Data from: Escape distance in ground-nesting birds differs with individual level of camouflage

Camouflage is one of the most widespread antipredator strategies in the
animal kingdom, yet no animal can match its background perfectly in a
complex environment. Therefore, selection should favor individuals that
use information on how effective their camouflage is in their immediate
habitat when responding to an approaching threat. In a field study of
African ground-nesting birds (plovers, coursers, and nightjars), we tested
the hypothesis that individuals adaptively modulate their escape behavior
in relation to their degree of background matching. We used digital
imaging and models of predator vision to quantify differences in color,
luminance, and pattern between eggs and their background, as well as the
plumage of incubating adult nightjars. We found that plovers and coursers
showed greater escape distances when their eggs were a poorer pattern
match to the background. Nightjars sit on their eggs until a potential
threat is nearby, and, correspondingly, they showed greater escape
distances when the pattern and color match of the incubating adult's
plumage-rather than its eggs-was a poorer match to the background.
Finally, escape distances were shorter in the middle of the day,
suggesting that escape behavior is mediated by both camouflage and
thermoregulation.