FALCONID^E — THE HAWKS — BUTEO. 471 



during the nesting season. Their nests are numerous in the valleys and on 

 the lower mountains. They are generally luiilt in the forks of a syca- 

 more or other large tree, and formed of twigs, pretty firmly constructed, 

 and with a distinct cavity, nnlike the vultures. The eggs I found near 

 San Diego, laid about ]\Iarch 2(lth, were three in number, measuring 

 2.28 X 1-76 inches, and dull yellowish-white, with faint brown spots. On 

 my climbing to the nest tlie old birds darted towards me from a neighbor- 

 ing bluif, but when within a few feet of my head they turned away, and 

 did not attempt to make an assault upon me. 



They prey on rabbits and tlie smaller animals, including lizards, and occa- 

 sionally seize a fowl from the farm-yard. They usually become very fat, 

 especially where squirrels are numerous, and spend hours in sitting stupidly 

 on some tree, dozing while they digest their food. They also soar high into 

 tlie air during tlie middle of the day, sometimes in large numbers during 

 the cold months, occasionally rising to so great a height as to disappear 

 entirely. 



The Eastern red-tailed hawk is so similar, that sometimes the differ- 

 ences are scarcely appreciable, but, according to Cassin, it may be dis- 

 tinguished by smaller size (19.00 to 24.00 inches long; wing, 1400 to 16.00; 

 tail, 7.50 to 8.50), also by whiter under parts, fewer spots below, and fewer 

 bars on tail in the young. Dr. Bryant considers them the same, but the 

 majority of Western and Eastern specimens differ as above described. A 

 specimen from Fort Mojave, Colorado Valley, may perhaps belong to this. 



Buteo calurus, C.\ssin. 



THE KED-TAILED BLACK HAWX. 



Biileo aihirus, Cvssix, Pr. A. N. Sc. riiil. VII. 18,5.'j, 2SI. Ib. P. R. Rep. Birds, IX. 22. — 

 Bairi), X. iii. II ; pi. xiv. — CouES, Pr. A. X. 8c. 1S66, 4.'!. 



Sr. Cii.\R. Entire pliimaf^e of boily l)ri)wnisli-black, deeper anil dearer on back and 

 abdomen, paler on throat and breast. Above with concealed transverse bands of white at 

 the base of feathers, beneath also, with circular white concealed spots ; quills brownish- 

 black, with a large portion of their inner webs white, banded and mottled with pale ashy- 

 brown ; under tail coverts transversely barred with brownish-black and pale rufous. Tail 

 bright rufous above, white at base, with eiplit or ten irre<iular and iiujicrt'cct narrow banils, 

 and one subterminal wider band of brownish-black, narrowlv ti|ipiMl with reddish-white ; 

 beneath silky reddish-white. 



Young, duller brown above and below ; tail brown with ten or twelve narrow transverse 

 bands ; ashy below. Primaries white at base, black at end. 



Length, 21.00 to 22.00 ; extent, 48.00 to 53.00 ; wing, 16.50 to 1 7.50 ; tail, 9.00 to 10.50. 

 Iris brown ; bill horn-color ; cere and ii-et }ellow. 



//(///. \ew Mexico and Califiiniia. 



