330 BULLETIN 17 0, UNITED STATES NATIONAL MUSEUM 



I once found a nest containing five." The eggs are just like those of 

 other horned owls. The measurement of 50 eggs average 55 by 45.9 

 millimeters ; the eggs showing the four extremes measure 58.9 by 50.8, 

 50.1 by 45, and 52.6 by 41.2 millimeters. 



Food. — Mr. Henderson (1925) says: "Their principal food in this 

 section is the varying hare and they are much more plentiful at the 

 periodical times of abundance of these animals." Mr. Farley tells 

 me that "remains of Hungarian partridges have been found in pellets 

 picked up near their nests." Mr. Preble (1908) writes: "One taken 

 November 21 had eaten a small shrew (Sorex personatus); one Novem- 

 ber 23, a red squirrel (Sciurus hudsonicus); one December 1, several 

 meadow voles (Microtus drummondi) , white-footed mice (Peromyscus 

 arcticus), shrews (Sorex personatus)." He also mentions three that 

 had eaten several large water beetles (Dytiscus dauricus). 



This owl seems to be almost wholly beneficial in the regions that it 

 lives. 



Its plumage changes, behavior, and voice do not seem to differ 

 materially from those of other horned owls. It is more migratory 

 than the other races, as it is difficult for it to find sufficient food in its 

 far northern home in winter. In the big flights of northern owls that 

 drift into New England and other northern States during certain 

 winters, specimens of very pale birds are occasionally found that are 

 referable to this subspecies. Mr. Farley says in his notes: "The 

 Arctic horned owl is a fairly regular winter visitor to central Alberta. 

 In lesser numbers it is a resident throughout the year. The migrants 

 from the north and west make their appearance in September and 

 October and remain until February." 



BUBO VIRGINIANUS SATURATUS Ridgway 

 DUSKY HORNED OWL 



HABITS 



Contributed by Milton Philo Skinner 



This subspecies, living as it does in the dark, humid coast forests 

 of northern California, Oregon, Washington, British Columbia, and 

 Alaska, is the darkest of the horned owls. But its habits and ways 

 of life closely resemble those of other western forms. 



Nesting. — In California these owls are apt to have their homes in the 

 tops of oaks, in canyons, as a rule 30 to 50 feet above ground. Some- 

 times they nest in firs, and the nests are usually made of coarse sticks. 

 Whether this subspecies ever builds its own nest is not known; but it 

 is known to adopt old hawk nests, just as members of other sub- 

 species do. 



Eggs. — [Author's note: The eggs of the dusky horned owl are 

 like those of the other horned owls of similar size. Apparently, from 





