MONTANA HORNED OWL 35 \ 



were in a depression over two inches deep hollowed out of the sand 

 on the ledge." 



Eggs. — This subspecies usually has two and often three but rarely 

 four, white eggs. The measurements of six eggs average 54.8 by 46.3 

 millimeters; the eggs showing the four extremes measure 56.5 by 48.2, 

 53 by 45.5, and 54.6 by 45.3 millimeters. 



Strange to say, the earliness, or tardiness, of the season seems to 

 have little to do with the actual laying of the eggs. My experience 

 has been that the period of incubation is 28 days, usually performed by 

 the female, although the male sometimes takes her place temporarily. 

 But Cameron (1907) says the male sits alternately with her, and 

 shares the duties of incubation. On the other hand, Sclater (1912) says 

 that incubation is "undertaken entirely by the female." Sometimes, 

 while the female is on the nest, the male will be close by and may even 

 be found crouching on the nest beside his mate (Treganza, 1914). 

 While their eggs are still unhatched, the adults do not ordinarily resent 

 intruders. Rockwell (1908), of Colorado, writes: "A week later 

 [March 17] we returned. * * * The owl evidently heard us and as 

 she raised up we could plainly see her head above the rim of the nest. 

 We promptly got our cameras into action and after making a couple 

 of exposures from the ground, climbed a tree about 25 feet from the 

 nest. * * * This did not seem to frighten her, but when we got half 

 way up a tree within 15 feet of the nest the old bird flopped off the 

 nest and out of sight. An examination of the nest revealed two eggs 

 in which incubation had begun. The nest contained many more 

 feathers than on the previous week." 



Donahue (1923) says of a Kansas pair: "Clyde was almost up to the 

 nest before the old owl flew off. * * * The male soon came sliding 

 through the woods from up the draw, and joined its mate in protesta- 

 tions in the form of beak clickings and deep 'Whooo-hoooos' from trees 

 around about." 



Wolfe (1912) says that he took two sets of eggs, one of four on 

 March 24, 1910, and just one month later two eggs that were not 

 quite so large. And I think I am correct in writing that it is usual for 

 the second set of eggs to be both fewer in number and somewhat 

 smaller in size. Sclater (1912) says that: "Gale found it a most per- 

 sistent layer; he took three sets of eggs from the same pair of birds; 

 the sets numbered four, three and two respectively, and the nest-site 

 was changed each time." 



Young. — With the arrival of their young, the parents become fiercer, 

 and may later boldy attack any person approaching the nest. Cook 

 (1926) says that he found a nest tree, "an easy one to climb and I 

 was making fairly good progress toward the nest and had gotten 

 within about six feet of it, when the unexpected happened. Mrs. Owl 

 who had perched on a tree nearby to watch the proceedings, suddenly 



