. This ability is possessed both by bird species living in northern habitats and others living in tropical forests. The signalling and communication role of the UV perception is very important. The plumage of many bird species shows specific colour features -e.g., sexually different regions in plumage coloration unnoticed by the human eye. Also other body parts can have similar features -e.g., supra-orbital combs in the red grouse (Lagopus lagopus scoticus). All these characteristics are important primarily in the mate-choice decision. Birds apparently also use their ability of UV perception for recognition of their own eggs. Some bird species are able to modify plumage UV reflectance by uropygial secretions. The knowledge of all specific aspects of bird physiology can significantly help both breeders of various bird species and facilitate effective veterinary care.

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Chromaticity in the UV/blue range facilitates the search for achromatically background-matching prey in birds

Cited by 19 publications

References 49 publications

Predator Detection is Limited in Microhabitats with High Light Intensity: An Experiment with Brown‐Headed Cowbirds

Predator Detection is Limited in Microhabitats with High Light Intensity: An Experiment with Brown‐Headed Cowbirds

Animal camouflage: current issues and new perspectives

Ultraviolet (UV) light perception by birds: a review

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