PASSERINE BIRDS OF NEW YORK 97 



plumage at the prenuptial moult preceding their first breeding 

 season. The Baltimore Oriole (Icterus galbula) and Rose- 

 breasted Grosbeak (Habia ludcrvidana) are examples and in 

 these and many other species the renewal may not be complete 

 or the color may be deficient, producing tails that have been 

 said to be in process of " recoloration." When a young bird 

 acquires a new tail in autumn without moult in the remiges it 

 often suggests, either individual precocity or accident, for there 

 seem to be very few species in which this regularly occurs with- 

 out simultaneous moult of the remiges. Unilateral moult of a 

 few rectrices only generally indicates a mishap by which the 

 feathers have been pulled out and this is not an uncommon 

 accident. 



7. Lumbar, Femoral or Thigh Tracts (Pterylce hiuibales sen 

 fe morales). Two narrow bands, one on either side of the pos- 

 terior part of the back, form the areas from which the feathers 

 of the flanks grow, but the name flank generally applies to the 

 external lateral rows of the posterior extremities of the ventral 

 tract. The renewal in these tracts proceeds approximately from 

 above downward and from before backward, there being little 

 evidence of moult as a rule until the process is well under way 

 elsewhere. They are less often involved when there is a spring 

 moult than are the other body tracts and at this time may be 

 only partially renewed. 



8 . Crural or Leg Tracts (Pterylce crurales). The conto ur feathers 

 of these bilateral tracts are scattered, small and inconspicuous, 

 although most abundant near the tarsal or ankle joint. Their 

 moult easily escapes notice, beginning usually with the super- 

 ior and external feathers and ending among the closely imbri- 

 cated rows of the lower part of the tibiae or legs. The process 

 begins quite early and may be completed early. The failure 

 of these tracts, to moult when there is a general moult else- 

 where is frequent, especially with young birds in the spring, and 

 old feathers persist, noticeable chiefly when of a different color 

 from the new. These old feathers are often a valuable key to 

 the age of the bird. 



[ANNALS N. Y. ACAD. Sci., XIII, Aug. 3, 1900 7 



