36 COLOR AND AGE. Color and Age. — All birds have a special nestling plumage. With those that rim or swim at birth, such as Grouse, Snipe, and Ducks, this is a full suit of down, which may be worn for several w^eeks. "With those birds which are helpless when hatched — for instance, Robins, Sparrows, and Orioles — this downy covering is so scanty that they are practically naked. This birth dress is followed by a new growth, known as the " first plumage." Down-covered birds do not acquire this for some time, but with those birds that are born nearly naked it begins to grow soon after they are hatched, and is almost complete when they leave the nest. The first plumage is often unlike that of either parent; for ex- ample, the spotted plumage of the Robin. It is worn for several months by some species — certain Snipe and others — but with most land birds it is soon exchanged for the costume they will wear through the winter, usually termed the "immature plumage." This may resemble that of either parent respectively — that is, immature males may be like adult males and immature females like adult females, as with the Bob-white and Cardinal Gros- beak; or the immature birds of both sexes may resemble the adult female, as with the Hummingbird and Bobohnk. Again, the immature birds of both sexes may be unlike either of the adults, as with the Eagle and most Hawks; or the immature female may resemble the adult female, while the immature male is unlike either parent, as in the case of the Rose-breasted Grosbeak and Scarlet Tanager. When both parents are alike, the young generally resem- ble them, and this happens among most of our land birds; for example, the Flycatchers, Crows and Jays, many Sparrows, Vireos, Wrens, and Thrushes. Immature birds, differing from the adults, may ac- quire the adult plumage the next spring, as with the Bobolink, or they may then don a second or transition
