208 Birds of Colorado 
Habits—The Flammulated Screech Owl resembles 
the other larger Screech Owl in its habits. It is nocturnal, 
and preys on small mammals and large insects. The 
eggs are laid in a natural cavity or in a Filicker-hole, 
generally in a coniferous tree—a pifion at lower levels, 
a spruce at higher—at the end of May or beginning 
of June. 
Aiken was the first to find the nest and eggs of this 
Owl. He took a female from the nest, which was in 
a dead pine tree and contained one egg. This was in 
the Wet Mountain Valley, at about 7,500 feet, on June 
15th, 1875. W. G. Smith subsequently obtained several 
sets of eggs in Estes Park, between 8,000 and 10,000 
feet. The clutch usually numbers four, and the eggs 
are white with a faint creamy tinge, and oval in shape; 
they average 1°12 x 10. 
Genus BUBO. 
Large Owls with wing (in the American species) over 14 ; bill robust 
and black ; facial disk well marked, the eyes placed nearer the upper 
than the lower margin ; skull and ear-openings symmetrical, the latter 
small, normal and non-operculate ; ear-tufts conspicuous ; wing rather 
short and rounded, falling short of the tail when folded ; tail slight, 
rounded, almost concealed below by the lengthened under tail- 
coverts; legs densely feathered to the bases of the claws, but the 
latter not concealed. 
A considerable genus, spread over most of the world; but with only 
one United States species, divided into a number of subspecies ; some 
of these however are far from satisfactorily defined, 
Western Horned Owl. Bubo virginianus pallescens. 
A.O.U. Checklist no 375a—Colorado Records—Ridgway 73, p. 185 ; 
Henshaw 75, p. 407; Scott 79, p. 95; Beckham 85, p. 143; Drew 85, 
p- 17; Morrison 88, p. 115; 89, p. 67; Kellogg 90, p. 87; Bendire 92, 
p. 383; Osburn 93, p. 212; Lowe 94, p. 268; 95,p.169; Dille 03, 
p. 74; Henderson 03, p. 235 ; 09, p. 230; Oberholser 04, p. 192 (Asio 
magellanicus occidentalis); Warren 06, p. 20; 08, p. 21; 09, p. 14; 
Gilman 07, p. 154; Rockwell 08, p. 14; 08, p. 163; Smith 10, p. 133. 
