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); J. 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, LTniv. Calif. Pub. Zool., vol. xii., 1914, p. 129 (Colo. Valley). 
No. 218c Western Horned Owl 
A. O. U. No. 375a, part. Bubo virginianus occidentalis Stone. 
Description.- — Adult: Similar toB. 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. 
