138 
NORTH AMERICAN BIRDS. 
Adult. Lower parts deep dark rufous, almost free from bars, except 
posteriorly. Young. Dark spotting on the lower parts pre- 
dominating. Hab. Pacific Province, and southern Western Prov- 
ince, of the United States. {Western ^Red-shouldered Hawk.) 
var. el eg a ns. 
b. Form robust and heavy, the tarsus , stout ; tail of the adult with a sub- 
terminal band of black broader than the other. 
5. B. borealis. Wing, 13>25- 17.75; tail, 8.50-11.30; culmen, .90- 
1.15; tarsus, 2.70-3.40; middle toe, 1.60-1.95. Weight, 2-| to 4 pounds 
Third to fifth quill longest ; first shorter than seventh and shorter than 
tenth. Colors extremely variable, ranging from entirely pure white 
beneath, through various shades of ochraceous and rusty, and greater' 
or less amount of darker spots and bars, to an entirely uniform brownish- 
black. Adult. Tail deep rufous, generally paler at the tip ; with or 
withotit black bars. Young. Tail grayish-brown, crossed by nine or 
ten bands of blaek, much narrower than the gray ones. Lower parts 
always with white predominating. 
Tibiae and lower tail-coverts without transverse bars, at any age. 
Lower parts with white always predominating. Tail never with 
more than one bar of black. 
Feathers of the head and neck edged laterally with rufous ; 
scapulars and wing-coverts much variegated ‘with whitish ; 
upper tail-coverts white, barred with rufous. Throat with 
blended streaks of blackish, this usually predominating ; tibiae 
and lower tail-coverts plain yellowish- white. Hab. Eastern 
Province of North America, to the Missouri plains. {Red- 
tailed Hawk.) ....... var. borealis . 
Similar, but colors much paler, the lower parts entirely pure 
white, with little or no spotting on the abdomen. Tail usually 
destitute of the black subterminal band. Hab. Plains, from 
Texas to Minnesota. {Krider's Red-tail.) . . var. krideri. 
• Similar to the last, but lower parts strongly tinged with 
rufous on the tibiae, and upper parts much darker. Tail 
always destitute of the subterminal black band. Young not 
distinguishable from that of var. calurus. Hab. Cape St. 
Lucas. {Lucas Red Aail.) .... var .lucasanus. 
Whole head, neck (except the throat), and upper parts, con- 
tinuously uniform unvariegated brownish-black ; that of the 
neck meeting narrowly across the lower part of the throat, 
leaving the whole throat almost immaculate white. Posterior 
; lower parts fine, deep pinkish-ochraceous ; tibiae deep reddish- 
ochraceous; upper tail-coverts plain rufous. Hab. Central 
America (from Tres Marias, Western Mexico, to Costa Rica 
and V eragua) . ( Costa Rica Red-tail.) . var. costa ficensis* 
Tibiae and lower tail-coverts always with distinct transverse bars. 
Tail often with more or less complete transverse bars of black to 
the base. Lower parts with an excess of ochraceous and darker 
markings, frequently wholly blackish. 
Yarying, from individuals distinguishable from the darker 
examples of var. borealis only by the presence of bars on the 
tibiae and crissum, through others with various degrees of 
rufous tinge and dusky spotting and barring beneath, to a per- 
-£ ,v -v. 
