OF EASTERN PENNSYLVANIA. 203 



the size of the little finger, for a framework, and is lined with 

 dry grasses, fern leaves, and not uncommonly, with the feath- 

 ers of birds that have been taken as prey. In the nests which 

 we have seen and examined in sitii, there were no indica- 

 tions of feathers that had been plucked from the breast of 

 the mother-bird. At a distance, the nest presents a close 

 resemblance to that of Corpus Americanus, and to those of 

 a few of our commonest Falcon idee. The base is from fif- 

 teen to sixteen inches in diameter, and the height from eight 

 to ten inches. The cavity is exceedingly superficial. The 

 period of nidification ranges from two to three days. The 

 labor is mutually performed by both birds, although the female 

 seems to control the operations. The male mostly gathers 

 the materials, and adjusts them to their places, subject how- 

 ever to the commands of .his partner. The latter will often 

 remove an article to another position, when once fixed, if 

 she deems it needful. The labor is chiefly performed at 

 night, although we have known instances in the midst of 

 deep forests, where some portion of the day was devoted to 

 the task. The work is intermittent in character ; the birds 

 working with commendable perseverance and diligence for 

 an hour or so, then relieving the irksomeness of the task, by 

 starting oft in quest of food, or of pleasure. A brief period 

 thus spent is necessary to recuperate their wasted energies, 

 and give renewed zeal. Several times during the course of 

 the night, do they alternate between feeding and building- 



The nest being finished, after a brief period of relaxation 

 for a day or two, the female begins to oviposit. The com- 

 plement of eggs varies from four to six. The eggs are 

 deposited at the rate of one egg per day, and invariably on 

 each consecutive dav. This task being over, the female 

 begins to incubate. In this she is assisted by her partner, 

 who contributes his share of the labor. When either bird 

 is disengaged from this business after having sufficiently sat- 

 isfied appetitive demands, it takes a position near to the nest, 

 ready to relieve its occupant when the time at length arrives. 



