Pathways to city dominance: the urban ant syndrome

Ants are among the most ubiquitous animals in cities, yet only a small subset of the world's ant fauna consistently thrives in urban environments. Despite the prominence of ants in urban ecosystems, we lack a cohesive framework for understanding why certain species succeed while others decline. Here, we synthesize emerging research to describe an 'urban ant syndrome,' or a modular set of behavioral and ecological pathways that enable ants to overcome the characteristic challenges of human-built environments. We first develop a functional definition of 'urban ants,' distinguishing true urban exploiters from species that merely occur within city boundaries. We then describe three domains in which successful urban ants repeatedly exhibit convergent strategies: (1) life history, including supercoloniality, polydomy, and budding dispersal; (2) thermal biology, particularly the use of urban heat for foraging, survival, and brood development; and (3) nutritional ecology, characterized by reliance on high-carbohydrate anthropogenic foods or mutualisms with honeydew-producing insects. While no species expresses all pathways, consistent combinations emerge across continents, including in native species that evolve urban-specialist traits. Understanding these shared strategies provides a predictive foundation for identifying future urban dominants and for managing ecological outcomes in increasingly urbanized landscapes.