New research on global biodiversity loss offers a clearer picture of how animal life is faring. Across major groups, a substantial portion of species are declining, while others remain stable or show modest gains. Researchers emphasize that much of the deterioration stems from habitat degradation driven by human activities, underscoring a troubling trend that many scientists refer to as the early stages of a sixth mass extinction.
Historically, the IUCN Red List has served as the primary barometer for assessing extinction risk. It classifies species into protection categories that signal how close they are to endangerment. Based on this system, roughly 28 percent of Earth’s species are currently considered threatened with extinction, a statistic that highlights the urgency of conservation actions around the world.
To gain a more detailed view, researchers analyzed population density shifts across more than 71,000 species spanning five vertebrate groups — mammals, birds, reptiles, amphibians, and fishes — and a wide array of insects. The study reports that about 48 percent of species are experiencing population declines, about 49 percent appear stable, and roughly 3 percent show increasing numbers. This comprehensive snapshot offers a more precise understanding of the pace and scale of biodiversity changes than previous methods.
In reflecting on the findings, study author Daniel Pincheira-Donoso notes that the global approach used provides a broader, clearer view of biodiversity loss than past techniques. Co-author Catherine Finn adds that nearly half of the animal species for which data exist are currently in decline, and that some species not traditionally viewed as endangered are quietly slipping toward risk. This pattern emphasizes that risk can exist beyond obvious red flags and underscores the need for vigilant monitoring across all taxonomic groups.
Additional analysis reveals that even species categorized as not endangered by the Red List are sometimes in decline. When looking at the data more closely, researchers found that about one in three species labeled as not at risk were nonetheless decreasing in numbers. If these trends persist, a further significant number of species could move toward threatened status in the near future, challenging assumptions about which animals are truly safe from decline.
Most endangered amphibians
Among the amphibians, the study shows a troubling pattern: population declines are most pronounced in tropical regions, while temperate zones show more stability and fewer increases. Not all taxonomic groups are affected equally; amphibians are notably more vulnerable, with about 63 percent declining compared with around 28 percent for reptiles. These disparities point to regional and physiological differences that shape risk trajectories for different life forms.
Researchers emphasize that the balance between species loss and potential gains matters. When declines outpace increases, the overall diversity of ecosystems erodes, leading to tangible losses in ecological services. The trajectories observed in these data describe a real reduction in biodiversity rather than mere reshuffling of species, and they signal mounting concern for the functioning of ecosystems that humans rely on for food, climate regulation, and health.
Taken together, the findings are often described as another indicator that global biodiversity is moving toward a critical threshold. The heterogeneity, resilience, and overall functioning of ecosystems, along with the benefits that biodiversity provides to human well-being, face escalating threats. The research underscores the need for robust conservation strategies and sustained international collaboration to curb habitat loss and support population recovery.
Note: this synthesis draws on the core results reported by the study and supported by additional analyses of species trends. For researchers and policymakers, the work offers a framework to monitor change at a global scale and to target conservation efforts where they are most needed.