Influences of hedgerow intersections and gaps on the movement of carabid beetles

In the fragmented landscape of arable farmland, hedgerows and other non-cro p habitats provide refuges of food and shelter for invertebrates, and corri dors through which they can move to other habitats. Their role as corridors is likely to depend on their connectivity, both to each other and to other patches of suitable habitat. The effects of connectivity on the carabid be etle Nebria brevicollis (Fabricius) were analysed by observing movement bet ween hedgerow intersections (nodes) and the linear section of the hedgerow, and across gaps in the hedgerow. Capture-mark-recapture of N. brevicollis revealed a uniformly higher activity at hedgerow nodes than at mid-section strips of comparable area. This is consistent with previous studies of hedg erow fauna including butterflies, plants and birds. Gaps in the hedgerows t ypically measured 7-9 m and functioned as a passage between fields for farm machinery. These were readily crossed by N. brevicollis as was the hedge b ottom. Some movement along the hedgerow was found indicating their use as a corridor.