Millions of birds travel between their breeding and wintering grounds during spring and autumn migration, creating one of the greatest spectacles of the natural world. These journeys often span incredible distances. For example, the Blackpoll warbler, which weighs less than half an ounce, may travel up to 1,500 miles between its nesting grounds in Canada and its wintering grounds in the Caribbean and South America.
For many species, these journeys take place at night, when skies typically are calmer and predators are less active. Scientists do not have a good understanding yet of how birds navigate effectively at night over long distances.
We study bird migration and how it is being affected by factors ranging from climate change to artificial light at night. In a recent study, we used millions of bird observations by citizen scientists to document the occurrence of migratory bird species in 333 U.S. cities during the winter, spring, summer and autumn. MORE
Header image: Blackpoll warbler. Credit: PJTurgeon/Wikipedia.