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 as 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 Ited-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 
