IUCN Red List underestimates national conservation needs of transboundary species

The IUCN Red List of Threatened Species is a criteria-based approach to evaluate extinction risk of species on a global scale. However, governments prioritise species conservation within national boundaries, and species categorized as non-threatened in the IUCN Red List may receive limited conservation efforts in countries where they are threatened with regional extinction. We compared threatened categories of 2598 vertebrate species distributed in China evaluated by the IUCN Red List (international) and by China's Red List (national). We found a higher proportion of threatened species in the National Red List than in the IUCN Red List, primarily due to the higher extinction risk of transboundary species, which have distribution ranges crossing national borders, in the National Red List. Specifically, the extinction risk evaluated under the National Red List was much higher for transboundary species (20%) than in the IUCN Red List (10%), while the difference was small for endemic species (43% in the National Red List and 37% in the IUCN Red List). In addition, transboundary species from understudied taxonomic groups such as reptiles and amphibians exhibited higher between-list differences relative to well-studied groups such as mammals and birds. Our results suggest that the IUCN Red List underestimates national conservation status of transboundary species, highlighting the critical importance of developing national red lists for understudied taxa in developing countries. Our study also underscores an urgent need for cross-border cooperation in species population monitoring, scientific research, and conservation practices to conserve threatened transboundary species.