A framework to assess trajectories of societal and biological extinction

Threatened species that are societally extinct, which refers to the loss of a species' presence in human societies, are less likely to receive conservation attention, potentially resulting in their biological extinction going unnoticed. However, little is known about the process and forms of such extinction. Thus, we aimed to quantitatively demonstrate the concept of societal extinction. We hypothesized that societal extinction leads to reduced conservation efforts for the affected species, which may, in turn, be associated with their biological extinction. We developed a framework for the trajectories between societal and biological extinction that involves four corner states and nine pathways of societal presence that can be characterized using quantitative metrics. A case study was conducted using Google Trends data for species listed on the 2020 Japanese Red List, together with information on private-sector contributions to conservation. Notably, more than half of the species remained societally threatened, meaning they were close to societal extinction. In contrast, conservation efforts, such as tax donation schemes and nonmonetary corporate contributions, were primarily directed toward societally extant (particularly prevalent) species that were consistently searched over time. A small number of biologically extant species were nevertheless societally threatened, suggesting a potential divergence between the biological and societal status of species. Thus, species that are not only biologically but also societally threatened should be prioritized as targets for public conservation efforts, as they are less likely to receive sufficient support from the private sector. To inform future research efforts, we also summarized data on the societal presence of a selection of species from multiple perspectives beyond Google Trends.