Life-history type-based functional indicators mediate avian community responses to airport-associated disturbance gradients

Anthropogenic environmental changes can reshape animal spatial distribution at both species and community levels, yet how individual behavioral responses scale up to influence community-level succession remains unclear. To address this question, we propose the “disturbance gradient filtering” hypothesis, which posits that anthropogenic disturbance gradients act as an ecological filter for species with distinct life-history types, and test it using avian community data around three airports (Zhongchuan, Lintao, and Wuwei) with different bird repellency histories and frequencies. Two conventional diversity indices (Shannon and Simpson) and one life-history type-based index (AWM_PC1, abundance-weighted mean position of the first principal component of life-history traits along the fast-slow continuum) were calculated and regressed against the distance from airport across different airports and habitat types. Our results indicated that, relative to Shannon and Simpson indices, AWM_PC1 exhibited distinct patterns both in spatial variation across airports or habitat types and in spatial association with distance from airport. Spatial associations of AWM_PC1 were positive across habitat types at Zhongchuan, indicating that fast-lived species are more prevalent near the airport whereas slow-lived species become more abundant farther from the airport, while no such spatial trend was observed at Lintao and habitat-specific patterns were observed at Wuwei. Spatial associations of Shannon and Simpson indices followed a quadratic pattern at Zhongchuan and a linear pattern at Lintao, while no significant pattern at Wuwei. Our findings suggest that the strength and direction of community-level responses vary with both frequency- and distance-related disturbance gradients, and that life-history type-based indicators can effectively complement conventional diversity indices for interpreting these responses.