Nature’s disguise: empirical demonstration of the dead-leaf masquerade in Kallima butterflies

Animals deploy diverse colour-based defences against predators, including crypsis, mimicry, aposematism and masquerade. While the first three have been extensively studied, masquerade—where organisms resemble inedible or inanimate objects like leaves, twigs, stones and bird-droppings—remains less explored, particularly in the context of adult butterflies. The wings of Indian oakleaf butterfly (Kallima inachus), resemble dead leaves, and serve as a classic example of natural selection. Despite the longstanding assumption that these butterflies gain protection by being misidentified as dead leaves, direct evidence is lacking. To address this gap, we conducted experiments using domestic chicks as predators. By manipulating chicks’ prior experience with dead leaves (model objects) while maintaining constant exposure to butterflies, we tested the hypothesis that dead-leaf masquerade provides a protective advantage via preventing recognition. The results revealed a significant delay in the attack behaviour of chicks with prior dead-leaf experience to butterflies compared to naïve or visually-altered-leaf exposed chicks. Chicks with prior dead-leaf experience took a comparable amount of time to attack butterflies as they attacked dead leaves. These findings present the first empirical demonstration of dead-leaf masquerade in Kallima butterflies, shedding light on the evolutionary significance of masquerade. The study highlights the effectiveness of masquerade in inducing the misclassification of butterflies as inanimate objects, showcasing a perfect resemblance when viewed in isolation from their model objects. This contribution advances our understanding of the evolution of masquerade and underscores its role as a powerful antipredator strategy in nature.