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SWAINSON’S BUZZARD. ni 283 
The species is thoroughly distinct from its nearest ally, B. bore- 
alis; it never gains the red tail, so characteristic of the latter, and 
differs in other points of coloration in its several stages of plu- 
mage, as noted beyond. Although its linear dimensions inter- 
grade with those of the red-tail, it is not so heavy nor so large a 
bird, and its shape differs in some points. A tangible and very 
convenient distinction, to which my attention was first called by 
r. Ridgway, and which I have verified in numerous instances, is 
found in the emargination of the primaries. As stated in my late 
work (Key N. A. Birds, p. 217), Swainson’s buzzard has only 
three emarginate primaries, while the red-tail has four; the fourth 
quill of the former, like the fifth of the latter, is variously sinuate- 
tapering, but never shows the decided nick or emargination of the 
The following measurements, taken in the flesh, illustrate the 
sexual difference and other variations in size: Largest adult Q 22 
inches long, 54 in extent, the wing 16; other females respectively 
21°50 51°75 K 16:25. . . 21°00 53°00 XK15°75. . . . 20°50 51° 
0015-25. . . 19:00 49-00 13:50; but this last one was an 
ungrown young. Adult ¢ 19-00 to 20-00 long, by about 49-00 
at spread of wing, the latter 15°00 and a little more. In bot 
sexes, and at all ages, the eye is brown, but of varying shade—I 
have seen no approach to a yellowiris. In the old birds the feet, 
together with the cere, gape, and base of under mandible are rich 
‘chrome yellow; the rest of the bill, and the claws, being bluish 
black. In the young of the year these yellow parts are much 
duller—grayish-yellow, or yellowish clay-color. Most of the old 
birds I have skinned had the integument of the lower belly largely 
bare, yellowish in color, hardened and thickened with warty ex- 
crescences ; this disease seemed the rule rather than the exception. 
nfledged nestlings are covered with white fluffy down ; the first 
feathers to appear on the under parts show the characteristic color 
and markings of the formerly supposed species, “ B.Bairdii.” 
(The various plumages are given beyond.) ° A moult occurs in 
August and September; it is protracted, the feathers being very 
gradually renewed, almost one by one; the fresh heavily colored 
feathers contrasting strongly with the ragged and faded ones 
worn during th summer. The young have no moult at this 
season, carrying aia plumage in which they leave the nest into 
the winter. I have no observations upon a spring moult which 
