Dappled light disrupts prey detection by masking movement. (September 2019) - Matchette, Samuel R.
Abstract : Prey and ambush predators that rely on concealment face a major constraint: motion breaks their camouflage. However, dappled light is a common feature of sunny, vegetated habitats and can, when conditions are windy, become a source of dynamic visual noise. We tested the idea that this could mask movement, reducing the risk of detection. Newly hatched domestic fowl chicks, Gallus gallus domesticus, a proxy for wild forest-floor birds, were trained to peck moving, on-screen prey presented among two sources of dynamic dappled light: computer-simulated and that created with a mirror ball. Dynamic dapple, however produced, increased the chick's latency to both fixate and peck the prey. Furthermore, we show that dynamic visual noise masks motion in a way that static visual noise does not. This reduction in foraging efficiency should, we predict, have significant consequences for an organism's choice of habitat (as prey), foraging area (as predator) and its pattern of movement within a habitat. Highlights: Dappled light is a common source of visual noise within natural environments. Visual noise reduces the signal-to-noise ratio and can mask conspicuous signals. Dynamic dappled light masks movement of simulated prey for domestic fowl chicks. Masking occurred with both sources of dynamic dappled light (screen and mirror ball).