228 DWIGHT 



4. First Nuptial Plumage acquired apparently by wear 

 which produces Httle effect on the iridescent feathers, or possibly 

 by a complete prenuptial moult (if the postju venal is considered 

 as suppressed), as indicated by the specimens to which reference 

 has just been made. 



5. Adult Winter Plumage acquired by a complete post- 

 nuptial moult, after departure for the south. Probably indis- 

 tinguishable from first winter dress although I have seen no 

 birds identified as adults after the postnuptial moult. A speci- 

 men (Amer. Mus. Nat. Hist., No. 28100, 9, October 3d, Ari- 

 zona) is still in worn nuptial dress. 



6. Adult Nuptial Plumage evidently acquired by wear. 

 Female. — The sexes are practically indistinguishable in all 



plumages, although the female in nuptial dress is often if not 

 regularly much paler below than the male. 



Tachycineta bicolor (Vieill.). Tree Swallow 



1. Natal Down. No specimen seen. 



2. Juvenal Plum.\ge acquired by a complete postnatal moult. 



Above, including sides of head and neck, wings and tail sooty brown the tertiaries 

 . slaty with faint grayish edgings. Below, pure white, a very faint incomplete 

 sooty collar on the jugulum. Lores dull black. Bill dull black. Feet pink- 

 ish buff becoming dusky with age. 



3. First Winter Plumage acquired by a complete postjuve- 



nal moult beginning late in August and extending into October, 



as shown by large series, young and old becoming practically 



indistinguishable. 



Unlike previous plumage. Above, iridescent green, sometimes with steely blue re- 

 flections. Wings and tail deep bottle-green slightly iridescent, the tertiaries 

 broadly tipped with white. Below, pure white slightly smoky gray on the sides. 



A tertiary of this plumage is figured on plate II, fig". 6, and 

 the effect of wear ma}^ be seen by fig. 7. 



4. First Nuptial Plumage acquired by wear only obvious 

 in the entire loss of the white tips of the tertiaries, one of which 

 is figured on plate II, fig. 7. The wings become a trifle 

 browner as the summer advances. 



