Winter range expansion of a hummingbird is associated with urbanization and supplementary feeding
Anthropogenic changes to the landscape and climate cause novel ecological and evolutionary pressures, leading to potentially dramatic changes in the distribution of biodiversity. Warm winter temperatures can shift species’ distributions to regions that were previously uninhabitable. Further, urbanization and supplementary feeding may facilitate range expansions and potentially reduce migration tendency. Here we explore how these factors interact to cause non-uniform effects across a species’s range. Using 17 years of data from Project FeederWatch, we examined the relationships between urbanization, winter temperatures, and the availability of supplementary food (i.e. artificial nectar) on the winter range expansion (more than 400 miles (700 km) northward in the past two decades) of Anna’s hummingbirds (Calypte anna). We found that Anna’s hummingbirds have colonized colder locations over time, were more likely to colonize sites with higher housing density, and were more likely to visit feeders in the expanded range compared to the historical range. Additionally, their range expansion mirrored a corresponding increase over time in the tendency of people to provide nectar feeders in the expanded range. This work illustrates how humans may alter the distribution and potentially the migratory behavior of species through landscape and resource modification.
This article was written by Emma I. Greig, Eric M. Wood, and David N. Bonter, and it appears in Proceedings of the Royal Society B. The Royal Society is in the United Kingdom and is possibly the oldest science society still in existence. Proceedings B publishes biological research and is one of two journals published by the society.