Hybrid songbirds found more often in human-altered environments

Hybrids of two common North American songbirds, the black-capped and mountain chickadee, are more likely to be found in places where humans have altered the landscape in some way, finds new research. It's the first study to positively correlate hybridization in any species with landscape changes caused by humans, and the first to examine this relationship across an entire species' range -- spanning almost all of western North America.