252 PROCEEDINGS OF THE NATIOyAL MUSEUM. vol.49. 



of Dr. Joseph Grinnell I have been able to examine the type of Strix 

 occidentalis liuacTiucae; and Dr. Louis B. Bishop has obUgingly sent 

 two specimens from New Mexico, together with three from Arizona, 

 and two of Strix occidentalis occidentalis from CaUfornia. Through 

 Mr. H. S. Swarth it has been made possible to borrow nine more 

 specimens of Strix occidentalis occidentalis from CaUfornia, which he 

 had brought together for a further study of his Strix occidentalis 

 Jiuachucae. He, furthermore, very courteously offered the writer the 

 use of his manuscript notes made with the view of pubUshing a sup- 

 plementary account. The above material, altogether 31 specimens, 

 including 2 in juvenal plumage, constitutes by considerable the 

 largest series of birds of this specks that has ever been available at 

 one time. A careful study of these for the purpose of identifying 

 specimens in the collection of the Biological Surve}^, compels some 

 surprising as well as interesting conclusions, which seem worthy of 

 printed record. 



The eight adult examples from New Mexico, together with the six 

 from southern Arizona, represent what should be typical Strix occi- 

 dentalis Tiuachucae. This race, quoting the original description,^ 

 differs from Strix occidentalis occidentalis as follows: 



"Similar to Strix occidentalis occidentalis (Xantus), but sUghtly 

 smaller, and conspicuously paler; white markings more extensive 

 and dark areas less deep toned," 



An exhaustive comparison of this series of 14 adults from New 

 Mexico and Arizona with typical Strix occidentalis occidentalis shows 

 that all but one of the characters given to separate Strix occidentalis 

 Tiuachucae are merely individual. The difference of size is inconsider- 

 able and inconsequential, as the appended measurements demonstrate; 

 while the supposedly most important distinction, that of the lighter 

 tone of the dark areas, appears in but five of the fourteen specimens, 

 and many of the others are even darker than normal Strix occidentalis 

 occidentalis! A single bird from Tucson, Arizona (No. 84433, U.S.N.M) , 

 is the palest of the present series, being, in its light rufescent brown 

 coloration, very much like the type of Strix occidentalis huachucae, but 

 even lighter and more rufescent, with more tinge of ochraceous on the 

 face and lower parts. A specimen from the Santa Rita Mountains (No. 

 241139, U.S.N.M.), some 30 or 40 miles south of Tucson is, however, as 

 dark as the type of Strix occidentalis caurina, the supposedly darkest 

 form of the species. Other examples from New Mexico are even darker. 

 Thus, light rufescent birds like the Tucson specimen above mentioned, 

 together with others nearly as light in ground color, from New Mexico 

 and Arizona, are found geographically intermingled with dark birds, 

 and must be considered, therefore, merely as representing a color 

 phase. There is, likewise, nothing but individual variation in the 



> Swarth, Univ. Calif. Publ. Zool., vol. 7, No. 1, May 26, 1910, p. 3. 



