The gravity of wildlife trade

Unsustainable trade in wildlife products both legally and illegally is a leading cause of population declines and increased extinction risk in commercially valuable species. However due to the clandestine nature of illegal trade and paucity of overarching studies of legal trade our understanding on international trade networks is patchy. We develop a gravity-underreporting modelling framework to analyse and compare: (i) data on the legal trade in mammalian, avian and reptilian products from recorded by The Convention on the International Trade in Endangered Species of Wild Fauna and Flora (CITES) and (ii) to data on the seizures of illegal products entering the USA between 2004 and 2013. We find substantial differences in the factors driving legal trade for the 3 taxonomic groups considered, indicating different drivers for different product markets. Illegal imports for all groups were associated with increasing exporter GDP. We found higher probabilities of underreporting for avian and reptile products, and in general central Africa, central Asia, Eastern Europe and Pacific Island states showed higher underreporting than other regions, indicating the existence of complex trade networks and the potential for the laundering of illegal products through legal markets. Our results show the important regional and economic trends driving wildlife trade. Our new modelling framework can also help illuminate previously unseen aspects of illegal and legal wildlife trade, which can help with the implementation of interventions to curb the impact of trade on wild populations.