Camera traps reveal arboreal behaviour of the wood mouse Apodemus sylvaticus in hedgerows

Wood mice, Apodemus sylvaticus Linnaeus, 1758 are abundant in farmland hedgerows that are of conservation concern in northwest Europe. We used modified, baited camera traps to investigate arboreality in A. sylvaticus at different heights in hedgerows. Camera traps were set at seven sites at 0 m, 1 m and 2 m high in hedgerows. Mice were first live-trapped and marked using fur clipping, making them identifiable in subsequent camera trap videos. Most 30 s videos involved only solitary mice. The presence of marked animals at ground level and above suggests that A. sylvaticus exploit hedges from their base upwards. There was less activity of individual mice higher in the hedge which may be related to the risk of predation. Mice quickly accessed ground level and elevated camera traps after sunset, suggesting familiarity with vertical and horizontal hedgerow dimensions. Most solitary A. sylvaticus, particularly marked individuals, engaged in feeding. The mouse present first was more likely to feed than later arrivals; social behaviour was relatively consistent regardless of height. The vertical dimension in hedgerows is important to A. sylvaticus, an ecologically significant component of European hedgerow ecosystems. Sspatial behaviour of rodents in hedgerows deserves further investigation involving vertical and horizontal dimensions.