NESTS OF THE DUCK HAWK 



159 



The writer is inclined to believe that despite their infrequent oc- 

 currence in any one locality there are more of these Falcons an- 

 nually within our borders than is commonly believed. 



The Duck Hawk nests either in a natural crevice in a cliff, or in a 

 cavity in some tall tree. The almost vertical limestone cliffs common 

 along the rivers in many parts of eastern Iowa, as well as hollows in 

 tall trees, afford suitable nesting sites. Often the only means of ac- 

 cess, where the nest is placed on a cliff, is by means of a rope lowered 

 from above. The eggs are laid directly upon the rocks or the bottom 

 of the nesting cavity, there being no attempt at nest building. 



From three to six eggs form a complete set, and are deposited us- 

 ually during the first half of April. If the eggs of the first setting are 

 taken, another clutch will be laid, the birds being strongly attached to 

 a nesting site once it has been chosen. Second sets have usually a 

 smaller number of eggs, and they are likely to be less heavily marked 

 than those of the first clutch. 



In color, the eggs vary from buff or dirty white and almost un- 

 marked to those so heavily marked with reddish-brown as to nearly 

 conceal the ground color. Mr. Burge has in all a series of seven 

 beautiful sets, two of them of six eggs each, one of five, and four of 

 four eggs each. An average egg measures about 2 by 1.55 inches. 



Fig. 64. Map showing distribution in Iowa of the Duck Hawk. 



