326 BULLETIN 16 7, UNITED STATES NATIONAL MUSEUM 



Nicholson tells me that at every nest he has visited after dark he has 

 found both birds at the nest, one incubating or brooding and one 

 perched near it. In one instance the incubating bird remained on the 

 nest until the climber nearly reached it. Usually an eagle will leave 

 its nest as soon as an intruder is seen approaching it, but occasionally 

 one will sit closely until the tree is rapped. The food of the young 

 seems to be about the same as that of the adult, to be referred to later. 

 The behavior and development of the young will be discussed under 

 the northern race, on whicli more information is available. 



Plumages. — ^Wlien first hatched the downy young eaglet is com- 

 pletely covered with long, thick, silky down, longest on the head; it 

 is "smoke gi'ay" on the back, paler gray on the head and under parts, 

 and nearly white on the throat. When the young bird is about three 

 weeks old this light gray or whitish down is pushed out and replaced 

 by short, woolly, thick down of a dark, sooty -gray color, "hair brown" 

 to "drab." The pkmiage begins to appear on the body and wings, 

 scattered brownish-black feathers showing on the scapulars, back, 

 and sides of the breast, when about five or six weeks old ; at this age 

 the wing quills are breaking their sheaths. At the age of seven or 

 eight weeks the eaglet is fairly well feathered, with only a little down 

 showing between the feather tracks, and the flight feathers are fully 

 half grown. 



In fresh juvenal plumage the young eagle is uniformly dark col- 

 ored "bone brown" to "clove brown" above and below; the flight 

 feathers are nearly black, but there is usually a slight sprinkling of 

 gi'ayish white in the tail. This plumage is worn throughout the first 

 year without much change, except by wear and fading, the under 

 parts fading to "hair brown." After the first annual molt, the next 

 summer, the plumage becomes paler and much mixed with white in 

 very variable amounts. Individual feathers on the back, scapulars, 

 and breast are more or less extensively white, those of the breast and 

 belly being largely white in some specimens. I am not sure whether 

 this is a second or third year plumage, or both ; if the latter, the third 

 year is whiter than the second. The tail is more extensively mottled 

 with white than in the first year, and the feathers of the crown and 

 occiput are broadly tipped with pale buff. After the next annual 

 molt the plumage of the body becomes darker, much like that of the 

 adult, but lightly tipped with white below and mottled with white 

 on the rump and upper tail coverts; the latter and the tail are now 

 quite extensively white; the head is mixed with white above, about 

 half white and half brown, and nearly clear, dirty white below. This 

 is probably the third year plumage. At the next annual molt, early 

 in the fourth year, the bird assumes a plumage that is practically 

 adult, with a pure-white head and tail ; but usually remaining signs 



