MOLTING PERIODS. 17 



dead mesoptile is carried on the tip of the growing teleoptile, as on the breast 

 of a marsh wren or towhee. Here the teleoptile tip is forced into the soft in- 

 ferior umbilicus of the mesoptile shaft which it expands and fills. Subsequent 

 or other feather molt is ordinary; the old feather, after a period of use, be- 

 comes loosened and falls out; or, as often happens where the insertion in the 

 skin is deep or strong, the now growth pushes its tip past the base of its pre- 

 decessor and eventually forces its loss, though in rare cases the two may 

 maintain themselves side by side for a considerable period. 



MOLTING PERIODS. 



At the close of the breeding season when the young are able to obtain 

 their subsistence, it is the rule, apparently with few exceptions, that the 

 parents immediately begin to change the old and usually very much worn 

 plumage. This new plumage may be like the old in color or very different, it 

 may be acquired quickly or may require a long time, comparatively. Some- 

 times the change occurs in migrating birds, before they leave their summer 

 home, in other cases it begins when the migration is over. The young also 

 undergo a fall change which is usually more complex than in the adults. The 

 change may be partial or complete and may be like the summer plumage as in 

 the male Black-throated Blue Warbler or very unlike the breeding plumage, 

 as in the Black Poll Warbler where the adult also acquires a plumage very un- 

 like the breeding one and which is renewed in the following spring on both. 

 A young male Hooded Warbler molts the gray body mesoptiles within a few days 

 after leaving the nest and acquires a new and strikingly different plumage, the 

 first teleoptile, of bright yellow and black, but it retains the mesoptile flight 

 feathers which as a migratory bird it carries to its (to us) winter home. Such 

 is the character of the change on many of our passerine birds, the period of 

 the uses of the mesoptile and first teleoptile featherings varying in different 

 species. 



But in some cases, as in the Cardinal, the change on the immature 

 bird is complete, the entire mesoptile growth, very similar to the adult fe- 

 male plumage, giving way rapidly to the first teleoptile, similar to the adult 

 plumage. In these last two species this highly colored adult plumage ac- 

 quired in autumn is retained until the close of the next summer and is the 

 breeding plumage of these males. In the Indigo, and Scarlet Tanager, how- 

 ever, the highly colored adult males molt in August into a greenish plumage 

 which is again changed in spring for the richer coloration, while the young of 

 the year assumes also the obscure fall plumage in which it winters and again 

 changes in spring into the richer condition, but rather imperfectly, for the 

 young indigo in its first spring has only an approach toward the full beauty of 



