The anti-predation benefit of flash displays is related to the distance at which the prey initiates its escape

Abstract

Flash behaviour is widespread in the animal kingdom and describes the exposure of a hidden conspicuous signal as an animal flees from predators. Recent studies have demonstrated that the signal can enhance survivorship by leading pursuing predators into assuming the flasher is also conspicuous at rest. Naturally, this illusion will work best if potential predators are ignorant of the flasher's resting appearance, which could be achieved if the prey flees while the predator is relatively far away. To test this hypothesis, we compared the survival of flashing and non-flashing computer-generated prey with different flight initiation distances (FIDs) using humans as model predators. This experiment found that flash displays confer a survivorship advantage only to those prey with a long FID. A complementary phylogenetic analysis of Australian bird species supports these results: after controlling for body size, species with putative flashing signals had longer FIDs than those without. Species with putative flashing signals also tended to be larger, as demonstrated in other taxa. The anti-predation benefit of flash displays is therefore related to the nature of escape behaviour. Since birds with hidden signals tend to flee at a distance, the flash display here is unlikely to function by startling would-be predators.

Evolutionary transitions from camouflage to aposematism: Hidden signals play a pivotal role

“…S10 for the results when the binary classification was used). Thus, macroevolutionary studies on animal coloration should take into account these underappreciated hidden signals, which are both common and widespread across the animal kingdom ( 13 , 43 , 44 ), to advance our understanding of the evolution of antipredator defenses. Indeed, many animal taxa such as snakes, fishes, and a variety of arthropods (see fig.…”

Antipredator defences in motion: animals reduce predation risks by concealing or misleading motion signals

“…Teasing apart the evolutionary drivers shaping warning signals is an important next step to understand the importance of flash (and deimatic) behaviour as an antipredator defence. In amphibians, the evolution of cryptic to aposematic colours involves hidden colour signals as an intermediate stage (Loeffler-Henry, Kang & Sherratt, 2023).…”

“…The predator may assume that the prey has a conspicuous appearance and would continue the search for the conspicuous features of the prey when the signals are hidden (Cott, 1940; Edmunds, 1974; Martin et al ., 2022). Factors such as prey body size (Bae et al ., 2019; Caro, Raees & Stankowich, 2020; Emberts et al ., 2020) and the distance between prey and predator (Loeffler‐Henry, Kang & Sherratt, 2021) can influence the efficacy of flash behaviour. For instance, contrasting colour patterns that may be effective in flash behaviour were associated with larger body size in some insect groups (Kang, Zahiri & Sherratt, 2017; Loeffler‐Henry, Kang & Sherratt, 2019; Caro et al ., 2020).…”

“…For instance, contrasting colour patterns that may be effective in flash behaviour were associated with larger body size in some insect groups (Kang, Zahiri & Sherratt, 2017; Loeffler‐Henry, Kang & Sherratt, 2019; Caro et al ., 2020). A greater escape distance between the prey and its predator improves survivorship as the predator is less likely to observe the prey's cryptic appearance at rest (Loeffler‐Henry et al ., 2021).…”

A synthesis of deimatic behaviour

“…However, a ‘proof of concept’ experiment demonstrated that the confusion effect of flash behaviour alone is sufficient to prevent attacks (Loeffler‐Henry et al ., 2018). Moreover, flash displays may be more effective in reducing predation when the signaller flees from a distance, so that the signaller's cryptic resting state is not observed (Loeffler‐Henry, Kang & Sherratt, 2021). Since hidden signals are less likely to frighten the observer when exposed from a distance, then deimatic and flash displays are functionally distinct and may often be incompatible.…”