Cornell Lab of Ornithology
Cornell Lab of Ornithology: A Calliope Hummingbird Molts Its Gorget Feathers
Striking photos are presented in this colorful site that show the molting stages of the Calliope Hummingbird.
Cornell Lab of Ornithology
Cornell Lab of Ornithology: Bird Feather Plumage Variations
Plumage variations can be based on a number of factors. This brief but informative examines single plumage patterns, seasonal variations, and sexual dimorphism.