Self-defence may not be enough: moonlight avoidance in a large, spiny rodent

Predation avoidance is one of the main factors determining nocturnal activity of mammals, which has been shaped by evolution in relation to local environmental variables. The nocturnal activity of 16 female and 11 male radio-tagged adult crested porcupines Hystrix cristata was studied in four study sites of Southern Tuscany (Central Italy), with different environmental features. The activity patterns of porcupines, monitored for 16-23h per week per individual, were correlated to lunar phases, in open/closed habitat types, throughout the year. The median duration of nocturnal activity was 7h and 38min, with no significant seasonal variation. Moonlight avoidance was shown in all our study sites, throughout the year, especially in open habitats. Full moon, irrespective of its visibility, always inhibited activity of this large rodent. Old World porcupines originated 5 million years ago in the forests of Asia and Africa, where a number of large carnivores must have preyed - and still prey - on them. Most likely, moonlight avoidance evolved as an antipredatory behaviour. In areas with no or little predation risk for example our study sites, moonlight avoidance could have been kept in the repertoire of porcupines because of its non-maladaptive nature.