52 LIFE HISTORIES OF NORTH AMERICAN DIVING BIRDS 



belly portion is white, tinged laterally with grayish. I have not been 

 able to find any specimens showing the change from the downy stage 

 into the first winter plumage. The latter, however, is well repre- 

 sented in collections and is well marked; it is chiefly characterized 

 by the well-rounded feathers of the back and scapulars which are 

 broadly edged with gray or whitish; the top of the head, hind neck, 

 and rump are blackish or sooty, grading off gradually on the sides 

 of the neck into the fine dusky mottling of the throat; the chin, some- 

 times the throat and the underparts are white. This plumage is 

 worn for nearly a year without much modification, the light edgings 

 above bleaching out to white or wearing away and the throat becom- 

 ing whiter toward spring. The bill is horn colored in the fall, be- 

 coming darker in the spring, but never black. Probably there is an 

 incomplete prenuptial molt. The postnuptial molt is complete and 

 produces early in the next fall the second winter plumage, which is 

 similar to the first winter plumage except that the dark crown is 

 more clearly defined, the throat is pure white and the feathers of the 

 back, which still have broad light edgings, are less rounded and more 

 nearly square at their tips. This plumage is worn for only a short 

 time in some individuals which begin to show signs of molt into the 

 second nuptial plumage as early as November or December, by the 

 growth of a few of the jet-black feathers with white spots on the 

 back, wings, rump, and flanks ; usually this molt is not much in evi- 

 dence until February; from that time on the prenuptial molt ad- 

 vances to the head and neck and by April or May the second nuptial 

 plumage is completed. This is similar to the adult nuptial plumage, 

 but is duller, more dingy, and often incomplete, with more or less 

 white in the chin and throat. Specimens in this plumage have been 

 found to have the sexual organs somewhat enlarged, indicating that 

 the birds probably breed when about 2 years old. The bill is now 

 black and never again becomes as light colored as in young birds. 

 At the next postnuptial molt the young bird becomes fully adult, 

 when a little over 2 years old. , 



The adult winter plumage, assumed during the third fall, is char- 

 acterized by the black bill and by the square tipped feathers of the 

 back and scapulars, which have no light edgings but have a faint 

 suggestion, a ghost as it were, of the white spot of the nuptial plum- 

 age in a shade of gray only slightly lighter than the rest of the 

 feather. This plumage is worn for only a short time, as in the second- 

 year bird; specimens in this plumage are very scarce in collections and 

 it is difficult to find one that is not either molting into it or out of 

 it; the postnuptial molt into it begins sometimes by the last of August, 

 but sometimes not until October; and the prenuptial molt out of it 

 may begin in November or later in the winter and may not be com- 

 pleted until spring. Apparently some individuals, perhaps very old 



