Detecting mammals in heterogeneous landscapes: implications for biodiversity monitoring and management

With terrestrial mammals facing worldwide declines there is an increasing need to effectively monitor populations so that appropriate conservation actions can be taken. There are many techniques available to survey terrestrial mammals and in recent years there have been a number of studies comparing the effectiveness of different methods. Most of these studies have not considered complementarity (the degree to which techniques detect unique species) and effectiveness across ecological gradients. In this study we examined three widely used techniques, camera trapping, live trapping and hair detection, for their complementarity across a vegetation and disturbance gradient. Overall, camera trapping detected more species than any other single technique, but live trapping complemented the cameras by consistently detecting unique species. Additionally, technique effectiveness differed between vegetation types; cameras alone were most effective in dry forest systems while cameras combined with live traps were most effective in wetter forest systems. These results suggest that care needs to be taken when sampling across heterogeneous landscapes because relying on one technique alone could result in certain taxa being systematically overlooked, leading to potentially erroneous conclusions.