COOPER'S OAWK. 195 



Cooper's Hawks are persistent layers The loss of their first set does not 

 at all du courage them; in due time they will have a second, and if this is taken, 

 even a third one, each one usually smaller in number than the first clutch. 

 Some birds show great attachment to the original nesting site, and will continue 

 laying in the same nest, even after being repeatedly robbed; others abandon 

 the rifled nest each time and select a new site, generally in the same woods, 

 however. Mr. C. J. Pennock records taking a set of four eggs from the nest 

 of a Cooper's Hawk on April 24, 1874; May 5 two more eggs were taken 

 from the same nest, and on May 11 two others. Later m the season (about 

 August 1), on visiting the same locality, two young Hawks of this species were 

 seen, but it is not known if they were reared in the old nest. 1 



The eggs of Cooper's Hawk are deposited at intervals of one or two days, 

 and incubation does not begin until the set is nearly completed. 



Their ground color varies from a pale bluish white to a greenish white 

 tint, which fades out considerably in time. Occasionally a much higher tinted 

 set is found. 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 himself near 

 Keunett Square, Pennsylvania, May 2, 1887* 



While many of these eggs are perfectly immaculate, fully one-half of 

 those in the U. S. National Museum collection are spotted with irregular mark- 

 ings or scrawls of different shades of brown, drab, or fawn color. These 

 markings, in most cases, are rather faint and irregularly scattered over the 

 egg, usually heaviest about the larger end. 



The average size of sixty-two eggs in the U. S. National Museum col- 

 lection, from various parts of the United States, is 49 by 38.5 millimetres. 

 The largest egg of this series measures 51.5 by 42, the smallest 43 by 34 

 millimetres. 



Of the type specimens No. 23003, selected from a set of four eggs (PI. 

 5, Fig. 18), taken by First Lieut. H. C. Benson, Fourth Cavalry, U. S. Army, 

 near Huachuca, Arizona, May 12, 1887, shows the scrawls referred to above; 

 and No 23306 (PI. 5, Figs. 19 and 20), both from a set of five, taken by Mr. 

 Jerome Trombly, near Petersburg, Monroe County, Michigan, May 14, 1885, 

 show one of the better marked types, and an unspotted egg. Four eggs of 

 this set are distinctly spotted. These eggs were taken from an old Crow's 

 nest placed in the forks of a pin oak, a trifle over 40 feet from the ground. 

 The Hawks had simply repaired the inside of the nest, and lined it slightly 

 with a few dry leaves, a little moss, and shreds of bark. 



'Bulletin Nuttall Ornithological Club, Vol. in, 1878, p. 41. 



