HISTORY OF CERTAIN GREAT HORNED OWLS—KEYES. 401 
one’s cap, and quickly duck one’s head as the great missile rushes 
past. The owl keeps straight on her course and alights with heavy 
impact on a branch of a neighboring tree. Here she faces about and 
very likely comes straight back again. This process became finally 
a bit too exciting and, after making certain that the headless quad- 
ruped lying in the nest over behind the owlets was just a big house 
rat, I slipped down the ladder and went home. 
February 7, 1907, was cold and clear after the terrific snowstorm 
of the night before. On this day Mr. James R. Smith, a young farmer 
of the vicinity who had always been interested in birds and who was 
destined to be my skillful assistant throughout the season, accom- 
panied me to the snow-covered timber pasture. As we approached 
the nest tree of the year before a fox squirrel leaped from one of the 
smaller adjacent trees and, starting up the big elm, ran along the 
rim of the great knothole which formed the owls’ doorway, and 
scampered onto a topmost branch. If the owl were at home the 
saucy fellow surely passed within 10 inches of herface. For a moment 
we felt dubious as to the nest being occupied. As we approached the 
tree, however, a great horned owl flew from one of the higher branches, 
aroused either by the squirrel or, more likely, by our own approach. 
This was more favorable. We gave the tree a few kicks, when the 
sitting bird hopped up lightly to the rim of the cavity, looked across 
the white landscape for several seconds, then spread her nearly 5 
feet of wings and flew silently away. 
Our first mistake for 1907 was in not looking into the nest on 
this first day. Our reasons for not doing so were the belief that the 
set of eggs could hardly be complete at this time and especially the 
fear that the egg or eggs could not stand exposure even for a short 
time on so cold a day. My present belief is that this fear was 
unfounded. Just two days later, on February 9, at about 3 o’clock 
in the afternoon, I visited the nest again and found the set of three 
eggs complete. These were lying in a slight hollow as before, but as 
far back in the cavity as possible. Except for a small space about 
the eggs the house was filled, even to the doorsill, with snow. It 
was a picture, indeed, but one over which we did not dare tarry in 
freezing weather. All the eggs were nest stained and it did not look 
as if any one of them had been laid that day. However, this was 
uncertain, and I had lost a possible opportunity of learning just when 
the set became complete. This was regrettable, for no one seems to 
know the period of incubation of an egg of the great horned owl. 
The older ornithologists made their guess at 3 weeks. Bendire later 
expresses his belief that this period is too short and that 4 weeks is 
probably nearer to the truth. I have not determined the point, 
though my data still possesses some interest. Toward the end of the 
38734°—sm 1911——26 
