However, a factor extrinsic to the camouflaged object also affects its concealment: background complexity. Camouflage is the most widespread means of achieving concealment ‘in plain sight’, arguably the most critical factor being the similarity of the object's colour and pattern to that of its immediate background. Remaining undetected is frequently important for a number of reasons, including predator–prey interactions, avoiding social harassment and seeking sneak mating opportunities. Our results suggest that poorer camouflage can be mitigated by more complex backgrounds, with implications for both camouflage evolution and habitat preferences. Higher background orientation clutter (edges with varying orientation) reduced the detectability of all but the poorest background-matching camouflaged treatments higher background luminance clutter (varying achromatic lightness) reduced average mortality for all treatments. The latter was quantified using low-level vision metrics of feature congestion (or ‘visual clutter’) adapted for bird vision. Do habitats of high visual complexity provide concealment to even relatively poorly camouflaged animals? Using artificial prey which differed in their degrees of background matching to tree bark, we were able to determine their survival, under bird predation, with respect to the natural complexity of the background.
This has been experimentally demonstrated for both artificially patterned backgrounds in the laboratory and natural backgrounds in the wild, but only for targets that already match the background well. However, an animal's appearance is not the only factor affecting conspicuousness: background complexity also alters detectability. Avoiding detection through camouflage is often key to survival.
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