Significance Connectivity, or the degree to which individuals can move across landscapes, is essential for species persistence and the maintenance of biodiversity. While connectivity is increasingly understood for some individual species and landscapes, understanding and predicting connectivity for entire communities remains elusive despite its importance for biodiversity theory and conservation practice. We address this long-standing problem by providing a framework based on allometric scaling, the relationship between morphology and organism traits. We apply the framework to a diverse community of birds using field experiments and observed data on dispersal and species distribution. Based on our framework, we are able to explain substantial variation in the observed bird community structure, highlighting how species traits related to movement can predict biodiversity across landscapes.