Deimatism: a neglected component of antipredator defence

Abstract

Deimatic or 'startle' displays cause a receiver to recoil reflexively in response to a sudden change in sensory input. Deimatism is sometimes implicitly treated as a form of aposematism (unprofitability associated with a signal). However, the fundamental difference is, in order to provide protection, deimatism does not require a predator to have any learned or innate aversion. Instead, deimatism can confer a survival advantage by exploiting existing neural mechanisms in a way that releases a reflexive response in the predator. We discuss the differences among deimatism, aposematism, and forms of mimicry, and their ecological and evolutionary implications. We highlight outstanding questions critical to progress in understanding deimatism.

Does rattling deter? The case of domestic dogs

“…As mentioned above, Swaisgood et al (1999) reported that the immediate reaction of foraging ground squirrels to rattle playbacks was to jump away from the speaker, but they often returned to resume eating, perhaps after reassessing the threat. Carefully constructed experiments that precisely examine the immediate reaction of individuals when first hearing a rattling sound are needed in order to tease aposematism and deimatism apart (Holmes, Delferriere, Rowe, Troscianko, & Skelhorn, 2018;Skelhorn, Holmes, & Rowe, 2016;Umbers et al, 2017).…”

Resemblance of a model species and its mimic: Response to Bury and Cichoń

“…, ; Umbers et al. ). It is important to keep in mind that most prey species are preyed on by several different types of predators, and even the most venomous species have their enemies (Mappes et al.…”

“…Many aposematic species rely on crypsis and reveal their warning signals after detection (Barnett & Cuthill 2014;Barnett et al 2016Barnett et al , 2017Umbers et al 2017). It is important to keep in mind that most prey species are preyed on by several different types of predators, and even the most venomous species have their enemies (Mappes et al 2005).…”

Two Models of Predator Decision Making Under Uncertainty

“…Additionally, the startle display may exist as a component of a portfolio of successive defences (Kang et al 2016;Bateman et al 2014;Britton et al 2007), where being suddenly revealed allows it to act as a backup to another defence. A startle display is a low cost defence that can be deployed early following encounter, and it is particularly suitable as a backup defence to crypsis (Umbers et al 2017).…”

“…Startle displays (also called deimatic displays, from the Greek δϵιµατóω, "I frighten" ;Maldonado 1970;Liddell and Scott 1940) are a form of anti-predator defence in which prey produce a sudden, conspicuous signal upon being approached by a predator (usually some sort of radical change in phenotype), which causes the predator to delay or break off attacking (Ruxton et al 2018;Umbers et al 2017).…”