Fire melanism and predator-mediated selection in cicadas from fire prone forests

Background Adult Mediterranean cicadas exhibit species-specific habitat preferences in fire-affected environments, seemingly influenced by body color. The grey Cicada orni tends to avoid burnt trees, whereas black or darker cicadas of the genus Tibicina are often found on charred tree trunks. This study explores the role of predation in shaping these behaviors, within the context of the fire melanism hypothesis, which postulates the darkening of certain animals in frequently burned ecosystems. We used wax cicadas mimicking of Cicada orni and Tibicina spp., validated by multispectral imaging, to quantify predation rates on contrasting backgrounds, grey (unburnt bark) and black (burnt bark). A total of 480 cicada models were installed on 240 trees in burnt and adjacent unburnt Mediterranean forests in three fire-affected areas, and 11–16 camera traps were deployed to monitor predator interactions. Results The birds Garrulus glandarius , Dendrocopos major, and Parus major attempted to prey on the models. Predation attempts were higher for black models on unburnt bark and grey models on burnt bark, suggesting an important role for background contrast in predator detection. Conclusions Our findings support the fire melanism hypothesis, suggesting that black coloration enhances survival in post-fire environments. This study underscores predation as a key factor driving post-fire ecological and behavioral differentiation.