LAUSR

Alien birds are widely distributed across the globe, but information on their environmental impacts is available for less than a quarter of the regions in which they are located. We test a series of hypotheses better to understand why impact data are available for some regions but not others. Information on factors hypothesised to influence spatial variation in the availability of impact data were collated for 60 regions with actual, recorded alien bird impacts, and 187 regions without. These data were analysed using mixed effects models. The characteristics of alien bird invasions most strongly influence the availability of impact data, which are more likely to be available for regions with higher alien bird species richness and longer alien bird residence times. There are many regions of the world that lack impact data but are characterised by high alien bird species richness and long alien bird residence times: it is likely that the impacts of alien birds are going unnoticed within them. To a lesser extent, impact data are also more likely to be available for regions characterised by higher economic development. Improving the capacity for research amongst less developed regions may therefore be a key strategy to improve our understanding of the impacts of alien birds. Impact data availability was not found to be associated with impact severity, and therefore we cannot conclude that regions lacking impact data do so because the impacts sustained within them are less severe.