6 
bers of the species, is not confined to them, and may occur throughout the 
more northern ranges, where a moister air and milder sun are less conducive 
to desiccation and fading. As for size, equally small birds can be obtained 
almost anywhere in the range of Buteo borealis. The points of distinction, 
therefore, seem too fine and inconstant to be dignified with subspecific 
recognition. 
GENERAL DISCUSSION 
All these forms, borealis, calurus, krideri, and harlani, so distinct from 
each other when typical, intergrade with each other in occasional specimens. 
Could well-defined, distinct distributions be ascribed to them, each would 
have to be acknowledged as good subspecies. Tracing the distribution 
of these forms, however, is particularly difficult. Very few of the pub- 
lished records of the several forms can be accepted without confirmation of 
specimens, as the general and often the technical public has had hazy or 
inaccurate ideas as to their distinctive characters. Such specimens as 
are in collections are mostly migrant or winter birds and useless for defining 
nesting ranges. 
Oologists have collected eggs of the species assiduously and should be 
in a good position to define the breeding range, but they who have been in a 
most favourable position to advance distributional ornithology have too 
often wasted their opportunities and have followed where they should 
have led. Instead of correcting current error they have largely been 
content to rubber-stamp the pronouncements of existing authorities and 
have in many cases perpetuated error instead of correcting it. Owing to 
the dearth of breeding material in collections and the above-mentioned 
uncertainty in published records, it has been necessary to rely largely 
upon the specimens in the National Museum of Canada in deciding racial 
characters and distributions. These specimens almost alone consist of 
any large proportion of breeding or moulting birds or of juveniles of demon- 
strable parentage. This series, although fairly complete for Canada, 
unfortunately does not represent more southern localities and an element 
of doubt exists, therefore, in statements referring to south of the Inter- 
national Boundary. 
The Red-tailed Hawk of eastern Canada, as far west at least as the 
Manitoba boundary, is typical B. b. borealis, though rarely, on migration 
dates in southern Ontario, specimens are found with krideri or calurus 
tendencies more or less pronounced. These may well be disregarded as 
erratic or stragglers. 
Throughout the southern parts of the provinces of Manitoba, Saskat- 
chewan, and Alberta the predominant bird seems to be borealis, usually 
with a slight tendency towards calurus, with numerous intrusives of krideri 
and occasional harlani specimens. The calurine tendency generally 
shows itself in the partial (sometimes complete) barring of the tail and 
flags, but melanotic or erythrismic birds or those with any marked tendency 
towards it are decidedly scarce in summer. They occur during migration 
and may possibly nest in the wooded country to the north. Dark birds 
have been reported there, but with other melanotic hawks (as swainsoni 
or even Archibuteo ) as probabilities the evidence is not conclusive. That 
melanotic birds do occur in at least parts of the prairie region is evidenced 
