368 LIFE HISTORIES OF NORTH AMERICAN BIRDS. 



The average measurement of nine of these eggs in the U. S. National 

 Museum collection, all but one presented by Mr. Gale, is 36 by 29. .5 millime- 

 tres, the largest egg measuring 40 by 29.5, the smallest 34 by 29.5 millimetres. 

 Thirty-eight eggs taken by Mr. Gale average 36.5 by 30 millimetres. 



The type specimen, a single egg, taken on the Platte River near Denver, 

 Colorado, on May 4, 1884, by Mr. A. W. Anthony, No. 22450, is figured on 

 PI. 12, Fig. 10. 



127. Megascops asio trichopsis (Wagler). 



MEXICAN SCREECH OWL. 



Scops trichopsis Wagler, Isis, 1833, 276. 



Megascops asio trichopsis Ridgway, Proceedings U. S. National Museum, viii, 1885, 



355. 



(B — , C — R 403, C 470, U 373/.) 



Geographical range : Northwestern Mexico and the contiguous border of the 

 United States, in Arizona and New Mexico (Lower California?). 



The Mexican Screech Owl is a slightly smaller race of the common form, 

 and distinguished from it by its pure ashy gray plumage, with the middle 

 streaks black and in strong contrast; it is only found in this phase. Its range, 

 as far as known, extends from central Arizona and New Mexico south to north- 

 western Mexico, and probably Lower California, where a Screech Owl is known 

 to occur, but of which no adult birds have as yet been taken. A pair of 

 Screech Owls obtained by Mr. Vernon Bailey near Oracle, Pinal County, 

 Arizona, on June 11, 1889, are, according to Mr. William Brewster, interme- 

 diate between this race and the newly described Megascops asio aikeni, from 

 southern Colorado. 



Its hal)its are similar to the other members of this extensive genus, and, like 

 them, it nests in hollow trees or sahuaras (the giant cactus) in" abandoned ex- 

 cavations of the larger Woodpeckers, or in natural cavities, generally at no 

 great distance from the ground. 



I first met with this little Screech Owl among the shrubbery in the Rillitto 

 Creek bottom, near Tucson, Arizona, in 1872; it appeared to be rather rare 

 here and I saw but few. During February and March their weird, mournful 

 notes were frequently heard shortly after sundown. On March 10, I finally 

 obtained one, which was sitting in a bushy willow overrun with wild grape 

 vines. It was perched on a small limb close to the main trunk and did not 

 appear to have se^n me before I noticed it sitting in a drowsy attitude,- and 

 as soon as it saw me it straightened up, sat very erect, with all its feathers 

 pressed close to the body, making it appear nearly as long again, and it might 

 then have been easily mistaken for a slender stump of the limb on which 

 it was resting. I have no doubt but that it was done for the purpose of 

 mimicry and in which it is frequently successful. 



