174 BULLETIN 16 7, UNITED STATES NATIONAL MUSEUM 



BUTEO BOREALIS HARLANI (Audubon) 

 HARLAN'S HAWK 



HABITS 



Harlan's hawk has always been regarded as a subspecies in the 

 Buteo hm^ealis group and is so recognized in our latest A. O. U. 

 check-list (1931). James L. Peters (1931), in his new check-list, 

 treats it as a full species, and several good ornithologists agree with 

 him. I am inclined to accept this view, because the chief character 

 of harlani^ the mottled tail of the adult, seems to be a qualitative 

 rather than a quantitative character, I shall not attempt to discuss 

 here, or come to any conclusion regarding, the status of the many 

 })uzzling hybrids or intermediates that have been shown to exist, 

 but shall merely try to present some of the facts and some of the 

 theories. 



P. A. Taverner (1927) has made some extensive studies of the 

 horealis group and has published an excellent paper on the subject, 

 beautifully illustrated with colored plates. He has suggested that 

 harlani is a color phase of calurus, and that krideri is a color phase 

 of horealis^ stating that '''■krideri occurs along the western boundary 

 of the horealis range and harlani at the northern extent of calurus 

 territory, neither having any centre of distribution where they occur 

 in purity." This seems like an untenable theory and to be based on 

 incorrect premises, for it is a well-known fact that pure krideri 

 occupies quite an extensive breeding range on the prairies and plains 

 of the Midwestern States; and Harry S. Swarth (1926) says of 

 Jmr'lam., in the Atlin region of northern British Columbia : "The 

 birds were abundant and nesting ovei^ a wide expanse of territory, 

 and within that region they were the only form of Buteo horealis 

 that was seen." 



Recently, Mr. Taverner (1936) has published another paper on 

 the complicated relationships in the Buteo horealis group, to which 

 the reader is referred for his latest views on the subject. Dr. Louis 

 B. Bishop has also made quite an extensive study of this group, 

 based on his large collection of the various races and on his study 

 of other collections, and does not wholly agree with Taverner^s con- 

 clusions. I have discussed the matter extensively with both of these 

 gentlemen, and have examined an immense amount of material in 

 various museums and private collections; but I must confess that 

 there are many perplexing problems yet to be worked out before the 

 relationships can be fully understood. 



Mr. Swarth (1926) says of the haunts of Harlan's hawk in the 

 Atlin region: 



These dark-colored Buteos were seen by us almost daily through the sum- 

 mer and in all parts of the region that we visited. On May 21 several were 



