1926] Swarth: Birds and Mammals from the Atlin Region 109

on many occasions, and an old bird and one of its offspring were
secured, probably the first time that old and young of this form have
actually been collected. The young are distinctive and quite unlike
the young of calurus, the other dark colored form of Buteo borealis.
All this is corroborative of the theory that harlani is a ‘‘good’’
subspecies, in the sense of being a geographic race.

There is interesting evidence, of a negative sort, bearing upon the
migration route of the Harlan hawk, in the fact that in our series of
red-tails from the southwest, comprising about one hundred skins
from California, Nevada and Arizona, there is not one specimen
unequivocally of harlani. The only possible exception is an immature
female (Mus. Vert. Zool. no. 4094) taken at Julian, San Diego County,
July 27, 1908. This is a dark, blackish colored bird, like harlani in
shade of color, but it is peculiar in lacking any of the partly concealed
white spots and blotches that occur in that form. The uniformly black
color of this bird may well be explained on some ground other than
subspecifie identity with harlani.

The non-oceurrence of harlani in so large a series of specimens from
the southwest is strongly suggestive of the migration route of this
bird extending southeast from the breeding ground, crossing the Rocky
Mountains in the far northern portion of that range. This is the
route that is known to be traversed by many species that spend the
summer in the extreme northwest, and what is known of the winter
habitat of the Harlan hawk is corroborative of such a theory.

It is of interest to note that the red-tail (Buteo borealis alascensis
Grinnell) of the Sitkan district, Alaska, some one hundred miles to
the westward of the Atlin region, across the coast ranges, is of the
same general type of coloration as calwrus, to the southward, and shows
no approach toward the characters of harlani.

In the light of all the foregoing facts, a revised statement of the
range of Buteo borealis harlani might be worded as follows: Breeds
in extreme northern British Columbia, east of the coast ranges, north
into the valley of the Yukon, and eastward for an undetermined dis-
tanee. Migrates southward east of the Rocky Mountains, through the
Mississippi Valley to a winter home in the Gulf states.

While the bulk of evidence, as just given, is all corroborative of
this view, there are some opposing facts that should still be borne
in mind. The palest extreme of the red-tailed hawk, Buteo borealis
krideri, has been taken in the same general region, at Eagle, Alaska, in
winter (Bailey, 1916, p. 321), and on the Stikine River, breeding