Socioeconomic variation across multiple cities predicts avian life-history strategies
Cities are the planets newest ecosystem and thus provide the opportunity to study community formation directly following major permanent environmental change. The human social and built components of environments can vary widely across different cities, yet it is largely unknown how these features of a city covary with the traits of colonizing species. We constructed a new dataset from open-source data with 44,670 observations of 160 Passerine species observed 1,908 urban areas across the United States. We found that as a citys housing density and median income increased it tended to support more migratory species and species with smaller body sizes and shorter lifespans. This suggests that differential survival and reproduction at the species-level can quickly generate geographical patterns of species trait variation across urban environments similar to those found in natural settings without the need for evolutionary change.