Most adult birds are covered with feathers except on the beak, eyes, and feet. A follicle ordinarily produces a series of feathers during a bird's life. If the bird molts, the new feather pushes out the old one. If a feather is lost some other way, the follicle replaces it immediately or at the next molt, depending on the time of the next molt, the health of the bird, its reproductive state, etc. The number of feathers is relatively constant within a species although they tend to have more feathers in the winter than in the summer.
Smaller birds tend to have more feathers per area than larger birds although fewer feathers total.
Juvenal Plumage - this plumage is composed of the first true contour feathers. Tends to be loosely textured, giving the bird a fuzzy appearance. Passerine birds develop this plumage before they leave the nest. First Nuptial Plumage - this may be the same, partly different, or wholly different than the first winter plumage. Retained during the breeding season.