402 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 



month I began to visit the nest as often as possible to ascertain as 

 nearly as I could when the chicks appeared and how long the hatch- 

 ing process lasted. It was not until March 6, at 2 p. m., that I found 

 one of the eggs pipped, a small round area no larger than a pea being 

 broken. On March 7 at the same hour the broken area was the size 

 of a dime. I could distinctly hear, however, several times repeated, 

 the low twittered note of the still imprisoned chick. The other eggs 

 still showed no sign. Bad weather and pressure of other work now 

 prevented a further visit until March 11 at 2.30 o'clock. Two very 

 callow owlets were now in the nest and one slightly pipped egg. The 

 young birds were not completely protected by their white down as 

 yet, the bare skin being visible between the tracts. On March 16 

 three young owls of different sizes were found in the nest, one being 

 quite markedly smaller than the other two. The query remains: 

 How long does it take a great horned owl's egg to hatch ? The above 

 are the data kept and anyone can make estimates on them. It 

 seems certain that these birds did not lay an egg oftener than once 

 in two days and that the period of incubation could not have been 

 less than 30 days, with the probabilities on the side of a rather longer 

 period. 



For our second year's work we had the experience of the first to 

 go on, we were more confident of the owlets' ability to bear exposure, 

 and so decided to photograph them at least once a week, let the 

 weather offer what it would. And the offerings were of sufficient 

 variety. On March 16, with the young 4, 6, and 8 days old, approxi- 

 mately, the temperature was well above freezing and comfortable, 

 but we were unable to expose a plate until 4 p. m., the sun became 

 covered with black clouds, and we were on the shady side of the tree. 

 We were not hopeful, but a long exposure accomplished our purpose. 

 In addition to the parts of three adult cottontails and one bobwhite, 

 which the camera shows, a fourth rabbit and a second bobwhite, also 

 a plump field mouse, do not appear in the picture, being tucked away 

 under the overhanging roof to the left or buried under other remains. 

 It was chilly on March 30 and a high wind was blowing in from the 

 northwest. On April 13 we had a regular northwest gale to contend 

 with and freezing temperature added. We varied our work with the 

 camera by runs across the frozen timber pasture. Why it was that 

 our negatives taken on these last two dates did not show motion we 

 have never satisfactorily explained to ourselves, for only time expo- 

 sures could be used. Certain it is that both the big elm and our 

 nearly 30-foot stretch of ladder were swaying back and forth under 

 the lash of that roaring wind. The gentle rain that was falling when, 

 on April 18, Mr. Benedict helped me bring the now lively owlets to 

 the base of the old nest tree, proved to be really no obstacle at all. 

 It splashed water against the lens of the camera but the negatives 



