Coming back home: recolonisation of abandoned dens by crested porcupines Hystrix cristata and European badgers Meles meles after wood-cutting and riparian vegetation mowing events
Semifossorial species excavate dens and are considered as landscape engineers, often responsible for soil oxygenation, shuffling, landslides and floods. The crested porcupine and the European badger are semifossorial mammals sharing dens in central Italy. Both species localise their setts mainly in densely vegetated areas, providing them with cover and protection from local predators and poachers. This is particularly evident for the porcupine, widely poached in central and southern Italy, whereas badgers may locally exploit burrows also in open and periurban areas. Wood-cutting and mowing of riparian vegetation surrounding den setts force both porcupines and badgers to leave their burrows. We evaluated the probability of den re-occupancy in the years following the vegetation removal, through intensive camera-trapping at 14 den setts monitored for 9 years. We performed GLMMs to test the annual probability of sett occupancy by the two species after vegetation disturbance events. The probability of re-occupying the burrow by porcupines increased with increasing time from the disturbance cessation. A similar pattern was also observed for the badger, which probability of den occupancy was also negatively correlated with the porcupine presence at the same den, confirming the aggressive behavior of this rodent. We also tested whether, since the first year after vegetation removal, the proportion of years of occupation by porcupines on the total of years has been affected by the disturbance repetition. This effect was found to be significant only for the badger. The crested porcupine, protected by international and national laws, is more sensitive than the badger, protected according to the Italian national law, to vegetation removal. A single disturbance event is sufficient to force it to abandon the den sett, followed by a slow recolonisation with growing vegetation. Conversely, the badger is sensitive to continuous vegetation removal whereas it can colonise porcupine dens abandoned after single disturbances
