EASTERN HOUSE WREN 127 



Boulton (1927) has presented a detailed and exhaustive study of 

 ptilosis of the house wren in which his general conclusions are as 

 follows : 



The first appearance of feathers and the sequence of their development in the 

 varions regions follow in definite pre-determined order, constant for any one 

 region but varying among different regions. 



Development usually begins at one side or end of a region and spreads pro- 

 gressively over it until growth is completed. 



In at least one case (primaries), development begins in the middle of the region 

 and proceeds simultaneously toward each end. 



In another case (Ventral Tract), there are two centers of development. One 

 appears in the middle of the tract and spreads both posteriorly and anteriorly. 

 The other starts in the inter-ramal region and spreads backward until it meets 

 the anterior portion of the other development center. In the Spinal Tract is 

 found a somewhat parallel case. 



The feather sheath, after emerging from the skin, has no function and its rate 

 of disintegration is primarily correlated with the amount of abrasion to which it 

 is exposed. 



The growth of feathers appears to be retarded until the second week of nestling 

 life, but, to a large extent, this is actually due to the fact that development is 

 going on beneath the skin during the first week and is often overlooked, while the 

 rupture of the feather sheath and consequent exposure of the feather during the 

 second week makes growth appear more noticeably. 



According to Dwight (1900), 



the first winter plumage is acquired by a partial postjuvenal moult, beginning late 

 in August, which involves the body plumage and wing coverts, but not the rest 

 of the wings nor the tail. The young and old become practically indistinguishable. 

 [This plumage is] similar to the previous plumage but darker and grayer with 

 faint barring above, the wing coverts, chieflj'^ the lesser with whitish spots ; below 

 whiter without mottling, the throat and sides obscurely barred with pale drab, 

 the flanks and crissum boldly barred dull black which is bordered with russet. 



First nuptial plumage acquired by wear, excessive by the end of the breeding 

 season, which brings out the barring more conspicuously and makes the bird 

 grayer and paler, especially below. 



Adult winter plumage acquired by a complete postnuptial moult in August. 

 Practically indistinguishable from first winter, perhaps averaging grayer with 

 darker wings and tail. 



Adult nuptial plumage acquired by wear as in the young bird. * * * The 

 sexes are alike and the moults correspond. 



Albinism and melanism, which occur frequently in many families 

 of birds, is apparently rare in the Troglodytidae. Ruthven Deane, who 

 gave this subject a great deal of attention, knew of none and em- 

 phasized the absence of these plumages in certain families, including 

 the Troglodytidae. He offered no explanation for its absence. In a 

 search through the literature I have failed to find a single record of an 

 albinistic or a melanistic form of the house wren. Hence these phases 

 of plumage in this species are remarkable for their rarity if not their 

 absence. 



"Wetmore (1936) counted the number of contour feathers in various 



