Night-time symphony: lunar effects on the activity patterns of the wolf and its prey in a Mediterranean protected area

Environmental drivers can influence animal behaviour, affecting movement patterns and spatial dynamics with a cascading effect. Furthermore, most species adapt their behaviour to ecological factors, such as predation risk. In human-dominated landscapes, most medium-to-large terrestrial mammals are crepuscular or nocturnal, limiting their opportunities for other temporal changes. However, the role of nocturnal illumination and the lunar cycle in these spatiotemporal patterns remains understudied. We used camera trapping data, kernel density estimation, and generalized additive models to analyse the effects of the lunar cycle and moonlight on activity patterns of wolves Canis lupus and their ungulate prey in a Mediterranean area, accounting for cloudiness and habitat. Our results give no support to spatial avoidance by prey, and wolves were spatially synchronized with them. Additionally, we found no evidence of changes in animal activity modulated by moon brightness. Instead, we identified more refined mechanisms driving the relationships between wolves and their prey. Specifically, wolves seemed to exploit darker nights in areas more frequently used by their main prey (i.e. wild boar Sus scrofa and fallow deer Dama dama). Wild boar were more active during the brightest nights in the sites most used by the predator, whereas fallow deer were more active in the sites used in an intermediate way by the wolf and during nights with a middle nocturnal light intensity. Roe deer Capreolus capreolus were slightly more active during darker nights and in more concealed sites. These outcomes suggest that animal activity patterns reflect a trade-off between species-specific physiological features (e.g. poor nocturnal visual acuity in wild boars), the need for foraging, prey availability, vigilance, predation risk, human disturbances, and ambient light levels. Our results contribute to shed light on the underexplored effects of lunar illumination on predator and prey activities and relationships, particularly in ecosystems experiencing the return of apex predators.