98 IOWA ACADEMY OF SCIENCES. 



the egg; the sixth egg showing the lilac shell markings 

 noticed in only a few of the eggs. 



A second set was laid and three young were hatched, 

 but were killed before reaching maturity. Shortly after 

 this one of the old birds was shot. The remaining falcon 

 staid until June, when it disappeared, and none of this 

 species have since been seen in the vicinity of the Palisades. 



In considering this series of observations carried on 

 through seven consecutive years, one cannot help being 

 impressed with the tenacity with which these birds cling 

 to their favorite nesting locality. The variation in the 

 eggs of this species, and especially this pair of birds, is 

 noteworthy. From almost unmarked specimens one may 

 find gradual variation to eggs which show almost no trace 

 of the ground color and whose spots are in places almost 

 black. Some show sharp contrasts, wdiile others lack it 

 entirely. This series of sets consists of thirty-three eggs 

 and contains two sets of six, one of five and four sets of 

 four eggs each. Probably nowhere in the United States is 

 there a more complete and interesting series of sets of this 

 particular species. 



The longest egg measures 2-3.96 inches, while the short- 

 est is 1-78.96, a difference of 21.96 inches. In breadth the 

 variation is almost as great, the broadest being 1-66.96, the 

 narrowest 1-47.96, a difference of 19.96 inches. The varia- 

 tion in number is also great, three being the smallest com- 

 plete set and six the largest. 



In no case where a second set was laid did the number 

 exceed three. Unfortunately no measurement of the 

 second set laid were secured, and this prevents us from 

 knowing whether these eggs were smaller in size as well 

 as fewer in number than the first sets. 



The food, so far as observed, consisted entirely of birds, 

 and at least four different species are known to have been 

 ta.ken. The increasing popularity of the Palisades as a, 

 summer resort, together with the presence of a lai'ge stone 

 crusher located near the cliff where these noble birds once 

 nested, precludes the likelihood of their return to this- 

 once favored locality. 



