18 
Plate II 
Butko borealis krideri 
and 
Buteo borealis calurus 
Diagrammatic representations showing characteristic body and tail colorations 
Figure 1. 1493 (Acad. Nat. Sei., Phila.) 6jv. Winnebago county, Iowa, September, 1872. 
Type of Buteo krideri Hoopes. Though this bird is exceptionally white it is obviously juvenile. 
Figure 2. 20(514 6jA r . Innisfree, Alberta, September 26, 1925. 
A well-marked krideri of same general type as above. It is obviously juvenile, still having 
down adherent to the tip of (lie tail. Note the decided tendency toward harlani pattern 
near base of tail. 
Figure 3. 10484 9 ad. Near Nevis, Alberta, July 9, 1917. 
Body that of normal borealis, hardly distinguishable from figure 5, but with characteristic 
white tail of krideri. Parent of next specimen. 
Figure 4. 10485 6 jv. nestling. Near Nevis, Alberta, July 9, 1917. 
Offspring of preceding. Note large amount of creamy white on head. 
Figure 5. 10454 9 ad. Near Red Deer, Alberta, July 4, 1917. 
A normal borealis, in body indistinguishable from figure 3, but with tail entirely different. 
The offspring of this specimen (No. 10453) only differs from figure 4 in having a little red 
in tail — about half-way between tail of figure 4 and that of figure 7. 
Figure 6. 1(3728 9ad. Oak lake, Manitoba, July 8, 1921. 
A rather light-coloured borealis with very white breast, and faint flank patches, but well- 
marked krideri tail. Note newly grown pin feather, suggesting the amount of fading to 
be expected in a season’s wear. Parent of following specimen. 
Figure 7. 1(3727 6 jv. nestling. Oak lake, Manitoba, July 8, 1921. 
Offspring of preceding, showing strong krideri body characters. 
Figures. 14112 6 ad. Tow hill, Graham island, Queen Charlotte islands, British Columbia, 
August 7, 1919. 
A dark, reddish calurus, typical of a type common in British Columbia, especially towards the 
coast, but which does not seem to be found on the prairies in breeding season. 
