284 BULLETIN 17 0, UNITED STATES NATIONAL MUSEUM 



the eggs showing the four extremes measure 35.5 by 29, 35 by 30, and 

 32.5 by 27.5 millimeters. 



Food. — Mr. Brown (Bendire, 1892) says: "Small birds, kangaroo 

 rats, gophers, different species of mice, lizards, scorpions, grasshoppers, 

 and beetles are their staple articles of diet." 



Mrs. Florence M. Bailey (1923) found one in a cottonwood stub on 

 the bank of the Santa Cruz River and says: "The pellets taken from 

 the cavity contained bones of wood rat, kangaroo rats, pocket mice, 

 deer mice, and a grasshopper mouse, the skull of one young Neotoma 

 albigula, numerous jaws and bones of Perodipus ordii and Dipodomys 

 merriami, together with a few jaws of Perognathus eremicus, Peromys- 

 cus eremicus and sonoriensis, and Onychomys torridus." 



Voice. — Dr. Loye Miller (1928) says of some that he heard 

 repeatedly: 



When whistling they invariably occupied a perch less than five feet from the 

 ground, in dense willow tangle grown up from beaver cuttings to a height of twenty 

 feet or more. Out of the midst of this brush, birds were repeatedly called (or 

 stimulated or what you will) by imitating the whistled note. They came out 

 into the moonlight and circled my body so closely that the faint bat-like flutter 

 of the wings was plainly audible and one bird perched within two feet of me, where 

 it was clearly visible in the moonlight. Otherwise they always returned to the 

 depth of the thicket where the two birds collected were searched out with the elec- 

 tric flash light. 



The song (?) of all individuals was the same in its composition, though the abso- 

 lute pitch might differ by a major third. The composition of the performance 

 differed from the customary note of the race of the San Diegan district (Otus 

 asio quercinus Grinnell) in being made up of two tetrads of notes of equal tempo but 

 with the first one pitched a half tone above the second. The final note of the 

 second tetrad slides down to a slightly flatted pitch. I heard no other whistle 

 from the Colorado River birds. 



OTUS ASIO XANTUSI (Brewster) 

 XANTUS'S SCREECH OWL 



HABITS 



This small, pale screech owl is known only from the southern part 

 of the peninsula of Lower California, Mexico. Dr. Joseph Grinnell 

 (1928b) says: "Common resident in the Cape district, whence re- 

 ported from many localities, all south of La Paz. Apparently occurs 

 from the coastal lowlands (Arid Tropical life-zone) up to the tops of 

 the Victoria Mountains." 



William Brewster (1902) in naming it, describes it as "most nearyl 

 like M(egascops) vinaceus Brewster, but smaller, the general coloring 

 paler and less reddish, the crown and outer surfaces of the wings lighter, 

 the primaries with broad, well-defined light bars on both webs, the 

 abdomen and flanks decidedly whiter, the under tail coverts nearly 

 pure white and practically without mesial streaks, the feathering of 

 the legs shorter and sparser." 



