It is thought that all young male Ruby-throated Hummingbirds develop their full red gorget on their tropical wintering grounds, so when they return to the U.S. and Canada in spring they look like typical adult males.
The male Ruby-throated hummingbird featured here did not migrate south in the fall, but instead overwintered in the Houston, Texas area. You can see he has an incomplete red gorget. Often overwintering males show slowed development - fewer red feathers and more throat streaking - until later in the spring. For these birds full male plumage is generally attained by early spring. Photo courtesy of Debra Repasz.