A global experiment looking at how birds respond to 15,000 paper "moths" reveals that no color-changing strategy to deter predators is universally effective; both camouflage and warning coloration succeed under different ecological conditions, the study shows. Predation is a powerful force shaping evolution, driving the development of two major antipredator color strategies: camouflage, which helps prey to blend into their surroundings to avoid detection, and aposematism, in which prey advertise genuine defenses or, in the case of mimics, deceptive protection, using bright and conspicuous warning colors. Both strategies can be effective under different ecological conditions, yet the environmental factors that favor the development of one adaptation over the other are not well understood, nor have they been evaluated together or across large scales.
To address these questions, Iliana Medina and colleagues conducted a large-scale, global field experiment to test how birds respond to different antipredator color strategies. Medina et al. placed 15,018 paper moth models – some camouflaged brown, some with typical orange-black warning colors, and some with unusual turquoise-black warning patterns – across 21 forests on 6 continents. Each model included a mealworm to attract predators, and consumption was monitored to assess successful predation. According to the findings, no strategy was universally superior; instead, the protective value of each type depended on ecological context. The authors found that camouflage was highly context-dependent, offering early protection under low light or high predator competition. However, camouflage lost effectiveness as predators adapted or cryptic prey became common. In contrast, warning coloration was generally more reliable, though its success was shaped by predator pressure, the frequency and similarity of warning-colored prey in the community, and other ecological factors, especially in lower-latitude environments. Medina et al. show that predator competition is the most influential factor for both strategies and suggest that camouflage may be a less stable defense strategy, one more susceptible to environmental and human-driven changes. This instability could explain why camouflage is gained and lost more frequently than warning coloration over evolutionary time.
