Enhancement of chromatic contrast increases predation risk for striped butterflies

Abstract

Many prey species have evolved defensive colour patterns to avoid attacks. One type of camouflage, disruptive coloration, relies on contrasting patterns that hinder predators' ability to recognize an object. While high contrasts are used to facilitate detection in many visual communication systems, they are thought to provide misleading information about prey appearance in disruptive patterns. A fundamental tenet in disruptive coloration theory is the principle of 'maximum disruptive contrast', i.e. disruptive patterns are more effective when higher contrasts are involved. We tested this principle in highly contrasting stripes that have often been described as disruptive patterns. Varying the strength of chromatic contrast between stripes and adjacent pattern elements in artificial butterflies, we found a strong negative correlation between survival probability and chromatic contrast strength. We conclude that too high a contrast leads to increased conspicuousness rather than to effective camouflage. However, artificial butterflies that sported contrasts similar to those of the model species Limenitis camilla survived equally well as background-matching butterflies without these stripes. Contrasting stripes do thus not necessarily increase predation rates. This result may provide new insights into the design and characteristics of a range of colour patterns such as sexual, mimetic and aposematic signals.

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

“…Disruptive coloration is a more difficult concept to grasp and measure, and therefore is a subject of considerable scepticism. The emergent trend from recent studies (which was hinted at by Cott and others) is that disruptive coloration is indeed a visual tactic of camouflage, but that some components of disruptive patterns appear to enhance background matching when tested with bird or human observers (Cuthill et al 2005;Schaefer & Stobbe 2006;Stevens et al 2006a;Fraser et al 2007;Stobbe & Schaefer 2008). In cephalopods, we have described disruptive coloration but without experimental proof that the patterns we observe are functioning by the disruptive tactic (e.g.…”

“…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.…”

The benefit of being a social butterfly: communal roosting deters predation

“…None of the 80 sites were used twice in the study because predator forgetting time varies between bird species, and is affected by prey conspicuousness and distastefulness [59][60][61], both difficult to measure for this project. A butterfly was considered attacked if damage to the abdomen and wings appeared in the form of beak marks and/or large indentations in the abdomen (figure 1c,d; see also [62,63]). Small chew-like marks, probably from mandibular insects such as grasshoppers, were not considered in the data analyses.…”

Warning coloration can be disruptive: aposematic marginal wing patterning in the wood tiger moth

“…2005, 2006; Merilaita and Lind 2005; Schaefer and Stobbe 2006; Stevens et al. 2006; Stobbe and Schaefer 2008) and human predators (Fraser et al. 2007).…”

“…However, some evidence indicates that the survival of individuals with disruptive color patterns characterized by extremely high contrast between adjacent color pattern elements (i.e., “maximum disruptive contrast”; Stevens and Merilaita 2009b) is worse than that of individuals with less contrasting patterns, because the contrast of the pattern elements with background elements is also high (Fraser et al. 2007; Stobbe and Schaefer 2008; Troscianko et al. 2013).…”