OF EASTERN PENNSYLVANIA. 215 



several nests. One was built on the summit of a species of 

 Finns, at a height of two feet, and consisted of small twigs 

 exteriorly, with a lining of moss. This nest contained two 

 young birds, one of the age of ten days, and the other that of 

 three weeks, besides an addled egg. The time of discov- 

 ery being June 2oth would carry the incubating period back 

 to the early part of May. Another structure was taken 

 April 28th. which was placed in the topmost crotch of a 

 lofty pine, and was built of dry sticks, with a lining of hay 

 and feathers. This nest contained a complement of six 

 eggs. A third structure possessed a lining of green mosses 

 and the hair of deer, and contained six eggs. In one sol- 

 itary instance, a complement of seven ova was discovered. 



According to Mr.'B. R. Ross, as quoted by Dr. Brewer, in 

 the region of Great Slave Lake, the nest is not exclusively 

 placed upon trees, but sometimes upon cliffs. Oviposi- 

 tion takes place either during the last of March, or the begin- 

 ing of April. The usual complement of eggs is set down 

 at four, although in one instance, he received a sat of 

 three. In the vicinity of Nulato, Mr. Dall found a nest as 

 early as May 5th, which \vas placed on the summit of an 

 old birch stump, at an elevation of fifteen feet. It was 

 nothing more than a mere excavation in the decayed wood, 

 upon the bottom of which six eggs were deposited. At 

 the time of its discovery, the male occupied the nest, the 

 female being notably absent. From this fact we infer that 

 the incubating process is mutually performed by the sexes. 

 While attempting to reach the structure, Mr. Dall was as- 

 sailed by the male bird, who knocked his cap from his head. 



The eggs of this Owl vary somewhat in size. One, which 

 was removed from the oviduct of the parent, on the i6th of 

 April, at Fort Simpson, by Mr. Ross, according to Dr. 

 Brewer, measured 1.50 by 1.20 inches. It was oval in 

 contour, and of an obscure white color. Another taken 

 by Mr. Macfarlane, at Fort Anderson, was rounded-oval, 

 with an equal bluntness at the extremities, and measured 



