Birds and alien species dispersal: on the need to focus management efforts on primary introduction pathways – comment on Reynolds et al. and Green

Two articles published in Diversity and Distributions (Green, 2015; Reynolds et al., 2015) demonstrate the role of waterbirds in dispersing alien species and claim that this phenomenon has been largely neglected. Setting out priorities for the future, they focus on the need to improve our understanding of the problem if it is to be successfully managed. We argue that birds are vectors of the secondary spread of alien species already introduced by human agency, rather than the pathway of their primary introduction. The challenge presented by unaided dispersal pathways, such as birds, will not be significantly reduced by future advances in our understanding of their mechanisms. The three-stage hierarchical approach, recommended by the Convention on Biological Diversity, remains the best management option for biological invasions, irrespective of the level of knowledge about their pathways.