The Horned Owls 



Nesting. — Nest: A cranny or inaccessible ledge of cliff, or a deserted nest of 

 Swainson Hawk, Western Redtail, Yellow-billed Magpie, or Western Crow; indifferently 

 lined, or not, with a few bark-strips, grass-tufts, and feathers. Rarely in hollow trees. 

 Eggs: 2 or 3, rarely 4; rounded ovate, white, lusterless, granular. Av. of 36 specimens 

 from San Luis Obispo County in the M. C. O. colls.: 53.3 x 43.9 (2.10 x 1.73); index 82. 

 Season: February-April; one brood. 



Range of Bubo virginianus. — The Americas, except Amazonia. 



Range of B. v. pacificus (chiefly contained within California). — California, 

 except the southeastern portion, the humid coastal strip (narrowly) north of Latitude 

 35, and (possibly) the extreme northeastern portion, north into south-central Oregon, 

 east to San Francisco Mountains, Arizona, south to northern Lower California. 



Authorities. — Gambel (Bubo virginianus), Proc. Acad. Nat. Sci. Phila., vol. iii., 

 1846, p. 46 (Calif.); Stone, Auk, vol. xiii., 1896, p. 156 (s. Calif.; diagnosis); Oberholser, 

 Proc. U. S. Nat. Mus., vol. xxvii., 1904, p. 183 (monogr.); Miller, Condor, vol. xii., 1910, 

 p. 13 (fossil) ; /. B. Dixon, Condor, vol. xvi., 1914, p. 47, figs, (life hist.; Escondido). 



No. 218b Desert Horned Owl 



A. O. U. No. 375a. Bubo virginianus pallescens Stone. 



Synonyms. — Western Horned Owl. Pallid Horned Owl. 



Description. — Adult: Similar to B. v. pacificus, but much paler, the ochraceous 

 tawny element largely replaced by white, sometimes nearly wanting below, the barring 

 of underparts usually narrower and finer. Adult male: wing 341 (13.43); tail 215.9 

 (8.50); bill from cere 27.3 (1.07). Adult female: wing 362.8 (14.28); tail 222 (8.74); 

 bill from cere 29 (1.14). 



Remarks. — This is a clearly marked bleached form, well established in the 

 arid Southwest. Although the range of B. v. pacificus is said to overlap that of palles- 

 cens (in the San Francisco Mts.), there is very little evidence of gradation within the 

 limits of California. 



Recognition Marks. — As in preceding form; much lighter. 



Range of B. v. pallescens. — The southwestern United States from central Texas 

 west to southeastern California and northwestern Lower California, south into northern 

 Mexico. 



Distribution in California. — Resident along the Colorado River, in the Im- 

 perial Valley, and in wooded portions of the Colorado and Mohave Deserts. To a 

 limited degree also in the desert ranges. 



Authorities. — Baird (Bubo virginianus), Rep. Pac. R. R. Surv., vol. ix., 1858, 

 p. 49, part (Colo. River, Calif.); Oberholser, Proc. U. S. Nat. Mus., vol. xxvii., 1904, 

 p. 182 (monogr.);/. Mailliard and J. Grinnell, Condor, vol. vii., 1905, p. 74 (Victorville; 

 food) ; Grinnell, Univ. Calif. Pub. Zool., vol. xii., 1914, p. 129 (Colo. Valley). 



No. 218c Western Horned Owl 



A. 0. U. No. 375a, part. Bubo virginianus occidentalis Stone. 



Description. — Adult: Similar to B. v. pallescens, but larger and averaging darker 

 in coloration. Adult male: wing 349.6 (13.76); tail 212.8 (8.38); bill from cere 27.1 

 (1.07). Female: wing 376 (14.80); tail 230.5 (9.07); bill 30.2 (1.19). 



Range of B. v. occidentalis. — Central western United States from Kansas and 

 Minnesota west to northwestern California and north to central Alberta. 



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