1924] Swarth: Birds and Mammals of the Skeena River Region 337

Falco columbarius columbarius Linnaeus. Eastern Pigeon Hawk
Falco columbarius suckleyi Ridgway. Black Pigeon Hawk

The two subspecies of the pigeon hawk that are found in the region
are rarely to be distinguished in life, so that birds seen can be recorded
only under the specific name. Two pigeon hawks observed near
Hazelton on May 26 were presumably migrants; none was noted
during midsummer. The first fall migrant appeared August 22. and
from then on to the end of my stay (September 26) some were seen
nearly every day, sometimes several in one day.

The pigeon hawk is a remarkably swift flier, a fact borne out by
the stomach contents of one of my birds, the remains of a black swift
(Cypseloides niger borealis); That this hawk can capture a swift in
fair chase in the open is not likely (see Meinertzhagen, 1921, p. 237),
but after observation of both species I see no reason to doubt that on
occasion the swift could be taken unawares and caught by the hawk
after a short burst of great speed. This is in opposition to a possible
explanation that in the ease in question the hawk had captured a sick
or disabled bird.

Six specimens collected: one adult male, three immature males,
and two (presumably) immature females. This series is of interest
in its bearing upon the relationship of colwmbarius and suckleyt.
Not one of the lot is typical of columbarius, though I have so
labeled five of them (nos. 42050-42953, 42055), as most closely
resembling that subspecies. One female (no. 42054, Kispiox Valley,
August 29) is a typical, even an extreme, example of suckleyi. The
second female (no. 42053, Kispiox Valley, September 12) is nearer
true columbarius than any others of this series. The three immature
males (nos. 42050-42052), taken in Kispiox Valley on August 28, 22,
and 23, respectively, are intermediate in appearance between colwm-
barius and suckleyi, an intermediateness that is exhibited in a rather
curious way. Ventrally they are in color and markings practically
like columbarius, but dorsally they are quite as dark colored as the
average immature suckleyi. This same sort of intermediateness, that
is, light ventral and dark dorsal coloration, is also shown in an
immature female (no. 89762) from the lower Stikine River, British
Columbia, collected August 14, 1919 (see Swarth, 1922, p. 214), and
intermediateness both above and below is shown in an immature female
(no. 40371) taken near Coulterville, California, on December 20, 1919.

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