Frequent bird movements across a highly fragmented landscape: The role of species traits and forest matrix

Previous studies that tracked the movements of single bird species within human-modified landscapes have shown that the ability of forest birds to move across matrix habitat differs among species. Functional guild specificity as well as landscape characteristics have been shown to influence bird movements, entailing different movement behaviour of birds within a community. Studies investigating how both these factors influence the movements of entire bird assemblages across fragmented landscapes are essential but have rarely been conducted. In this study, we determined how species' traits and different forest matrices influence bird movements among nine forest patches in a highly fragmented South African landscape. We combined 90h of bird observations with capture-mark-recaptures (104754 mist-net hours) to distinguish between movements among patches (all birds that conduct long-distance movements across the landscape) and movements within patches (all resident birds that conduct only short-distance movements within a fragment). Overall, we detected a high bird movement activity across the fragmented landscape. Dietary specialization, habitat affinity and body mass strongly shaped the relative distribution of bird species across the nine fragments with frugivorous birds, forest specialists and large-bodied species showing the highest movement abilities. In contrast, resident insectivores and forest generalists tended to move only within particular forest fragments. Our results suggest that remnant forest fragments may represent valuable stepping stones as well as permanent habitat for local bird assemblages. We emphasize that beside the conservation of natural forests, the maintenance of nearby, structurally rich forest fragments is pivotal in maintaining regional forest bird assemblages in human-modified landscapes. © 2012 The Authors. Animal Conservation © 2012 The Zoological Society of London.