370 LIFE HISTORIES OP NORTH AMERICAN BIRDS. 



The number of eggs laid is usually three or four, rarely five. They are 

 similar in shape and color to those of the rest of this genus. Now and then a 

 set is found which is so badly stained by the excrement of fleas inhabiting 

 their burrows in large numbers that the eggs, judging by their color, might be 

 taken for those of the Sparrow Hawk. 



The average measurement of twenty specimens is 34 by 29.5 millimetres. 

 The largest egg of this series measures 36 by 31, the smallest 32.5 by 27.5 

 millimetres. 



The type specimen, No. 20569 (PL 12, Fig. 11), U. S. National Museum 

 collection, selected from a set of four from the Bendire collection, was taken by 

 the writer near Tucson, Arizona, on March 26, 1872. 



128. Megascops asio aikeni Bkewstee. 



aiken's screech owl. 



Megascops asio aikeni Brewster, Auk, vm, April, 1891, 139. 



(B — — R — C — , U 373gr.) 



Geographical range : Southern Colorado (south probably to central New 

 Mexico and northeastern Arizona). 



According to Mr. William Brewster, who recently described this new race, 

 Aiken's Screech Owl is of about the same size as the California Screech Owl, 

 and resembles Megascops asio trichopsis somewhat in coloration, but with the 

 mesial streaks and stripes of dull black coarser and more conspicuous, thus 

 giving it a darker appearance. 



The type was obtained by Mr. Charles E. Aiken in El Paso County, Colo- 

 rado, on May 29, 1872, and according to his observations it is not uncommon 

 among the cottonwood timber along the creeks in El Paso and Fremont Coun- 

 ties, in central Colorado. It inhabits similar localities as the Rocky Mountain 

 Screech Owl, and the latter is frequently found, in the winter at least, in the 

 same groves with this subspecies, whose range it overlaps here. 



It is questionable if Aiken's Screech Owl occurs at any points north of 

 Douglas County, Colorado, but it probably inhabits all the more open country 

 along the foothills of the southern Rocky Mountains south at least to central 

 New Mexico and northeastern Arizona. 



Dr. R. W. Shufeldt, U. S. Army, found a Screech Owl breeding near Fort 

 Wingate, New Mexico, which I think is referable to this subspecies. He took 

 three well incubated eggs on April 18, 1887, from a cavity in an oak tree 10 

 feet from the ground, capturing alive both parents at the same time. I have 

 seen photographs of these specimens, and they show every indication that the 

 originals belonged to this race. The eggs are now in the U. S. National Museum 

 collection, and resemble those of the other members of this genus in shape and 

 color, and average slightly larger than the eggs of the Mexican Screech Owl, 

 measuring 36.5 by 31, 36 by 30.5, and 34.5 by 31 millimetres. A pair of 



