Study
Conspicuousness, not eye mimicry, makes eyespots effective antipredator signals
Stevens, Martin; Hardman, Chloe J.; Stubbins, Claire L.
Behavioral Ecology, 2008
Presented artificial prey to wild birds carrying marks that varied independently in how eye-like they were and in how conspicuous they were — including circular eye-like marks, equally conspicuous bars and squares, and less conspicuous versions of each — and scored survival.
- Studied in
- Aves, Lepidoptera
- Sample size
- artificial prey targets exposed to wild bird predation
Survival was predicted by conspicuousness rather than by resemblance to eyes. Highly conspicuous non-circular marks protected prey as well as eye-like circles of equivalent conspicuousness.
What it means
The authors' reading, and ours. Where they differ, that difference is the point.
How the authors put it
Eyespots deter predators because they are highly conspicuous signals, not because they resemble the eyes of a larger animal.
How NatureHQ reads it
The experiment that separated two explanations which a century of observation had left tangled. It is the clearest case in this corpus of an intuitively appealing hypothesis being tested against its rival and losing — and the design is simple enough that the delay in running it is the surprising part.
- Artificial prey with abstract marks rather than real butterflies, so how far it explains any particular species is untested.
- Avian predators in one region; a mammal or reptile might respond differently.
- It does not exclude eye mimicry mattering in some specific cases, only that conspicuousness accounts for the general effect.
Circles, bars and squares
Do eyespots deter birds because they look like eyes, or because they are simply very hard to ignore?
What this study is used for on NatureHQ
One study can inform several subjects. Here is everywhere this one is cited.
Warning coloration
Bright colouring is not a reliable guide to whether an animal is dangerous. Conspicuous animals may be signalling to mates, mimicking something defended, or simply not conspicuous to the eyes that matter.
Eyespots
Butterfly eyespots do deter birds — but apparently not by looking like eyes. When conspicuousness and eye-likeness were varied separately, equally conspicuous bars and squares protected prey just as well as circles.
Published by: University press journalsPublished in a university press journal.
Checked against Crossref on 2026-09-28, and they agree on the title, the authors and the year.
NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-09-03.