16 Bkewster's Descrijitions of the First Plumage 



sion that has previously resulted either from misapprehension, or 

 from a too free use of certain distinctive terms. 



While it is to be regretted that the specimens at hand do not 

 furnish full series of even all the commoner species, it is nevertheless 

 hoped that, by calling attention to this hitherto neglected field, an 

 impetus will be given to future investigation that may result in a 

 more complete knowledge of the subject than can here be presented. 

 Before proceeding to a detailed consideration of specimens it may 

 prove of interest to state briefly a few generalizations regarding the 

 comparative development of the young in different families of 

 birds. 



Among North American Altrices the young of most species are 

 born with thin patches of delicate, soft down, restricted mainly to 

 the feather-tracts. Beneath this fluffy down the feathers are 

 already forming ; these soon appear, bearing at their summits the 

 little tufts of down that formed the down-patches. Meanwhile the 

 remiges and rectrices have started, and, growing with marvellous 

 rapidity, the bird is soon able to take wing. The contour-feathers 

 have now also nearly reached their full growth, and differ in both 

 structure and color from the later stages of plumage, these feathers 

 being softer and of a more open texture than those that succeed 

 them. This is the stage of plumage technically characterized 

 throughout the following paper as the first 'plumage. Though eva- 

 nescent, it is usually worn for several weeks after the bird has left the 

 nest. It is then moulted, and the regular autumnal plumage suc- 

 ceeds. 



The remiges and rectrices are, however, nearly always retained 

 until thf next regular moult, exceptions to this rule being afforded 

 by the families Tetraonida and Picidce and the genus Pkilohela, 

 and probably by a few other groups, in which the remiges and rec- 

 trices are moulted with the rest of the first plumage. 



The early tegumentary development of most Pracoces (birds 

 whose young run about at birth) is quite different : they are 

 densely clothed with down until of large size, when, coincident with 

 the sprouting and growth of the remiges and rectrices, the feathers 

 of the full autumnal plumage appear. In short, the first plumage 

 of Altricial birds seems to be omitted or perhaps replaced in the 

 Pr&coccs by their more complete and longer worn, downy plumage. 

 A few conspicuous exceptions occur among both groups. Thus, 

 many Itaptores differ from the Altrices in being densely clothed with 



