The anti-predation benefit of flash displays is related to the distance at which the prey initiates its escape

Flash behaviour is widespread in the animal kingdom and describes the exposure of a hidden conspicuous signal by an otherwise cryptic individual as it is fleeing from predators. Recent studies have demonstrated that the signal can enhance survivorship by leading pursuing predators into believing the flasher will also be conspicuous at rest.  Naturally, this illusion will work best if potential predators are ignorant of the flasher's resting appearance. One way in which this could be achieved is by the prey fleeing when the predator is far away. To test this hypothesis, we compared the survival of flashing and non-flashing computer-generated prey with different flight initiation distances (FIDs) using humans as model predators. This experiment found that flash displays confer a significant survivorship advantage only to those prey with a sufficiently long FID that the predator has little opportunity to view them at rest. A complementary phylogenetic analysis of Australian bird species supports these results: after controlling for body size, species with putative flashing signals had longer FIDs than those without. Species with putative flashing signals also tended to be larger, as demonstrated in other taxa. The anti-predation benefit of flash displays is therefore related to the nature of escape behaviour.