Abstract
Biodiversity is experiencing an unprecedented crisis, with intensifying global aridity representing a critical driver of species extinction. However, the extent to which species' preferences for specific aridity conditions and their tolerance to a range of aridity conditions influence their vulnerability remains poorly understood. Using data from 5558 passerine bird species, we examined how aridity niche affects current and projected extinction risks and whether these relationships are influenced by other ecological and life‐history traits altering species persistence. Bayesian models revealed significant impacts of aridity niche position and breadth on both current and projected extinction risks, with these effects varying according to other species traits. Overall, aridity niche interacted with a wider range of traits for projected extinction risk than for current extinction risk, indicating a broader array of species requiring conservation attention in the future. Our results identified three key risk groups: (1) species preferring humid conditions, (2) species confined to arid zones with small clutch sizes, and (3) species with narrow aridity breadth and with low habitat breadth, short generation length, an omnivorous diet, and a full migrant strategy. By identifying passerine birds most at risk, our study offers critical insights for prioritizing conservation actions, guiding both geographic focus and the identification of species requiring more attention under the ongoing climate change.