96 IOWA ACADEMY OF SCIENCES. 



1-89.96 inches, and in breadth from 1-59.96 inches to 1 -68.96 

 inches. Oneeg^ was very heavily colored, one very lightly 

 spotted and one was marked most heavily at the small end. 

 The eggs were fresh, four in number, and were placed in a 

 hole which extended four feet into the face of the cliff and 

 was sixty feet above the water. This seemed to be their 

 favorite cestingplace, although, when persistently molested 

 they would desert it for two other places, as will later be 

 noted. 



In no case was there to be found any nesting material 

 carried by the birds to the nesting site. Occasionally the 

 feather of a Flicker (Colaptes auratus) or Kingfisher (Ceryle 

 alcyon) would be found, but the eggs were always laid on 

 the powdered rock or pebbles in the back part of the hole. 



In the same year, (1893), on May 2d, I collected a sec- 

 ond set of three eggs in the same cliff, but placed in a niche 

 about thirty feet above the water, and accessible by climb- 

 ing from a boat below. This nesting site was used two 

 years later by a pair of (}t. Horned Owls. 



In 1894 the Duck Hawks nested in their favorite place 

 and continued to nest there till 1897. The first set in 1894 

 contained four fresh eggs, April 12th, which varied in 

 length from 1-89.96 to two inches, in breadth from 1-59.96 

 to 1-61.96. In this set one e^g was very heavily marked, 

 and in one the blotches were confluent about the smaller 

 end. The other two are not peculiar. 



A second set of three eggs was allowed to hatch. The 

 birds laid almost immediately after the first set was taken 

 and the young were about near the last of May or first of 

 June. 



On April 12, 1895, a set of five eggs was collected, which 

 vary in color only with regard to the amount of light back- 

 ground showing through the deep reddish brown spots and 

 washes. In size they vary from 1-86.96 to two in length 

 by 1-58.96 to 1-66.96 in breadth. 



About two weeks later a second set of three was taken, 

 one of which was almost without markings, another very 

 heavily marked with red, while the third was scarcely 



