Young Male Ruby-Throated Hummingbird in Flight

Not long after young hummingbirds leave their nests, they begin feeding along with the adults. After several weeks, the young males begin developing darker spotted feather patterns on the chin area below their necks. These spots form the foundation for the eventual emergence the characteristic red feathers on the necks of the male birds. I've read that these feathers are not actually red, but contain an absence of pigment that reflects the red color when full spectrum light shines on the feathers.