Expanding through the Emerald Isle: exploration and spatial orientation of non-native bank voles in Ireland

Abstract

Whether introduced into a completely novel habitat or slowly expanding their current range, the degree to which animals can efficiently explore and navigate new environments can be key to survival, ultimately determining population establishment and colonisation success. We tested whether spatial orientation and exploratory behaviour are associated with non-native spread in free-living bank voles (Myodes glareolus, N = 43) from a population accidentally introduced to Ireland a century ago. We measured spatial orientation and navigation in a radial arm maze, and behaviours associated to exploratory tendencies and risk-taking in repeated open-field tests, at the expansion edge and in the source population. Bank voles at the expansion edge re-visited unrewarded arms of the maze more, waited longer before leaving it, took longer to start exploring both the radial arm maze and the open field, and were more risk-averse compared to conspecifics in the source population. Taken together, results suggest that for this small mammal under heavy predation pressure, a careful and thorough exploration strategy might be favoured when expanding into novel environments.