468 BIRDS OF ILLINOIS. 



Adult male (five specimens from Nevada, collected by the author). Total length. 21. 50- 

 23.00 Inches; extent, 49.00-63.00; weight, 2-3 pounds. Bill dull black terminally, 

 light bluish basally; cere and rictus greenish yellow; iris deep hazel in some specimens, 

 light yellow in others, in two specimens yellow on upper portion and brown below; legs 

 and feot light yellow ; claws black. 



Adult female (five specimens from Nevada, collected by the author). Total length, 

 23. 00-24. 00 inches; extent, 64.00-67.00; weight, 3-4 pounds. Fresh colors as In the above- 

 mentioned males. (Iris Naples yellow in one very black melanistic individual, deep 

 hazel in a rufous-breasted melanistic specimen, and hazel in three light-colored ex- 

 amples.)* 



The young bird of this western style is usually as different from 

 that of the eastern as is the adult, and the essential differences 

 are about the same, i. e. darker colors, or a predominance, or 

 rather, increase in size, of the dark markings. The numerous heavy 

 transverse spots on the tibiae constitute a marked feature of the 

 average young calurus, as compared with the almost, or sometimes 

 entirely, immaculate white of those in borealis. 



c. krideri. 



SUBSP. CHAE. Adult. Similar to borealis.but beneath continuous pure white, with- 

 out rufous tinge, and without distinct spots across the abdomen, or lacking them entirely ; 

 above much lighter, the brown, light rufous, and white being about eaual in amount. 

 Upper tail-coverts immaculate white; tail pale rufous, the shafts pure white, and the 

 webs mixed with white along their edges, its amount increasing toward the base ; no 

 trace of a dusky subterminal bar, or else only indicated by badly defined spots. 



"Young. Differing from that of var. borealis in the immaculate, snowy white lower 

 parts, nearly eaual extent of the white and dusky on the upper parts, and whitish cast of 

 the tail. 



This fine bird, although far less numerous than the Eed- 

 shouldered Hawk (B. lineatus) is yet very common in most por- 

 tions of the country. According to Mr. Horace A. King (in Orni- 

 tlwlogist and Oologist, Vol. IX., July, 1884, p. 81), "One of the com- 

 monest birds of prey to be found in northern Illinois, is the Eed- 

 tailed Hawk (Buteo borealis). A person will meet with them in all 

 sorts of places, but they are most common in the vicinity of heavy 

 timber. In driving through the country one will see them perched 

 upon rail fences, trees by the way-side, sitting on the ground in 

 stubble or pasture fields, or soaring over fields in search of their 

 prey. When on one of his foraging expeditions, the Eed-tail, on 

 sighting his prey, will remain at the same place in the air by a 

 continual flapping of the wings, when at the proper time he will 

 dive swiftly and silently upon it." 



* The color of the iris in this species (any race) Is very inconstant. In the fully adult 

 it may be either deep hazel, light hazel, light yellow, or partly brown and yellow; if the 

 latter, the yellow usually occupies the upper portion of the iris. In immature birds the 

 iris may be either clear light yellow, pale brown, or light grayish ; the first, however, ap- 

 pears to be the usual color. 



