Global change significantly threatens wildlife populations, necessitating the identification of key drivers of population trends to understand both declines and potential recovery pathways. While the impact of land-use change and climate change on wildlife is well-studied, the role of socioeconomic factors remains relatively unexplored. Existing research suggests a significant influence of socioeconomic factors, with wildlife populations often thriving in areas with strong governance and high living standards. This study addresses this knowledge gap by investigating the relative contributions of land-use change, climate change, governance (inclusive of socioeconomic factors), and species traits on population trends of large terrestrial carnivores. These charismatic and functionally important animals serve as an ideal study group due to their widespread distribution and the availability of extensive data on their populations. The study aims to quantify the influence of each factor on carnivore population change, emphasizing the crucial role of socioeconomic factors and projecting the potential impact of socioeconomic development on carnivore populations over the past 50 years. The anticipated outcome is evidence demonstrating a strong association between rapid socioeconomic development and carnivore declines, while also highlighting the potential for recovery once development slows. This analysis will provide insights into strategies and scenarios for improving biodiversity conservation.

A wealth of ecological research exists on the local-scale effects of environmental changes, such as land-use alteration and climate shifts, on species population trends. However, studies examining the role of socioeconomic factors in shaping these trends are comparatively scarce. Available research indicates that strong governance and high standards of living positively influence wildlife populations. To effectively discern the impact of environmental and socioeconomic factors, a multidimensional approach is crucial, encompassing the diversity and context-dependence of factors influencing population dynamics. This study builds upon previous research that highlights the positive correlations between wildlife abundance and both human development and governance, offering a more comprehensive analysis with a global scope and a focus on large carnivores.

The study compiled population trend data for 87 large carnivore species from four families (Canidae, Felidae, Hyaenidae, and Ursidae) from the CaPTrends and Living Planet databases. The data included both quantitative estimates of abundance change (converted to annual rates of change) and qualitative descriptions of change (increase, stable, decrease). A total of 1123 population trends were analyzed, representing 50 species across 75 countries. For each trend, sixteen covariates were extracted, describing land-use, climate, governance (including socioeconomic factors), and species traits. A hierarchical Bayesian linear model was used to analyze the data, integrating both quantitative and qualitative trend data using a censored response term to account for the uncertainty in the qualitative data. The model included 16 covariates and 7 interactions, allowing the impact of environmental change to be assessed in relation to species traits, governance, and interactions between different environmental changes. Variable selection was employed to avoid model overparameterization. To determine the relative contributions of habitat loss, climate change, and human development, three counterfactual scenarios were developed. These scenarios involved setting the values of these three variables to zero, while holding other covariates constant, enabling the estimation of changes in population trends had these factors not been present. To explore the non-linear effects of human development, simulations were conducted using three idealized socioeconomic pathways (slow, moderate, fast) that differed in their mean rate of change in human development, but all included a shared deceleration rate. These pathways were used to project carnivore abundances over time, keeping other covariates constant at their average global values. This allowed the researchers to isolate the effects of changing human development.

The analysis revealed several key findings: 1. **Socioeconomic Development's Dominance:** The study found that changes in human development, representing a holistic measure of socioeconomic factors, were the strongest predictor of carnivore population changes. This effect surpassed those of both habitat loss and climate change. Rapid human development growth was associated with carnivore population declines. Counterfactual analysis showed that nearly all carnivore populations would have higher abundances had there been no human development growth. 2. **Habitat Loss:** Primary habitat loss was negatively associated with carnivore populations, aligning with expectations. However, the interaction between habitat loss and other factors (ecological niche breadth, human density, and change in natural land) was not significant, suggesting that declines occur regardless of species specialization or habitat replacement type. 3. **Complex Climate Change Effects:** Climate change effects were complex. Increased frequency of extreme heat events had no consistent effect overall, but populations outside protected areas declined while those within protected areas showed growth, suggesting the mitigating effects of protected areas. The unexpected positive association between increased drought frequency and population trends may be due to short-term improvements in prey availability, although further investigation is needed. 4. **Non-Linearity:** The relationship between human development change and carnivore population trends was non-linear. While rapid human development growth led to declines, population growth could occur once growth rates fell below approximately 1.2%. This resembles a Kuznets curve pattern where environmental degradation increases during industrialization, plateaus, then decreases as economies develop. Simulations demonstrated that smaller differences in development change can lead to vastly different outcomes for carnivore populations. 5. **Limited Habitat and Climate Impacts:** Despite the large effects found for habitat loss and climate change in certain populations, the overall contribution of these factors in the counterfactual scenarios was not substantial. This is likely due to a sampling bias where the study lacked data from populations experiencing extreme habitat loss and climate change, leading to underestimation of their effects.

This study provides compelling evidence that socioeconomic factors are paramount drivers of large carnivore population change, exceeding the influence of habitat loss and climate change. The non-linear relationship between human development and carnivore abundance emphasizes the importance of considering the rate of development when assessing biodiversity impacts. While habitat loss and climate change remain threats, the strong influence of human development suggests that addressing socioeconomic factors is crucial for both preventing declines and fostering the recovery of carnivore populations. The findings highlight the need for integrated conservation strategies that consider not just environmental factors, but also the socioeconomic context within which conservation efforts occur. This includes addressing factors like poaching pressure, human-wildlife conflict, and changing societal attitudes towards wildlife.

This research demonstrates the critical role of socioeconomic factors in shaping large carnivore population trends, surpassing the impacts of habitat loss and climate change. The non-linear relationship between development change and carnivore abundance underscores the importance of slower development rates for biodiversity conservation. Future research should explore the mechanisms by which socioeconomic factors influence carnivore populations, develop strategies to mitigate negative impacts, and assess the generalizability of these findings to other taxa. Integrating socioeconomic factors into biodiversity conservation strategies is essential for achieving conservation goals and the UN Sustainable Development Goals.

The study acknowledges limitations, including potential biases in the data due to uneven geographic sampling and limited information on certain factors like poaching and persecution. The use of a space-for-time substitution to assess human development’s effects on carnivore populations may also not perfectly reflect the true dynamics. The complex relationships between different factors and their varying time lags require further research to fully understand their interactive effects. Finally, the lack of data from populations experiencing extreme habitat loss and climate change might lead to an underestimation of their true impacts.