112 D WIGHT 



The prenuptial moult is certainly a most interesting subject 

 and it is one upon which we have had very little light shed. 

 Its purpose is double, to approximate the plumage of the young 

 bird to that of the adult and to adorn the adult with his brightest 

 colors. In females the prenuptial moult is either limited or even 

 altogether suppressed, and a fresh complication arises in species- 

 in which it occurs only in the young bird, not to be repeated a 

 second year. Each species appears to have a definite type of 

 moult although individual vigor and sex modify it and produce 

 all sorts of combinations of plumage. 



Some species undergo a complete moult like the Bobolink 

 (Dolichonyx oryzivortis), Long-billed Marsh Wren (Cistothorus 

 palustris), or Sharp-tailed Sparrow (Ammodramus caudacutits) 

 others acquire distal primaries and part of the body plumage 

 like the Indigo Bunting (Passerina cyaned) or Short-billed 

 Marsh Wren (Cistothorus stellaris); others renew the whole 

 body plumage but not the wings or tail like many of the 

 Warblers, or the American Goldfinch (Spinus tristis); and still 

 others renew but a small area of the head and throat like the 

 Chipping Sparrow (Spizella socialis) or Palm Warbler (Dendroica 

 palmanwi). These are some of the classes into which the birds 

 naturally fall but there is no hard and fast line between them. 

 Ordinarily the anterior parts of the body are most frequently 

 subject to moult, the posterior parts less and the flight-feathers 

 least, but a few stray feathers are apt to develop on all of the 

 body tracts at this moult in presumably vigorous individuals. 

 The sprinkling of new feathers is well shown in such species as 

 the Summer Tanager (Piranga rubra}, and is only less con- 

 spicuous in the Palm Warbler (Dendroica palmaruni). From 

 what I have said it is obvious that the first nuptial plumage is 

 the most difficult of any to properly understand. It is the cul- 

 mination of the rapid series of moults through which a young bird 

 passes and in many species lands him in. full adult dress. When 

 adults and young appear to be alike in plumage in the breeding 

 season some clue to their age may often be found in the duller 

 and more worn wings and tail retained from the Juvenal stage of 

 the previous summer. The primary coverts are valuable keys 



