Camouflage in lichen moths: Field predation experiments and avian vision modelling demonstrate the importance of wing pattern elements and background for survival

Abstract

Background matching is perhaps the most ubiquitous form of defensive camouflage in the animal kingdom, an adaptive strategy that relies on the visual resemblance between a prey organism and its background to promote concealment from predators. The importance of background matching has been acknowledged for over a century, yet despite its renown and apparent pervasiveness, few studies exist that have objectively quantified its occurrence and tested the functional significance of background matching in a specific animal study system. The North Island lichen moth Declana atronivea presents a fascinating system to investigate such anti‐predator coloration. This species possesses high contrast black and white forewings that appear to resemble lichen. Here we assessed the contribution of background matching to the antipredator defence of D. atronivea using field predation experiments with realistic models. We found that D. atronivea coloration confers a significant survival advantage against native avian predators when on lichen backgrounds compared to bark backgrounds, with an intermediate level of predation occurring when models were near, but not on lichen. This suggests that D. atronivea wing patterns are an adaptation for background matching. We subsequently used calibrated digital photography, avian vision modelling and image analysis techniques to objectively quantify the degree of background matching exhibited by D. atronivea and assessed the contribution of different visual elements (colour, luminance and pattern) to camouflage in this species. Only the pattern elements of D. atronivea presented a close match to that of the lichen backgrounds, with both chromatic and achromatic cues found to be poor predictors of background matching in this species. This study is one of the first to integrate vision modelling, quantitative image analysis and field predation experiments using realistic models to objectively quantify the level and functional significance of background matching in a real species, and presents an ideal system for further investigating the interrelation between multiple mechanisms of camouflage.

Enclosure Background Preferences Differ between Sexes and Color Morphs in the Gouldian Finch

“…The study specifically tested whether Gouldian finches prefer complex over simple backgrounds. While background matching with respect to colors is an important aspect of camouflage [ 6 , 8 , 19 , 20 , 21 ], we did not try to match background colors with plumage colors due to the potentially different perception of colors by the birds (tetra-chromatic vision [ 48 ]). However, the complexity of backgrounds alone has been shown to reduce predation [ 40 ].…”

“…One of the main anti-predator strategies is camouflage, with animals blending into their environment. As most predators use vision to detect prey with a preference for color cues [ 1 , 2 ] (but see [ 3 ]), animals’ coloration has evolved to match their background [ 4 , 5 , 6 , 7 , 8 ]. However, in captive environments, there is often a mismatch between an animal’s color and its environment, which can be perceived by the animal as being vulnerable and under stress.…”

“…Background matching is one of the most common camouflage strategies [ 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. Camouflage is achieved by matching the average background [ 11 , 15 , 16 ] or specific aspects of the background (e.g., leaves) [ 17 ] and exploiting the perception and cognitive mechanisms of predators [ 18 ].…”

“…Camouflage is achieved by matching the average background [ 11 , 15 , 16 ] or specific aspects of the background (e.g., leaves) [ 17 ] and exploiting the perception and cognitive mechanisms of predators [ 18 ]. Reducing the contrast against the background has been shown to decrease detectability and hence predation [ 6 , 8 , 19 , 20 , 21 ]. It can affect population densities with higher densities in areas of better camouflage efficiency [ 16 ], support species divergence with recently diverged species showing a close match to the environment [ 20 ], and positively affect the invasion success of new habitats with better background matching.…”

Genetic Basis and Evolutionary Forces of Sexually Dimorphic Color Variation in a Toad-Headed Agamid Lizard

“…The visual modeling is an objective method for color conspicuousness analysis because it simultaneously considers the senders’ spectral reflectance curve, the spectral sensitivities of cone pigments for the UV (UVS), short (SWS), medium (MWS), and long wavelengths (LWS) for the receivers’ visual system, and environmental irradiance measures ( Endler and Mielke 2005 ). This approach has been widely used in camouflage research ( Price et al 2019 ; Mark et al 2022 ; Whiting et al 2022 ). In our visual modeling, we used the spectral reflectance curve of 209 GN individuals (90 males and 119 females).…”