Climate and human impacts on the dietary niche overlap of sympatric livestock and wild ungulates.

As anthropogenic activities continue to expand globally, large-scale livestock encroachment into wildlife habitats increasingly threatens ecological balance, particularly by altering species interactions. Millions of wild ungulates now share plant resources with domestic grazers, facing dual pressures from interference competition and nutritional stress due to declining forage quality. Although extensive research has documented potential competition between sympatric wild and domestic ungulates, a comprehensive quantitative synthesis of the magnitude and drivers of these interactions remains lacking. In this study, we conducted a meta-analysis of 57 peer-reviewed studies (329 cases) to evaluate global patterns of dietary niche overlap between wild ungulates and livestock. Our results revealed that both wild ungulate traits and livestock type significantly influenced the effect sizes. Moreover, climate zones, annual precipitation, and interactions with anthropogenic pressures modulated livestock-wildlife dietary niche overlap. Polar regions and large-bodied species exhibited heightened sensitivity to human activities, while areas with higher annual precipitation showed reduced variation in dietary niche overlap intensity. These findings suggest that wildlife-livestock dietary niche overlap is shaped by multiple factors. While additional factors beyond dietary niche overlap should be considered in conservation assessments, our results suggest several potential management strategies including reducing anthropogenic disturbance in polar regions, integrating grazing management with efforts to reduce human disturbance in large ungulate habitats, and adjusting livestock composition and supplementary feeding in moisture-deficient and tropical regions. Future conservation assessments should integrate dietary overlap shifts with other conservation risks for a more comprehensive evaluation.