HUMAN HARVESTING IS THE MOST PERVASIVE THREAT TO LARGER VERTEBRATE AND INVERTEBRATE ANIMALS

Body size is strongly associated with extinction risk in living vertebrates, largely due to direct hunting and fishing pressures. However, it remains uncertain whether similar patterns and pressures affect the non-vertebrate animal majority, which hinders our understanding and ability to support conservation efforts. In this study, we integrate a comprehensive database of body size for over 40,000 animal species, representing three phyla and ten Linnaean classes, with Red List data on overall threat status and the impacts of 12 threat types. This approach enables us to assess the relationship between extinction threats and animal body size, encompassing both vertebrates and invertebrates. We find that the association between larger-sized species and elevated threat is pervasive in birds, mammals, reptiles, and cartilaginous fishes, with all threat types preferentially affecting larger species. By contrast, the association between size and overall threat varies across non-vertebrate classes and their constituent orders and families. Notably, among the various threat types, harvesting stands out as highly prevalent and consistently affecting larger species in both vertebrate and non-vertebrate classes. Mitigation of harvesting impacts would be the single most important step to reduce the geologically unprecedented extinction threat to larger-bodied animals. These findings extend previous research indicating that human preference for harvesting larger species across phyla and classes may explain the unusual size bias of the “Sixth” extinction, which is without precedent in the geologic record.