Cities, suburbs, roads, buildings, and landscaping shape the world in which we live. This development can harm vulnerable species or break up migration routes. But not every species is impacted the same way. New research finds that a common, adorable songbird is a subtle barometer of human activity.
A University of Colorado study finds that human cities and towns cause chickadee species to hybridize. If humans build towns where ranges of mountain chickadees and black-capped chickadees overlap, those species produce hybrids.