American Os prey. 249 



would lead these birds to fly to the assistance of a distressed 

 companion would certainly induce them to co-operate with 

 their brethren in the difficult task of nest-building, especially 

 when such a bulky structure as the species is known to con- 

 struct would severely task both the time and patience of the 

 pair which is to occupy it. The vast amount of labor and 

 time expended in rearing such a fabric is a sufficient induce- 

 ment for them not to want to indulge in such employment 

 any more than is absolutely necessary. Hence these nests 

 are constructed for durability. Unlike his European con- 

 gener, whose nest is placed upon a high cliff, the O'sprey 

 almost invariably builds on trees. All nests taken by the 

 writer have seldom been at a greater elevation than fifteen 

 feet, although instances have been recorded where they were 

 twice that height. It is a remarkable fact that the trees sup- 

 porting these nests are always dead and generally placed 

 in the midst of marshy ground, either completely isolated 

 or surrounded by a dense growth of bushes. At all events, 

 they occupy rather conspicuous positions. It is probable 

 that the excrement of the birds or the saline character of 

 their food has much to do with killing the nesting-trees. 

 Trees which seem vigorous and thrifty at first manifest after 

 a year's occupancy unmistakable signs of death. Not always 

 are trees selected for nesting purposes, for a Mr. W. H. 

 Edwards describes a nest built on a tall cliff on the banks of 

 the Hudson River, not very far from West Point. 



Externally the nest is composed of large sticks piled to a 

 height varying from two to five feet, and measuring fully 

 three feet in diameter. Corn-stalks, mullein-stocks and bark 

 are occasionally intermingled with the sticks, but within 

 there is a rather profuse lining of sea-weed and the long 

 grasses which grow so luxuriantly in salt-water marshes. 

 The cavity ranges from fourteen to fifteen inches in diameter, 

 and is unusually shallow in proportion to the size of the nest. 



Three eggs constitute the usual nest-complement, although 

 two are sometimes laid, and rarely four, and these are 



