110 University of California Publications in Zoology [Vou.30

(Swarth, 1922, p. 212). Bishop (1900a, p. 73) speaks of the red-tails
of the Yukon region (referred to B. b. calwrus) as being in both the
light and the dark phase, about half of each, and of light colored and
dark colored birds breeding together. Nothing of the sort was seen in
the Atlin region, which may indicate that while harlani alone occurs
in that section, it has a relatively limited range. I did see one pale-
colored bird, apparently krideri, near Gladys Lake, but this was on
September 7, when the southward migration was going on, and many
hawks were seen passing southward overhead.

Both as regards different color phases and geographic variation,
the coloration of the Buteo borealis group (as well as of some other
species of hawks) is admittedly a difficult subject, and one that is
still far from being understood by any one. The most I can claim
for the facts here adduced is that they are corroborative of the idea of
Buteo borealis harlani being a geographic race rather than a ‘‘color
phase,’’ such as is the darkest type of coloration seen in B. b. calurus.

_ These dark-colored Buteos were seen by us almost daily through
the summer and in all parts of the region that we visited. On May
21 several were observed soaring low over the snow-covered slopes on
the east side of White Pass. During the next week, at Carcross, they
were seen daily; apparently several pairs were settled on their nesting
grounds near the town.

About Atlin these hawks were distributed throughout the lowlands;
there were nesting pairs at intervals of a few miles in whatever direc-
tion one traveled. Although the species was thus relatively numerous,
specimens were hard to obtain; the birds were remarkably wary.

The Harlan hawk is in the Atlin region mostly a bird of the timber.
The sort of perch most often chosen is the top of one of the taller
spruce trees, often in fairly dense woods but always with such a com-
manding view as to make approach unseen out of the question. With
the exception of the dark colored hawks seen in White Pass early in
the season and supposed to be of this species, none was observed in
the open country above timber line. The abundance of ground
squirrels might have been supposed to be an attraction to that region,
too. They were extremely wary always, so much so that although
both birds of a pair might circle about, screaming, as long as an
intruder remained in their territory, it was generally impossible to
approach within gun shot.

One nest was found. It was in the valley a few miles from Atlin,
in rather open spruce woods, just above a stretch of marsh land. The