Quantifying Global Colonization Pressures of Alien Vertebrates in Trade

Abstract

Abstract The increased trade in live wildlife for pets and other uses potentially elevates colonization pressure, and hence the risk of invasions. Yet, we have limited knowledge on number of species traded outside their native ranges as aliens. We create the most comprehensive global live terrestrial vertebrate trade database, and use it to investigate the richness of alien species in trade, and correlates of establishment richness, for aliens across countries worldwide. We identify 10,378 terrestrial vertebrate species in the live wildlife trade globally. Approximately 90.1% of these species are aliens, and 9.1% of the aliens establish populations. Large numbers of alien species have been imported to countries with high incomes and large areas. Such countries are also hotspots for establishment, along with some island nations. Colonization pressure and insularity consistently promote establishment richness across countries. Socio-economic and climatic factors are also associated with establishment richness for different taxa. This study identifies daunting challenges to global biosecurity from future invasion risks posed by wildlife trade.