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



Falco columbarius columbarius Linnaeus. Eastern Pigeon Hawk 

 Palco 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 horealis). 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 case 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 columiarius and suckleyi. 

 Not one of the lot is typical of columiarius, though I have so 

 labeled five of them (nos. 42050-42053, 42055), as most closely 

 resembling that subspecies. One female (no. 42054, Kispiox Vallej', 

 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 colum- 

 iarius and suckleyi, an intermediateness that is exhibited in* a rather 

 curious way. Ventrally they are in color and markings practically 

 like columiarius, 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. 39762) from the lower Stikine River, British 

 Columbia, collected August 14, 1919 (see Swarth, 1922, p. 214), and 

 intermediateness both aboA'e and below is shown in an immature female 

 (no. 40371) taken near Coulterville, California, on December 20, 1919. 



