The Siberian Rough-Legged Hawk in Alaska
The Siberian Rough-legged Hawk in Alaska
The last edition of Lhe A. 0. U. Check-list gives only one form of the Rough-legged Hawk, Buteo lagopus s.johannis, as occurring in North America. However, while studying this species in connection with my work on the continuation of Ridgway's unfinished “Birds of North and Middle America,” I found that the Siberian race pallidus has been collected at St. Michaels, Alaska. A male shot there by E. W. Nelson on September 16, 1879, is so much closer to Asiatic birds (pallidus) than to the American subspecies that I consider it to he pallidus a female without definite locality other than “West Coast, Alaska,” taken by J. W. Johnson, April 10, 1886, is intermediate in color between s.johannis and pallidus, but is large like the latter form; a male taken at St. Michaels by L. M. Turner, April 10, 1876, agrees in color with s.johannis but in size with pallidus. The race pallidus is larger than s.johannis and has the pale margins, of the feathers of the upperparts lighter and broader than in the latter, especially in the young birds. The three Alaskan specimens mentioned above have wing lengths of 430, 434 mm. (males) and 447 mm. (female), as against 397-415 (average 407 mm.) in the males, and 395-438 (411 mm.) in the females of s.johannis.
A male from Kowak River, Alaska, kindly loaned me by Dr. Grinnell from the collection of the Museum of Vertebrate Zoology (no. 32253) is small like s.johannis (wing 392 mm.) but is unusually pale for that form, suggesting an approach to pallidus in color. It is interesting to note in this connection that a specimen in the U. S. National Museum from Bering Island is large like pallidus, but is dark for its race, approaching s.johannis. These two, the St. Michaels bird collected by Turner, and the specimen taken by Johnson, suggest that in a region where the two races merge (as in the Bering Sea area) the size character remains more fixed than the coloration and is therefore a more reliable criterion. The single specimen recorded from the Pribilof Islands is of the American form s.johannis, which is the race found throughout the Aleutian lslands as I well.
Herbert Friedman
U. S. National Museum, August 18, 1934
