204 Birds of Colorado 
Genus OTUS. 
Small Owls with wings under 7-5; facial disk not well developed, 
hardly noticeable; ear-tufts well developed; skull and ear-openings 
symmetrical, the latter small and normal; wing rounded, but long and 
about twice the short, rounded tail; tarsus feathered, toes bristly or 
naked ; plumage with marked dichromatic phases. 
A large cosmopolitan genus with only two North American species, 
but separated into a great many subspecies difficult to discriminate. 
A. Larger; wing over 6; toes bristly or partly feathered. 
a. Paler and less heavily streaked. QO. a. maxwelliz, p. 204. 
b. Darker and more heavily streaked. _ 0. a. aikeni, p. 205: 
B. Smaller; wing under 6; toes naked. O. flammeola, p. 207: 
Rocky Mountain Screech Owl. Otus asio mazwellie. 
A.O.U. Checklist no 373e—Colorado Records—Ridgway 77, pp. 210, 
213 ; 79, pp. 232, 235; Morrison 89, p. 66 ; Kellogg 90, p. 90; Bendire 
90, p. 298; 91, p. 91; 92, p. 263; Hasbrouck 93, p. 256; Cooke 97, 
pp. 78, 160; Burnett 03, p. 156 ; Dille 03, p. 74; Henderson 03, p. 235; 
09, p. 230; Rockwell 07, p. 140; 08, p. 207; H. G. Smith 08, p. 185. 
Description.—Very closely resembling O. a. aikeni, but very distinctly 
paler, the ground-colour much lighter, and the black streaking much 
less heavy, both above and below; white on the wings and scapulars 
more conspicuous, and a tawny wash across the back, showing rather 
plainly. Measurements average a little larger; wing 7-0, tail 3-5 (see 
Plate 5). 
Distribution.—North-east Colorado, chiefly north of the Arkansas 
Platte Divide, but occasionally in winter south to Colorado Springs ; 
extending northwards along the foothills as far as Fort Custer in south 
Montana. 
This Owl is a resident in north-east Colorado, and is found chiefly 
along the foothills and river valleys from Denver northwards. Kellogg 
reports it as rare in Estes Park, and it has been taken out on the plains 
as far as Dry Willow Creek in Yuma co., in June by H. G. Smith. 
Habits.—This Owl is an inhabitant of the cotton-wood 
groves along the Platte and its tributaries in north-east 
Colorado. It is chiefly abroad at night, spending the 
day in a hollow tree, or sitting quietly on a horizontal 
branch close to the trunk, which it closely resembles. Its 
home is generally betrayed by disgorged pellets lying below. 
The nest and eggs were first taken by Anthony on 
the Platte River, six miles from Denver, May 4th, 1884 ; 
