Disruptive and cryptic coloration

Abstract

Camouflage may be achieved in three ways: crypsis, disruptive coloration and masquerade (Endler 1981). Cryptic prey resemble random samples of the visual background (Endler 1978(Endler , 1981(Endler , 1984, minimizing their signal/noise ratio (S/N). Disruptively coloured prey contain some highly conspicuous as well as cryptic pattern elements. The conspicuous elements distract the predator's attention and break up the body outline, making detection of the prey difficult (Thayer 1909;Cott 1940;. In masquerade, the prey is detected as distinct from the visual background but not recognized as edible (Endler 1981), for example by resembling a leaf (Thayer 1909). The two ways of avoiding detection, crypsis and disruptive coloration, appear contradictory (Merilaita & Lind 2005), because crypsis relies on minimizing the S/N, while disruptive coloration relies on keeping S/N high.This issue of Proceedings B contains two elegant papers on the interaction between disruptive coloration and crypsis (Schaefer & Stobbe 2006;). Following Cuthill et al. (2005, these authors constructed artificial prey with pattern elements that stimulated bird eyes in known ways (allowing visual contrast predictions), attached a mealworm to each moth-like stimulus for a reward, and presented these prey to wild birds by attaching them to tree trunks and recording disappearance. The stimuli consisted of some patches that were similar to and other patches that contrasted with the visual background. In disruptive ('edge') patterns, contrasting patches cut across the edges of the 'wings', while in the non-disruptive ('inside') patterns, the contrasting patches were away from the edges of the wings. Like Cuthill et al. (2005), the two new papers found that the disruptive pattern resulted in higher 'survivorship' (significantly lower rates of removal by the birds) than the inside pattern. These new papers go further in examining the joint effects of contrast and outline disruption on fitness.Schaefer & Stobbe (2006) presented the prey against two different visual backgrounds: birch and oak bark with moss. In the first two experiments, the brown and pink colours of the stimuli were similar to a real moth, while in the third a novel colour (blue) was used. Schaefer & Stobbe (2006) predicted that the advantage of disruptive patterns would be greater when disruptive patches had higher contrast, and that disruptive contrast with the visual background increases fitness even if it decreases crypsis. On birch, the cryptic non-disruptive form did worse than the others. On oak, the edge forms and the cryptic (brown) inside form did equally well but better than the more conspicuous pink inside form. This suggests that on some backgrounds the joint effects of disruption

Cephalopod dynamic camouflage: bridging the continuum between background matching and disruptive coloration

“…For over a century, astute biologists have suggested a distinction between the tactics of background matching and disruptive coloration. Excellent recent studies (including others in this volume) have begun to unravel their interrelationships (Merilaita 1998;Cuthill et al 2005Cuthill et al , 2006Merilaita & Lind 2005;Endler 2006;Schaefer & Stobbe 2006;Stevens et al 2006a,b;Fraser et al 2007;Stevens 2007;Stobbe & Schaefer 2008). Nonetheless, the concept that each is a separate tactic by which to fool visual predators is still controversial.…”

Empirical tests of the role of disruptive coloration in reducing detectability

“…Future work might address whether disruptive patterning allows its carrier to exploit a greater range of habitats than an organism with only background matching, and whether search images for disruptively patterned prey can be developed by predators. A computer-based system such as the one employed here not only enables close control over the foraging environment, but it also potentially allows camouflage solutions to evolve when subjected to selection (see also Bond & Kamil 2002, 2006Sherratt et al 2007). If disruptive pattern solutions were introduced to this general approach, then we would have a unique set of tools for designing and identifying effective camouflage strategies in a wide range of contexts.…”

“…First, Cuthill et al used colours that effectively matched their backgrounds, so the adaptive value of disruptive coloration is hard to evaluate completely independently of background matching. This limitation has recently been addressed by Merilaita & Lind (2005), Schaefer & Stobbe (2006) and , but, nevertheless, more work needs to be done (Endler 2006). For example, in generating disruptively patterned nonbackground-matching moths, varied the lighter colour to create a non-matching treatment, but not the colour of the darker disruptive marks themselves.…”

Enhancement of chromatic contrast increases predation risk for striped butterflies

“…Field experiments on disruptive coloration of artificial moths also suggest that colour contrasts may play a crucial role in achieving protection (Schaefer & Stobbe 2006). However, the definite relevance of chromatic cues for the effectiveness of disruptive coloration is yet to be investigated (Endler 2006;.…”

“…However, disruptive coloration relies on contrasting patterns that impede recognition of animals as potential prey objects. Although researchers have made progress in demonstrating the effectiveness of disruptive coloration (Merilaita 1998;Cuthill et al 2005;Merilaita & Lind 2005;Schaefer & Stobbe 2006;Fraser et al 2007), many aspects of how disruptive patterns deceive the visual and cognitive abilities of predators remain as yet unclear (Sherratt et al 2005;Endler 2006).…”