Assessment of increase in the abundance of two hummingbird species in the last decade in Mexico City

Abstract

Hummingbirds are nectarivorous birds with a very fast metabolism, which requires constant access to resources. In cities, resources have distinct abundances and availability from natural environments, which leads to the exclusion of some species. However, other species may increase in abundance within cities, causing a process of biotic homogenization. In this work we evaluated whether the abundance of five resident hummingbird species has increased in Mexico City over the last decade. Additionally, we evaluated whether these hummingbirds used feeders throughout the year. Finally, we determined the reproductive season of hummingbirds and evaluated whether it is longer in Mexico City than in non-urban locations. Our results indicate that during the last decade, the abundance of Berylline Hummingbird and Broad-billed Hummingbird has increased in Mexico City. Both species take advantage of the feeders throughout the year. This constant availability of resources has allowed both species to extend their breeding season, leading to constantly increasing abundance. One way to avoid biotic homogenization in cities is to implement conservation strategies that include variations in the availability and abundance of native floral resources such as pollinator gardens, rather than constantly available artificial resources like feeders.