138 BULLETIN 142, UNITED STATES NATIONAL MUSEUM 



young, I was surprised to find that the supposed " mother," who had so valiantly 

 and zealously shielded " her " little ones, was actually father. I thought then 

 that perhaps the mother bird had been killed and that in the emergency the 

 father had assumed the responsibility for the youngsters ; but later I became 

 convinced by examination of many birds, that invariably it is the male that 

 cares for the fledglings after they are hatched. The female incubates the eggs, 

 but the male relieves her of further care in bringing up the family. 



Plumages. — In its natal down the young knot can be easily recog- 

 nized by the grayish, mottled colors on the upper parts and the 

 absence of browns and bright buffs. The shape of the bill, charac- 

 teristic of the species, is also diagnostic. The crown, back, rump, 

 wings, and thighs are finely mottled or spotted with black, white, 

 gray and dull " cinnamon buff," the last being the basal color. The 

 forehead, the sides of the head, the throat, and the entire under 

 parts are dull white, tinged with grayish on the flanks and crissum. 

 There is a broad median stripe on the forehead, a broad loral stripe 

 from the bill to the eye and a narrower rictal stripe of black. 



The juvenal plumage appears first on the wings, scapulars, and 

 sides of the breast; the primaries burst their sheaths before the 

 young bird is half grown. In the juvenal plumage, as seen on mi- 

 gration in August, the crown is heavily streaked with blackish 

 brow y n, the feathers being edged with light buff; the feathers of 

 the back and scapulars have an outer border of light buff, then a 

 black border, then another buff, and sometimes a faint black border 

 inside of that ; the greater and median wing coverts have a terminal 

 buff and a subterminal black border; the tail feathers are edged 

 with buff and the under parts are more or less suffused w T ith pale 

 buff. Probably the buff is brighter and deeper in fresh plumage 

 and it fades out to white before this plumage is molted. 



A postj u venal molt takes place, between September and December, 

 of the body plumage, some scapulars and some wing coverts. This 

 produces the first winter plumage, which is like that of the adult, 

 except for the retained juvenal scapulars and wing coverts. I have 

 seen birds in this plumage as early as September 30. A partial pre- 

 nuptial molt, similar to that of the adult, produces during the spring 

 a first nuptial plumage in which young birds can be distinguished 

 from adults by varying amounts of retained winter feathers. ■ At 

 the next complete molt, the first postnuptial young birds assume the 

 fully adult wunter plumage. 



Adults have a partial prenuptial molt between February and 

 June, involving most of the body plumage, but not all of the scapu- 

 lars, wing coverts, and tertials. There is much individual variation 

 in the time of this molt. I have seen birds in full nuptial plumage 

 as early as March 21 and in full winter plumage as late as May 13. 

 The complete postnuptial molt begins in July with the body molt, 

 which is usually completed before October. I have seen adults in full 



