BUTEO CALURUS. 58;{ 



the cotton-woods of the Truckee and Cavson Valleys, where we found it 

 (luite unsuspicious and easily killed. During the summer it was nnich less 

 abundnnt in the lower valleys than Swainson's Hawk, but it was more 

 (•(innniin on the monntisins, partit'ularly in the pine f(.)rests. (.)n the V/ah- 

 satch, we saw several of its nests on tall i)ine trees or on ledges of the cliifs, 

 most of them being inaccessible, in which respect this species differs con- 

 spicuously from the 1j. sini'uisoiii, which in the same region was found to 

 build its nest on the top of the scrub-oaks or in the small aspens, within 

 easy reach. 



The series of specimens in the collection exhibits the usual individual 

 variatinu so remarkable to the \vestern birds of this species, there Ijeing 

 examples so light-colored as to be scarcely distinguishable from the typical 

 eastern B. horcalls, while one is of an almost uniform deep sooty-black, the 

 others being variously intermediate. As was the case with B. swaiiisot/i, the 

 light and dark individuals were often found paired.^ 



List of .specimens. 



132, 9 ad. (melanotic, very blacJcJ; Big Beud of the Truckee (Camp 12), Nevada, 

 August 17, 18G7. 234—54— lOi (inoltiug). Bill, slate-black, the basal half of the 

 lower niiuidible blnish-slate; cere, dull .yellowish green, i)urest on top; rictus, more 

 yellow; iris, muddy uaplcs yellow ; tarsi and toes, dull pale greenish-yellow; claws 

 "black. 



337, 9 ad f melanotic, rvfovs-hreasted stylcj; Genoa, Nevada, November 29, 1SG7. 

 23i— 55— 17— 14— 1^'g — 2— 9:^— 5^. Weight, 3J pounds. Bdl, dull black, passing into 

 pale bluish basally ; cere and rictus, light dull ashy-green ; iris, deep hazel ; tarsi and 

 toes pale dull naples-yellow ; claws, black. 



347, S ad.; Truckee Reservation, December 19, 1807. 2rj— jlj—lij- l.'Ji- li— 

 (?)_9_5. Weight, 2 pounds. Bill, dull black, fading into duU.light bluish basally; 

 cere and rictus, dull greenish-yellow; iris, deep light hazel; tarsi and toes, very dull 

 light chrome-yellow, deeper beneath. 



3rA,gad.; same locality, December 11, 1SC7. 2U— 49— 15g— 12.^— 1,',— (?;— 9;^ 

 — 5i. Weight, 24 pounds. Bill, black, fading basally into light horn-drab; basal half 

 of the lower mandible, pale blue; cere and rictus, clear light yellowish-green; iris, 



1 There being many who yet hold the old belief that this dark phase, found in so 

 many species of Falconidse, is in some manner dependent ou ae/e, we wish to iini)ress 

 our readers with the fact that it is a purehj indiridiinl condition, entirely independent of 

 aye, .<icx, or season; it is properly styled vielani.im, and is analogous to the condition of 

 crythrism in certain owls. In every American species which has this fuliginous plu- 

 mage, the dark birds are dusky from the nest up ; while those in light plumage never 

 assume the dark dress. This is probably the case with the Old World species also. 



