Two decades of changes in the global network of illegal wildlife trade

Understanding how illegal wildlife trade (IWT) has changed over time is fundamental for biodiversity conservation; however, knowledge of the network remains limited. We used TRAFFIC's IWT dataset, legal trade data from the CITES legal wildlife trade database as a benchmark, and network analysis to identify changes in IWT from 2000 to 2022. The center of IWT shifted from Europe to Asia around the 2010s, especially through the direct flow of some species, such as rhinoceroses and pangolins, from Africa to Asia and within Asia. Despite the prominence of Africa and Asia, the network remained global and involved players on all continents, as demonstrated by a low tendency of high-degree nodes to connect to each other and a large core of about 50% of the nodes. The IWT network expanded significantly from 49 countries in 2000 to 110 countries in 2018. There was a similarly dramatic increase in the number of trade connections, from 52 edges in 2000 to 266 in 2018, highlighting the growing complexity of the trade. During the COVID-19 pandemic, the IWT network exhibited resiliency; there was only a gradual decline in participating countries from 90 in 2020 to 72 in 2021. Also, during the pandemic, network clustering and geodesic distance were maintained, underscoring IWT's adaptability despite global disruptions. These network properties explain the persistent nature of IWT and suggest constant monitoring is necessary to keep up with changes in the network.