COOPER'S HAWK 115 



While at the nest their actions were quick, nervous; and they placed the 

 sticks in several places before satisfied, but they did not remain at the uest 

 more than half a minute. 



If a set of eggs is taken from a nest the hawk will lay a second 

 set, about ten days or two weeks later, sometimes in the same nest, 

 but oftener in another nest hastily repaired. C. J. Pennock tells me 

 that, after taking four eggs from a nest on April 26, he took two 

 more eggs on May 5 and two additional eggs on May 11, all from the 

 same nest. 



If either one of a pair is shot during the nesting season, the 

 survivor usually secures a new mate quite promptly. J. Eugene 

 Law (1919) mentions the following incident, related by Maj. Allan 

 Brooks: "A female Cooper Hawk had been shot from her nest of 

 eggs. Some days later another female, in adult plumage, was found 

 incubating the same eggs, and was likewise shot. ^Yha.t w^as his sur- 

 prise later to find a third female occupying the nest, this time a bird 

 in the streaked plumage of a sub-adult. And as a matter of curiosity 

 she was allowed to, and did, raise the brood." 



Eggs. — Four or five eggs form the usual set for Cooper's hawk; 

 sometimes only three are laid ; I have taken one set of six and heard 

 of two or three others. Just half of the sets recorded in my notes 

 have been of four, and one-quarter of them of five. They are de- 

 posited at intervals of one or two days. The eggs are rounded-ovate 

 to ovate in shape, and the shell is smooth but not glossy. The color, 

 when fresh, is bluish w^iite or greenish white, which fades out to 

 dirty white. They are generally nest stained but otherwise im- 

 maculate and not attractive in appearance. From 25 to 50 percent 

 of the eggs show more or less scattered spotting in pale browns or 

 buffs; rarely some of them are as heavily marked as some of the 

 paler types of red-shouldered hawks' eggs. Major Bendire (1892) 

 says: "Mr. C. J. Pennock has a set of five eggs in his collection, in 

 which the ground color is a rich bright green, and four of these eggs 

 are distinctly and handsomely marked. They were collected by him- 

 self near Kennett Square, Pennsylvania, May 2, 1887." 



The measurements of 62 eggs average 49 by 38.5 millimeters; the 

 eggs showing the four extremities measured 54 by 40, 51.5 by 42, and 

 43 by 34 millimeters. 



Young. — Incubation is shared by both sexes, does not usually begin 

 until all, or nearly all, the eggs are laid, and is said to last for 24 

 days. The young hatch at intervals of one or two days, perhaps 

 less, for there is very little difference in size noticeable among small 

 young. A brood that I watched and photographed w^ere still in the 

 eggs on June 4; on June 18, when probably 10 to 12 days old, their 

 plumage had not started to grow, but they were very bright, active, 

 and playful; only two of the four eggs had hatched; one egg was 



