Field experiments on the effectiveness of ‘eyespots’ as predator deterrents

@article{Stevens2007FieldEO,
  title={Field experiments on the effectiveness of ‘eyespots’ as predator deterrents},
  author={Martin Stevens and Elinor Hopkins and W. Craig Hinde and Amabel Adcock and Yvonne Connolly and Tom Troscianko and Innes C. Cuthill},
  journal={Animal Behaviour},
  year={2007},
  volume={74},
  pages={1215-1227}
}
Do animal eyespots really mimic eyes
TLDR
Although eye mimicry is plausible, there remains a lack of evidence to support it and most observations are at least equally consistent with alternative mechanisms, which means the debate can be resolved.
Conspicuousness, not eye mimicry, makes "eyespots" effective antipredator signals
TLDR
Three experiments find that the features which make effective antipredator wing markings are large size and higher numbers of spots, which support other recent work indicating that conspicuousness, and not eye mimicry, is important in promoting avoidance behavior in predators and that eyespots on real animals need not necessarily, as most accounts claim, mimic the eyes of other animals.
The anti-predator function of ‘eyespots’ on camouflaged and conspicuous prey
TLDR
It is found that the protective value of conspicuous wing spots, placed on artificial moth-like targets presented to wild birds in the field, is strongly affected by the attributes of the prey ‘animal’ on which they are found, and that protective signals can switch from being beneficial to costly under different contexts.
Resemblance to the Enemy’s Eyes Underlies the Intimidating Effect of Eyespots
TLDR
This study indicates that eye mimicry is an important factor evoking hesitation in predators, and presents direct evidence that this is because predators associate eyelike displays with the threat posed by their own enemies.
Number of eyespots and their intimidating effect on naive predators in the peacock butterfly
TLDR
It is unlikely that conspicuousness as such has selected for eyespots in the peacock butterfly, and it is suggested that it is simply the conspicuousness of eyespot patterns that is intimidating, possibly due to a sensory bias.
Eyespots interact with body colour to protect caterpillar-like prey from avian predators
Deflective effect and the effect of prey detectability on anti-predator function of eyespots
TLDR
It is concluded that deflective function may select for eyespots, and background may influence the deterring function of eyespots.
Predator mimicry, not conspicuousness, explains the efficacy of butterfly eyespots
TLDR
The eye-mimicry hypothesis explains the results better than the conspicuousness hypothesis and is thus likely to be an important mechanism behind the evolution of butterfly eyespots.
Artificial eyespots on cattle reduce predation by large carnivores
TLDR
It is shown that eyespots painted on cattle rumps were associated with reduced attacks by ambush carnivores (lions and leopards) and this is the first time eyespots have been shown to deter large mammalian predators.
Eye-spots in Lepidoptera attract attention in humans
TLDR
It is suggested that eye-spots may be effective at deterring predators because they are highly conspicuous signals that draw attention.
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References

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TLDR
The role of eyespots as antipredator mechanisms has been discussed since the 19th Century and the necessity to consider the potential influence of sexual selection on lepidopteran wing patterns, and the genetics and development of eyespot formation is highlighted.
The Function of Eyespot Patterns in the Lepidoptera
TLDR
It has been shown that many small passerines possess inborn responses to their predators, and it is probable that these are "parasitised" by the eyespot patterns of insects.
Prey survival by predator intimidation: an experimental study of peacock butterfly defence against blue tits
TLDR
The results showed that eyespots alone, or in combination with sound, constituted an effective defence; only 1 out of 34 butterflies with intact eyespots was killed, whereas 13 out of 20 butterflies without eyespots were killed, indicating that they are not distasteful.
Simulating a colour mutation : conspicuous red wings in the European Blackbird reduce the risk of attacks by Sparrowhawks
TLDR
It is here shown that Sparrowhawks, A. nisus, the most important predators of Blackbirds, also avoid mounts with red wings, and in tests with human observers, it was found that red-winged mounts were more conspicuous than normal mounts.
Disruptive coloration, crypsis and edge detection in early visual processing
TLDR
Disruptive coloration is effective by exploiting edge detection algorithms that are used to model early visual processing, and ‘false’ edges are detected within the body rather than at its periphery, so inhibiting successful detection of the animal's body outline.
Predator perception and the interrelation between different forms of protective coloration
  • M. Stevens
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    Proceedings of the Royal Society B: Biological Sciences
  • 2007
TLDR
This paper outlines how different forms of protective markings can be understood from predator perception and illustrates how this is fundamental in determining the mechanisms underlying, and the interrelation between, different strategies.
Does a Novel Bright Colour Patch Increase or Decrease Predation? Red Wings Reduce Predation Risk in European Blackbirds
TLDR
In the blackbird Turdus merula, whether a novel colourful plumage, resembling that of some American and African birds, increases or decreases the risk of predation is tested, which suggests that apostatic selection by predators may favour such mutants over longer time periods.
The Effect of Experience and Novelty on Avian Feeding Behavior with Reference to the Evolution of Warning Coloration in Butterflies. II. Reactions of Naive Birds to Novel Insects
TLDR
In this experiment, hand-raised birds avoided novel insects in a manner which showed that the rejection was not learned or innate, and suggest that there need not be an association with noxiousness in order for conspicuous coloration to be a selective advantage.
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