386 LIFE HISTORIES OF NORTH AMERICAN BIRDS. 



birds not yet able to fly are occasionally found so late in the season, and some- 

 times in localities where they certainly had not been disturbed previously, it 

 would appear as if a second might now and then be reared. A few days after 

 my arrival at Fort Klamath, Oregon (June 18, 1882), one of my men brought 

 me a young Owl of this subspecies which he had caught alive in the pine 

 forest south of the post. It could barely fly at the time, and if not from a 

 second brood the eggs must have been laid several weeks later than usual. 



The eggs number two or three to a set, occasionally four, and sets of 

 three are about as often found as the smaller number, while those of four 

 are not especially rare. Mr. Charles F. Morrison reports taking one of six 

 in Wyoming, an extremely large set, and Mr. Charles C. Neale writes me 

 that he took a set of five eggs from a nest in an oak tree in the mountains 

 in Plumas County, California. 



They are deposited generally at intervals of two or three days, the 

 female attending to the duty of incubation exclusively, I believe, and which 

 lasts about four weeks. The male supplies his mate with the necessary food 

 while she is so engaged, and when not hunting is usually found in close 

 proximity to the nest. The eggs are similar to those of the Great Horned 

 Owl. 



The average measurement of fifteen specimens in the U. S. National 

 Museum collection is 55.5 by 47 millimetres. The largest egg of this series 

 measures 58.5 by 48.5, the smallest 53.5 by 45 millimetres. None are figured. 



135. Bubo virginianus arcticus (Swainson). 



ARCTIC HORNED OWL. 



Strix (Bubo) arctica Swainson, Fauna Boreali Americana, 11, 1831, 86, PI. 30. 

 Bubo virginianus var. arcticus Cassin, Illustrated Birds of California, etc., 1854, 178. 

 (B 48, part ; 317a, part ; R 4056, C 463, part ; IT 3756.) 



Geographical range : Arctic America, chiefly the interior ; south, in winter to 

 the Great Plains (the two Dakotas, Montana, etc.). 



The breeding range of the Arctic Horned Owl, a much lighter colored 

 race than the two preceding forms, is confined, as far as known at present, 

 to those parts of the interior of British North America situated between James 

 Bay (Moose Factory), the west shores of Hudson Bay, and the eastern slopes 

 of the Rocky Mountains, north of latitude 51°, and extending in a northwest- 

 erly direction to northern Alaska, where a specimen was obtained by Mr. C. L. 

 Mackay on the Attoknagik River, August 24, 1881. Like the Western Horned 

 Owl it inhabits the more open country throughout its range, more especially 

 along the shores of the numerous lakes and streams found in those inhospi- 

 table regions. In winter it migrates southward, though rarely entering our 

 borders. As yet I have not seen a specimen of this race obtained within the 

 limits of the United States that could be called typical. While stationed at 



