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 May, 1913 SOME NOTES ON THE NESTING O1' 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 feig-ning wouncted that I have described above. On the next morning, June the th, 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 eich 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, oI 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  to 9, beginning with the youngest, and I finally constructed the following table showing the cornparauve ages and measurements of each bird. These measurements cannot be considered to have the scientific exactness of figures taken by measuring bird skins, because it is difficult to measure a living' bird exactly in the field. No. Age (days), Length (inches), Wing (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 , when I found no. 6 at a considerable distance from the nest, when approximately 3 days old. I had nothing to measure the bird with then, but determined that its wing measured about 8 inches, by 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 , when the birds were measured, no.  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 .&11 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