PASSERINE BIRDS OE NEW YORK 145 



Empidonax flaviventris (Baird). Yellow-bellied 



Flycatcher 



1. Natal Down. Brownish olive -green. 



2. Juvenal Plumage acquired by a complete postnatal moult. 



Upper parts, sides of head and throat, an obscure pectoral band, and lesser wing 

 coverts olive-green, the crown feathers centrally darker. Wings and tail deep 

 olive-brown ; median and greater wing coverts edged with rich buff yellow 

 forming two distinct wing bands, secondaries narrowly and tertiaries broadly 

 edged with yellowish white. Below, sulphur-yellow, including the orbital 

 ring. Bill black, the under mandible flesh. Feet dusky flesh-color. 



3. First Winter Plumage acquired by a postju venal moult 

 possibly complete after the birds migrate southward. Mid- 

 August specimens begin to show moult, the upper parts becom- 

 ing greener and the lower yellower, but others as late as Sep- 

 tember 24 and a few without dates of capture from Guatemala 

 and Mexico still bear the juvenal dress with the brownish wing 

 bands. 



4. P'lRST Nuptial Plumage acquired by wear. Young birds 

 are practically indistinguishable from adults, the wing bands ot 

 all early arrivals from the south being whitish, yellow tinged, 

 and the individual feathers little worn indicating a late postju ve- 

 nal moult. 



5. Adult Winter Plumage acquired by a complete post- 

 nuptial moult occurring probably late in the year after the birds 

 have reached southern latitudes. A specimen from Tehuante- 

 pec, Mexico, January ist (Am. Mus. Nat. Hist., No. 42940), 

 shows actual moult in progress of the body plumage and wing 

 coverts, the wings and tail being old and worn. This may, 

 however, be a young bird. Another bird from Panama (No. 

 42946), without date, shows moult of the body plumage. The 

 wing bands are new and faintly yellow in both, but they prove 

 little except a midwinter moult. 



6. Adult Nuptial Plumage acquired probably by wear 

 alone after a late autumnal or midwinter acquisition of new 

 plumage. 



Female. — The sexes do not differ in plumage nor in moult. 

 Annals N. Y. x\cad. Sci., XIII, August 27, 1900 — 10 



