88 COLOR AND SEASON 



in a plumage more like that of the female than of the adult male and 

 aequire their mature plumages at the first postnuptial (fall) molt. 



Less striking instances of failure to acquire a fully adult plumage at 

 the first spring molt are shown by birds like the Scarlet Tanager, which 

 at its first prenuptial molt retains most if not all the brownish wing- 

 quills and some of their coverts of its first winter plumage, the black 

 wing-quills of maturity not appearing until the first postnuptial molt; 

 or the American Goldfinch, which does not gain the yellow shoulder 

 patch until after the first breeding season. (Plate IV.) 



When the adults of both sexes are alike in color, the young in Juvenal 

 plumage more or less closely resembles them (e. g. Flycatchers, Jays, 

 Crows, most Sparrows, Chickadees, Thrushes); when the male differs 

 from the female, the young in Juvenal plumage more nearly resembles 

 its mother (e. g. Red-winged Blackbirds, Orioles, Purple Finches, Gold- 

 finches, Hooded Warblers, Redstarts). (Plate VI.) 



The juvenal plumage often gives interesting clues to relationships 

 and ancestry. The nestlings of the Blackpoll and Bay-breasted Warblers, 

 for instance, are almost indistinguishable, as are indeed the first winter 

 costume of these species; while the spotted breasts of nestling Robins 

 and Bluebirds betray their relationship with the Thrushes. 



Color and Season. Dull or inconspicuously colored birds, having 

 once acquired the plumage of maturity, exchange it only for another 

 of the same kind at their respective molts; but birds of striking colors 

 frequently change their bright breeding costume for one less likely to 

 expose them to danger while migrating. The male Scarlet Tanager, 

 for instance, at the postnuptial molt takes the olive-green body plumage 

 of his mate, only the black wings and tail coming in the same color 

 as before. At the same molt, the male Bobolink assumes a plumage 

 practically indistinguishable from that of his mate. With both birds 

 this dull plumage is worn until the prenuptial molt the following spring. 

 Other examples are the American Goldfinch, Bay-breasted, Blackpoll, 

 and Myrtle Warblers. (Plates IV, XX.) 



Among Gallinaceous birds the Ptarmigan alone have marked sea- 

 sonal changes in plumage, but in the Shore-birds, Gulls, Terns, and 

 Grebes, they are more or less pronounced. 



Here should be mentioned the various appendages like the plumes 

 of the Night Heron and Egrets, and crests or other head decorations in 

 the White Pelican and Grebe, which are usually acquired at the prenup- 

 tial molt and are worn only during the nesting season. 



Color and Sex. When there is a sexual difference in color among 

 birds, with few exceptions the male is the brighter. In North America 

 the exceptions are the three species of Phalaropes. No conclusive 

 reason why the male should be brighter than the female has been ad- 

 vanced. Darwin's theory of sexual selection endows the female with an 

 esthetic sense, making the most brightly plumed male more acceptable 

 in her eyes than his less effectively attired rivals. No one who has 

 watched a bird display its charms before the female (and this is done 



