Deception by imitation
A neat behavioural demonstration of predator-masquerade from John Skelhorn has just arrived. It’s unsurprising that it works for predators as well as prey, and I didn’t realise it hadn’t actually been tested before, but it is an elegant study of a striking phenomenon.
Understanding how natural selection has shaped animals’ visual appearance to aid predator avoidance and prey capture has been an ongoing challenge since the conception of evolutionary theory [1,2] . Masquerade — animals resembling inedible objects common in the local environment (e.g. twigs, leaves, stones) — is one of a handful of strategies that has been suggested to serve both protective and aggressive functions (i.e. to work for both prey and predators)  . There is now good evidence for protective masquerade: predators detect masquerading prey but ignore them because they mistake them for the inedible objects they resemble  . However, there is no direct evidence that predators can benefit from aggressive masquerade [3,5] . Here, I tested the idea that prey detect masquerading predators but mistake them for the innocuous items that they resemble, making them less wary and easier for predators to catch. Because prey can only mistake masquerading predators for the objects they resemble if they have previous experience of those items, I manipulated house crickets’ (Acheta domesticus) experience with dead leaves, before placing them in tanks with dead-leaf-resembling Ghost mantises (Phyllocrania paradoxa). I found that mantises given crickets with experience of unmanipulated dead leaves caught crickets faster and after fewer attempts than mantises given crickets without experience of dead leaves, or crickets with experience of manipulated dead leaves that no longer resembled mantises. These findings demonstrate that predators can indeed benefit from aggressive masquerade.