Vigilance in a solitary marsupial, the common wombat ( Vombatus ursinus )
Résumé
Westudied vigilance activity in a wild population of the common wombat (Vombatus ursinus), a large, solitary,
burrow-using, marsupial prey species in which individuals tolerate the presence of conspecifics within their home range.
For the first time, we report postures and rates of vigilance in common wombats; our results show a limited repertoire of
vigilant postures and low overall rates of vigilance. Because few studies of birds and mammals that have reported the effect
of distance to conspecifics on the vigilance of focal animals have considered solitary prey species, we tested this effect in
wombats. Our results show that a model including distance to cover and distance to the nearest conspecific, but not time
of day, best explained the variation in the proportion of time that focal individuals spent in vigilance. Individual vigilance
decreased when distance to cover increased. Vigilance of wombats increased when there was a conspecific within a radius of
70m of the focal individual. In addition, we tested whether pairs of nearby wombats scanned independently of one another,
coordinated their activity in non-overlapping bouts of vigilance or synchronised their bouts of vigilance. Wombats in close
proximity exhibited independent bouts of individual vigilant and foraging activity. Thus, in this solitary species, our results
support the assumption that individuals scan independently of each other.