A rabbit’s tail: conspicuous rump patch causes predator confusion

Prey animals display adaptive coloration which influences the predator-prey dynamic. Tail-flagging occurs when a prey animal makes itself highly conspicuous by raising its white tail whilst fleeing from a predator. This behaviour (seen in ungulates and cottontail rabbits) seems maladaptive because it appears to increase (not reduce) predator attention and pursuit. In terms of evolutionary function, there is no consensus on why tail-flagging occurs. Here we show that the function is likely based on predator confusion, due to perceptual distraction from the ‘blinking tail’ stimulus emerging from the rhythmic motion of the running prey. We tested 24 human ‘predators’ in a computer game where they were asked to repeatedly ‘follow’ a fleeing rabbit stimulus (represented by a 28mm circle moving across a scrolling grass-coloured field) by clicking one of three buttons – left, right, or unsure –after the rabbit makes a sudden lateral escape to the left or right (at unpredictable time intervals and direction). There were two conditions: (1) no-tail, where the rabbit-circle is the same colour as the scrolling field, and (2) with-tail, where the rabbit-circle is superimposed by a same-sized blinking white circle. We found that, for the blinking tail condition, correct replies are significantly lower and wrong/uncertain replies were significantly higher. Furthermore, we partitioned responses into ‘fast’ or ‘slow’ (above or below 500ms) and found that correct replies for the blinking tail condition were significantly higher only in slow responses. Our results demonstrate the adaptive advantage of tail-flagging because it impedes the predator’s lateral movement during pursuit.

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