Latrine behaviour and faecal corticosterone metabolites as indicators of habitat-related responses of wild rabbits to predation risk

Abstract

Predation risk avoidance can be of crucial relevance for prey species like the European rabbit (Oryctolagus cuniculus). We evaluated whether the potential predation risk induced by the presentation of red fox (Vulpes vulpes) faeces influenced behavioural and physiological stress responses of rabbits, and whether these responses were modulated by the habitat structure. Fieldwork was carried out in holm oak forests and grasslands where 64 latrines were twice-daily monitored during 5 days (control phase), followed by an experimental phase (5 days) where half of the latrines were treated with red fox faeces and the other half remained as controls. Latrine activity and use were recorded as the percentage of active latrines, the number of days of activity and pellet counts. Further, fresh faecal pellets were daily collected from each latrine and we later quantified fecal corticosterone metabolites (FCM) in the laboratory as an indicator of the animalś physiological stress response. Behavioral and physiological stress responses varied depending on the time of day, during the night latrine activity and use were greater while rabbits showed lower FCM levels. The percentage of active latrines and the number of days of activity significantly decreased during the experimental phase in those latrines treated with red fox faeces. Likewise, pellet counts were noticeably reduced due to red fox faeces but only in holm oak forests. Regarding the physiological stress response, increased FCM levels were found in latrines with fox faeces but this reaction was only found in holm oak forests. These results suggest that, when facing predator cues, the antipredatory strategy of rabbits mainly relies on avoiding risky areas and reducing activity, whereas the physiological stress response seems to be more complex resulting from the synergy of direct (predator faeces) and indirect (habitat traits) cues associated to predation risk.