May, 1913 
SOME NOTES ON THE NESTING OF THE SHORT-EARED OWL 
123 
female at the nest with the young as long as they remained in the nest. After 
they left, both birds were generally on guard, and, when I searched for the 
young, the female also went through the performance of feigning wounded that 
1 have described above. 
On the next morning, June the nth, in order to get a basis for studying the 
development and relative ages of the young birds, I examined each one care- 
fully, recording points in the development of the plumage and making measure- 
ments as well as I could, of the total length, wing, and bill of each bird. I hoped 
later to supplement this by further observations, and get a fairly complete record 
of the growth and development ; but owing to the habit the young have, ot leav- 
ing the nest long before they are able to fly, my studies were not nearly so com- 
plete as I had wished them to be. I obtained the approximate ages of the young 
by estimating that of the youngest bird, and obtaining the differences in ages be- 
tween the others, by watching their development. The youngest bird I judged 
to be three days old. It may have been as much as four or five, or as little as 
two, but the chances are more in favor of three as correct than the other 
figures. I numbered the birds in my note-book from i to 9, beginning with the 
youngest, and I finally constructed the following table showing the comparative 
ages and measurements of each bird. These measurements cannot be considered 
to have the scientific exactness of figures taken by measuring bird sk- 
it is difficult to measure a living bird exactlv in the field. 
ins, because 
No. 
Age (days). 
Length (inches), 
Wiiig (inches). Bill 
(inches) . 
1. 
3 
3.35 
0.70 
0.25 
2. 
5 
4.50 
1.00 
0.30 
3. 
7 
5.50 
1.40 
0.37 
4. 
9 
6.50 
1.75 
4.42 
5. 
10 
6.80 
1.95 
0.50 
6. 
12 
7.25 
2.25 
0.48 
7. 
14 
7.50 
3.10 
0.56 
8. 
14 
7.70 
3.18 
0.54 
9. 
14 
7.75 
3.40 
0.52 
These figures show among other things, that incubation did not begin until 
the third egg was laid, and that eggs were laid irregularly after that, at periods 
of from one to two days. 
Aside from this table, I obtained but one other measurement to show the 
growth. This was on July i, when I found no. 6 at a considerable distance from 
the nest, when approximately 31 days old. I had nothing to measure the bird 
with then, but determined that its wing measured about 8^2 inches, hy comparing 
its length with that of my hand, and measuring my hand later. With these meas- 
urements I attempted to construct curves to show the growth graphically, but 
found the data hardly sufficient to make these of much value. However they 
did show that the period of fastest growth was between the approximate ages of 
four and eight days. 
My observations on the development of the plumage were as follows. On 
June II, when the birds were measured, no. i was downy all over, with no sign 
of feathers. The eyes were closed. The down was of a light cream color. No. 
2 had sheathed feathers appearing on the shoulders, wings, back of neck and 
breast, but nowhere else. The feathers were all tightly sheathed, and the eyes 
were still closed. No. 3 had feathers coming through on the back, legs and facial 
disc, while the feathers of the shoulders, wings, back of neck and breast were 
just beginning to break the sheaths at the tips. The eyes were beginning to open 
a little. No. 4 had feathers coming through everywhere, and the sheaths break- 
ing on all of them except the wing and tail quills, and the feathers of the facial 
disc. The eyes were farther opened, but only appeared dull blue through the 
