Non-random perch selection by cryptic lizards, Amphibolurus muricatus

Abstract

Many animals make use of camouflage to avoid or reduce visual detection by predators or prey species. Among the diverse forms of animal camouflage, background matching—where an individual’s appearance helps it blend into the visual backdrop of a scene—is commonly observed as a major function of cryptic species’ patterning and coloration. While some animals can rapidly modify their pattern to match their surroundings and better avoid detection, most possess static patterns or coloration and cannot quickly adjust to suit the visual environment. We expect such animals to consider the cryptic suitability of a background they choose to occupy, ideally selecting one with features suitable relative to their own markings, thereby maximizing concealment. This relationship is complicated by the potential range of different substrates typically available in any one habitat, as conspicuousness may vary considerably when viewed against the different background options available. In the present study, we tested some of these assumptions, investigating whether cryptic lizards, Amphibolurus muricatus (jacky dragons), utilized perch options with features complementary to their dorsal camouflage patterns more so than unsuitable perches. In two experiments, lizards were provided with perch options differing in coloration and cover availability and pattern, respectively. Individuals spent significantly more time using perches with cover available in the first experiment, and those with more complex patterns in the second. These findings suggest cryptic lizards may be selecting basking sites in a non-random fashion with respect to the visual environment in order to enhance camouflage success and that cover may be more important to perch selection than previously thought. SIGNIFICANCE STATEMENT: Among animals that employ visual camouflage as a primary survival strategy, differences in conspicuousness caused by being viewed upon the various suitable and unsuitable backgrounds available in a habitat have the potential to drastically affect prey capture and predation, and hence survival. With respect to this, cryptic animals should prefer to occupy substrates that are relevant to their own patterns and offer better concealment. Research in this behavioral maintenance of camouflage has focused on spectral properties of camouflage and substrates, but studies on fine-scale pattern and behavior in camouflage are under-represented. In captive perch choice experiments, we found that male jacky dragons (Amphibolurus muricatus) preferred perches with more complex patterns and those with plant cover available nearby. This research highlights the important role of behavior in supporting camouflage strategies and some of the considerations made when cryptic individuals choose substrates.