SWAIIsrSON'S HAWK 227 



out the first year with no change except by wear and fading; the 

 buffy edgings above wear away and the biiffy tints below fade out 

 to pure white. The sexes are alike in this plumage. 



Subsequent molts and plumages are quite puzzling and very much 

 complicated by the three color phases and their intermediates, as 

 well as much individual variation and some slight sexual differences. 

 Coues (1874) recognized only a first-year and an adult plumage in 

 light-phase birds ; he noted a melanistic phase but not the erythristic 

 phase. E. S. Cameron (1908a and 1913), who made a careful study 

 of this subject and raised birds in captivity, describes four successive 

 plumages of each sex and states that this bird does not become fully 

 adult until the fifth year. This would be a decided departure from the 

 procedure in other Buteos. A study of his descriptions suggests that 

 he confused individual variations and seasonal changes with pro- 

 gressive age developments. 



I can recognize only three plumages in the normal or light phase, a 

 first-year, a second-year, and a third-year, which is practically adult 

 but perhaps subject to some modification with advancing age. To- 

 Avard the end of its first year the young hawk begins to molt from the 

 first-year into the second-year plumage. This molt is probably com- 

 plete, but very irregular and quite prolonged. It begins with the molt 

 of the primaries and tail in April or May, continues with the body 

 molt during summer, and is not completed until September or later. 

 I have seen a bird in worn first-year plumage as late as September 9, 

 which was probably over 15 months old. 



In the second-year plumage the sexes begin to differentiate, and the 

 color phases, which I have not been able to recognize in first-j^ear 

 birds, become evident. In light-phase birds the chin and throat are 

 white, more or less streaked with dusky, and sharply contrasted with 

 the breast band, which is acquired with this plumage; this breast 

 bsnd is much like that of the adult "tawny" to "russet" in males and 

 "drab" to "hair brown" in females, while the belly and tibiae are more 

 or less barred, spotted, or clouded with "tawny", "russet", "hazel", 

 or "warm sepia" in a variety of shades and patterns in different indi- 

 viduals ; females are more heavily marked than males ; birds that will 

 eventually develop the melanistic phase are much darker and more 

 heavily marked at this age; and a tendency toward the erythristic 

 phase may be indicated by a preponderance of reddish shades. The 

 feathers of the mantle have buffy edgings fading later to white. 



Coues (1874) included the above in the variable adult plumages, 

 and Mr. Cameron (1913) regarded it as a third-year plumage; but 1 

 cannot agree with either, though their remarks are well worthy of 

 study. 



At the next summer molt, when two j^ears old or more, the bird 

 assumes a plumage that is practically adult and much lighter every- 



