78 
strongly marked and rufous below, especi- 
ally on thighs, and with more bars than 
the sub-terminal one on tail; melanisms 
are frequent, but they usually retain the 
rufous tail.+ 
+143d. Buteo borealis harlani? (Aud.), Bds. Am.,i., Lower 
pl. 86 (1830). [Near St. Francisville, Mississippi 
Louisiana, type in Brit. Mus.] Valley & Gulf 
Harlan’s Hawk. States, from 
Texas and 
Dark phase: resembling a melanism of Louisiana to 
B. borealis kridert; wing § 380, 2 400- Florida. 
408 mm. ; nearly uniform sooty-brownish- 
black, with much less of concealed white ; 
tail mottled with greyish, dusky and rufous, 
with sub-terminal black band. Light 
phase : resembling a small darker example 
of B. b. borealis. 
148e. Buteo borealis alascensis Grinnell, Univ. Cal. S.E. Alaska. 
Pub. Zool., v., No. 2, p. 211 (1909). [Glacier 
Bay and Chichagof I.] 
Alaska Red-tail. 
Resembling B. borealis calurus, but smaller 
throughout ; wing ¢ 344-355 mm. ; ° 365- 
370 mm.; dark areas blacker and more 
extended. 
143f. Buteo borealis costaricensis Ridg., Hist. N. Guatemala and 
Am. Bads., iii., p. 285 (1874). [Costa Rica.] Costa Rica to 
Central American Red-tail. Panama. 
1 I have examined the type of B. cooperi Cassin in the U.S. Nat. Mus. and am 
obliged to conclude it is an aberrant example of this form. 
2 Even after examination of a number of available specimens in the United 
States I am unable to discard this form as a melanism, since it seems to cover a 
definite geographical area and to be smaller than B. b. borealis. Light birds, such 
as those from Florida, with the rufous tail of B. borealis borealis, undoubtedly occur 
in its area, but they equal itin size. Melanistic birds referrable to harlani occur in 
Canada, Mr. Taverner assures me, within the range of krideri ; yet it is impossible 
to throw the range of harlani into that of kridert. 
