186 BULLETIN 17 0, UNITED STATES NATIONAL MUSEUM 



Dr. Louis B. Bishop has sent me his notes on two mixed sets of eggs 

 of these two species, which he collected near New Haven, Conn., in 

 the same tract of woods in two different years. He had collected 

 seven sets of eggs of the hawk there during previous years. The 

 first nest contained three eggs of the hawk and one of the owl, the 

 former somewhat advanced in incubation and the owl's egg fresh. 

 The owl was on the nest, and the nest contained many downy feathers 

 of the owl, but none of the hawk. This nest was about 300 yards 

 from a nest often used by the hawks, from which he had once taken 

 a set of barred owl's eggs. The second nest was found the following 

 year, and probably the same birds were responsible for it. It con- 

 tained two eggs of the hawk and one of the owl, all somewhat ad- 

 vanced in incubation; the hawk was incubating. It would be inter- 

 esting to know whether both species would share in the incubation 

 and in the care of the young. 



Judge John N. Clark (1887) writes of a nest near Saybrook, Conn., 

 built by a Cooper's hawk, 80 feet from the ground in a giant chestnut 

 tree, which was occupied during four successive years by the Cooper's 

 hawk, a great horned owl, a red-tailed hawk, and a barred owl. 

 Walter A. Goelitz (1916) found a barred owl nesting in a hollow stub 

 within 5 feet of an occupied nest of a red-shouldered hawk, in Piatt 

 County, 111. William W. Rubey (1927) tells of a pair of barred owls 

 that nested in a wooden packing box put up in a tree by boys: "The 

 tree stood in a small, open grove, surrounded by houses and streets, 

 and only 90 feet from a large residence. The box {!){ by l)i feet, open 

 above and 2 feet deep) was mounted 24 feet above the ground in a 

 large tulip tree, and could be reached by rungs nailed to the trunk." 



Eggs. — The northern barred owl lays ordinarily two or three eggs, 

 oftener two than three, and rarely four. Three eggs seem to be 

 commoner in western sets and two eggs in eastern sets. In my 38 

 nests were 28 sets of two, 8 sets of three, and only 2 sets of four. 

 Of 23 sets in the J. P. Norris collection, 13 are sets of two and 10 sets 

 of three; this includes 4 sets of three and 2 sets of two from Iowa. 

 There is a set of five in the United States National Museum, but it 

 may have been laid by two birds. The eggs are oval or rounded-oval 

 in shape; the shell is more or less granulated, slightly rough to the 

 touch, and not glossy. The color is pure white. The measurements 

 of 82 eggs average 49 by 42 millimeters; the eggs showing the four 

 extremes measure 55.5 by 44, 52 by 45, and 42.5 by 37.5 millimeters. 



Young. — The incubation period is said to be between 21 and 28 

 days; I suspect that the latter figure is more nearly correct. The 

 female is supposed to do most of the incubating. Only one brood is 

 raised in a season, but, if the first set of eggs is taken, a second set will 

 be laid about three or four weeks later; sometimes even a third set 

 may be laid. 



