HAWKS OF THE CANADIAN PRAIRIE PROVINCES. 7 



by the fact that they all occur in two colour phases, a dark one practically 

 similar in all four species and a light one more or less characteristic for 

 each. In each species all degrees of intermediates exist, making an 

 almost bewildering array of plumages. However, specific identity is of 

 little economic importance ap those most likely to be confused are 

 of similar status. In the dark phase the four species are dark brown or 

 nearly black, without any markings. Therefore, all black hawks can 

 be regarded as useful. 



The Red-tailed Hawk (length 20-24 inches) (Plate II B) is the 

 largest of American hawks excepting the two Rough-legs. It probably 

 weighs as much as either of these or perhaps more, but owing to its 

 closer feathering it usually appears to be smaller. In most characteristic 



Figure 1. Notched primaries (four) of Red-tail and Rough-leg. 



Figure 2. Notched primaries (three) of Swainson's Hawk. 



adult plumage it is brown above and white below with a rusty red tail 

 and more or less dark striping on sides of breast. As individuals tend 

 more towards the dark phase the dark flank and breast marks extend and 

 coalesce and the tail is barred with the same colour and often becomes 

 all brown with lighter bars. The typical light juvenile is all brown 

 above, including tail which is barred with lighter, and white below with 

 broad dark stripes on flanks and sides of breast. No reliable colour 



