Aegean wall lizards are among the most common preys of avian predators. Out in the open, the species appear helpless as sharp-eyed birds search for food. For these lizards, resting equates death, or is it?

Researchers from the University of Cambridge and University of Exeter found that these Greek lizards also camouflage itself. The species choose to rest on rocks with a similar color as its back so as to hide from bird attackers.

"Our key findings suggest that Aegean wall lizards (Podarcis erhardii) choose backgrounds that enhance matching for camouflage against avian predators in their natural microhabitats," the authors wrote.

Camouflage is most commonly associated with geckos and chameleons - lizard species that can naturally change its color for protection. Such mechanism is said to be enhanced by genetic adaptation, but the role of behavior in its effectiveness has not yet been explored.

Aegean wall lizards, found across Greek islands, may have the answer to this puzzle.

The researchers performed a visual modeling experiment to see how noticeable individual lizards would be to birds, depending on the background it chose to rest on.

The scientists found that individual lizards exhibited better color matching against its colored rock rest spots than other lizards' rock backgrounds. This is with respect to the view of abundant birds in site, such as raptors and crows.

Co-author Kate Marshall from Cambridge says the findings strongly suggest that individual behaviors have a vital effect in improving camouflage in diverse microhabitats.

The researchers also discovered that the ability of the lizards to camouflage itself increases in places where there are more predatory birds. Such finding further suggests that behavioral defense is more likely in play in more hazardous surroundings.

The mechanism behind how lizards "know" what rocks are best to rest onto is not yet clearly known. Marshall says it might be influenced by genetic control or the species may have learned it from other lizards or from experience.

The study was published in the journal Scientific Reports on Jan. 25.