Under the Moon: Influence of Moon Brightness on Temporal Interspecific Relationships in a Mediterranean Carnivore Guild

Abstract

In terrestrial ecosystems, interactions between mesocarnivores and apex predators influence carnivore guilds, potentially affecting lower trophic levels. Spatiotemporal partitioning is a major factor shaping interspecific coexistence among carnivores. Since most carnivores are active at night, nocturnal illumination is expected to play a potentially critical role in mediating interspecific dynamics, but information is still scarce especially for areas recently recolonized by apex predators. This study investigated how the lunar brightness affected the activity of mesocarnivores, that is, the red fox Vulpes vulpes, the European badger Meles meles, and martens Martes spp., in a Mediterranean area recently recolonized by the wolf Canis lupus. Using year-long camera trapping data, we analyzed activity patterns as a function of brightness index (moonlight × cloud cover) and wolf detection rates. Responses to moonlight differed among species: while there were no detectable changes in the diel activity patterns of red fox across the different moonlight conditions, mustelid species showed a shift in the temporal peaks of activity with altered bimodal patterns between higher and lower moonlight. Fox nocturnal activity decreased significantly on brighter nights, likely reflecting synchronization with prey. In contrast, the activity of badgers and martens showed no significant changes in response to nocturnal brightness. There was support for a negative effect of wolf detection rates on those of badgers and, to a lesser extent, martens. However, we did not find evidence for an interactive effect of night brightness and wolf detection rate, suggesting that interspecific interactions were not modulated by nocturnal light. These findings highlight that lunar illumination has species-specific effects on nocturnal behaviors and emphasize the importance of habitat and interspecific relationships in shaping activity patterns.