Friday, 26 September 2025
Which type of coloration provides prey with the best protection from predators? An international team of scientists, including zoologists from the Faculty of Science, Charles University, tested 15,000 artificial moths placed across six continents to determine whether conspicuous warning coloration or inconspicuous camouflage is more effective. The results revealed that there is no single winning strategy – the outcome depends on environmental conditions, community composition, and predator behaviour. The study was published in the current issue of Science.
Some animals use bright colours and patterns to deter predators, while others rely on cryptic coloration that allows them to escape detection. The evolution of different types of antipredator coloration has been a key topic in evolutionary biology since the time of Charles Darwin, yet many fundamental questions remain unanswered. One of these questions is which ecological factors determine why some species evolve cryptic and others warning coloration.
A new perspective on this issue is provided by a study published in Science, and the answer turned out to be more complex than expected. The study is based on the results of a large-scale international project led by William Allen (Swansea University) and Iliana Medina (University of Melbourne), with participation from Alice Exnerová, Klára Daňková, Anita Szabó, Kateřina Hotová-Svádová, and Marie Truhlářová (Department of Zoology, Faculty of Science, Charles University), Tomáš Albrecht (Faculty of Science, Charles University and Institute of Vertebrate Biology, Czech Academy of Sciences), and Jan Raška (Faculty of Science, Charles University and Czech University of Life Sciences Prague).
The researchers conducted a global field experiment in which they placed a total of 15,000 artificial “moths” at 21 forest sites across six continents and monitored their predation by local bird species. From a biogeographical perspective, the inclusion of two Afrotropical sites, particularly Mt Cameroon, was notable. There, the experiment was carried out by a team of scientists and students from the Department of Zoology, Faculty of Science, Charles University, continuing a long-term research tradition in Cameroon led by teams from Charles University and the Institute of Vertebrate Biology, Czech Academy of Sciences.
The artificial prey had three colour types: a typical warning pattern of orange and black, a cryptic brown coloration, and an atypical bright blue-and-black pattern. By comparing predation rates across different conditions, the scientists found that there is no single globally optimal strategy. The success of each type of defensive coloration depended on predator community composition, the prevailing coloration of local prey species, as well as vegetation structure and light conditions.
The composition of the predator community had the strongest influence on which type of coloration was more successful. When predators compete intensely for food, they are more likely to attack prey that might otherwise be considered dangerous. In areas with high predation pressure, camouflage proved more effective than warning signals. However, cryptic coloration was not always successful – its effectiveness also depended on vegetation structure and light intensity. In bright environments, camouflaged prey was more visible and thus attacked more often than prey with warning coloration.
The composition of the local prey community also played a key role. A higher proportion of cryptically coloured butterflies and moths reduced the effectiveness of camouflage because predators had more opportunities to learn to detect such prey. Conversely, when warningly coloured – and thus often toxic or dangerous – species predominated, predators tended to avoid prey with such coloration due to prior negative experience.
The results of the study demonstrate how various ecological factors together determine which antipredator strategy is more advantageous and help us better understand the evolution and global distribution of the main types of animal coloration. In the future, it would be interesting to explore whether similar factors influence antipredator strategies in other environments, such as aquatic ecosystems. The study also highlights the value of broad international collaboration, without which many fundamental questions in ecology and evolutionary biology would remain unanswered.
Original study:
Iliana Medina et al., Global selection on insect antipredator coloration. Science 389, 1336–1341 (2025). DOI: 10.1126/science.adr7368