Motion camouflage

Motion camouflage is a dynamic type of camouflage by which an attacker can approach a target while appearing to remain stationary from the perspective of the target. The attacker chooses its flight path so as to remain on the line between the target and some landmark point. It therefore does not move from the landmark point from the target's perspective. The only visible evidence that the attacker is moving is its looming, the change in size as the attacker approaches.

First discovered in hoverflies in 1995, motion camouflage has been demonstrated in another insect order, dragonflies, as well as in two groups of vertebrates, falcons and echolocating bats. It is possible that cuttlefish (cephalopod molluscs) are also using the strategy.

Since bats hunting at night cannot be using the strategy for camouflage, it has been named, describing its mechanism, as constant absolute target direction. This is an efficient homing strategy, and it has been suggested that anti-aircraft missiles could benefit from similar techniques.

Many animals are highly sensitive to motion; for example, frogs readily detect small moving dark spots but ignore stationary ones. Therefore, motion signals can be used to defeat camouflage, raising the question of how motion itself could be camouflaged. Several mechanisms are possible:

Motion camouflage was discovered in 1995 by M. V. Srinivasan and M. Davey while they were studying mating behaviour in hoverflies. The male hoverfly appeared to be using the tracking technique to approach prospective mates.

Motion camouflage has been observed in high-speed territorial battles between dragonflies, where males of the Australian emperor dragonfly, Hemianax papuensis (Aeshnidae) were seen to choose their flight paths to appear stationary to their rivals. Researchers found that 6 of 15 encounters involved motion camouflage.

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Wikipedia