Human‐Induced Extinction Risk of the World's Crocodilians and Chelonians

Abstract

Aim Human activities have profoundly altered biodiversity and ecosystems worldwide, particularly impacting freshwater systems crucial for many reptile species, such as crocodilian and chelonian species, many of which rely heavily on freshwater habitats. Here, we assessed the influence of human‐altered variables (human footprint, aridity index, and livestock layers) and conservation lands on global crocodilian and chelonian species richness and the status of threatened species using IUCN Red List categories to assess extinction risk. Location Global. Time Period Present and Future. Taxa Studied Crocodylia and Chelonia (continental tortoises and turtles, not sea turtles). Methods We used spatial regression models with global data sets on species distributions, anthropogenic pressures, and conservation lands to examine the effects of human‐altered variables and conservation lands on global crocodilian and chelonian species richness. Results According to the IUCN Red List, 42% of the crocodilian and 51% of the chelonian species are globally threatened (CR, EN, VU). Anthropogenic factors, including aridity, human footprint and livestock density, were significantly negatively correlated with species richness. In contrast, the extent of freshwater habitats (FWH), indigenous peoples' lands (IPLs) and protected areas (PAs) were key predictors of species persistence worldwide. Main Conclusions Our projections for FWH and IPLs indicate a concerning decline, threatening the availability of safe havens for these taxa. This trend, coupled with escalating anthropogenic pressures, poses a dire threat to conservation lands and the species that depend on them. We strongly recommend the establishment of robust national and international policy frameworks to promote sustainable livelihoods and alleviate human‐induced pressures. These measures are vital for mitigating extinction risks and ensuring the long‐term conservation of crocodilian and chelonian species and the ecosystems they inhabit.

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