“The National Geographic Guide to Birding in North America” S:1 E:9 Understanding Variations in Plumage

S:1 E:9 Understanding Variations in Plumage Plumage variation in a single bird reveals much useful information. First, take account of plumage differences based on sex, and seasonal plumage changes. Then investigate the remarkable range of age-related plumage variation in birds. Learn how birds molt (shed and replace plumage), and how hybrid species, as well as genetic and environmental factors, pose challenges for identification.