NESTS AND NEST-BUILDING IN BIRDS 247 



Though such supports as the last named are good for robins, 

 they would be very poor for cuckoos in relation to their feeding 

 and other habits, and would never be taken. Such, moreover, 

 might not appeal to certain robins, when the circumstances 

 of their birth or experience had led them far from the haunts 

 of man. 



The black-billed cuckoo {Coccygus erythropthalmns) so far as 

 I have observed in central New Hampshire builds only in sapling 

 white pines, stunted crabs and thorn apple bushes, the total 

 recorded variation in height of nest in this species for the entire 

 country being only i6 feet (25 inches to 18 feet). This remark- 

 able constancy in position, or as to height and immediate environ- 

 ment, is plainly determined by the habits of the birds when on 

 their breeding and feeding grounds. We have only to recall the 

 stealthy, stalking manner of life of this cuckoo, which keeps 

 near to the ground, and inhabits pastures or brush grown places 

 where such trees and shrubs as I have mentioned abound and 

 afford the necessary support and concealment which are invariably 

 sought; in such places also they secure their prey, and their 

 young can climb about in comparative safety until ready for 

 flight. 



The swift of North America has been often cited as a remark- 

 able example of a bird which has changed its nesting habits in 

 recent times. Formerly breeding in hollow trees, and still doing 

 so in remote places, it now regularly resorts to the abodes of 

 man and glues its wicker nests (see fig. 8, part I) to the inside 

 of chimneys. Both the barn and eaves swallows, and indeed 

 many other species are in like case, but we cannot accept the 

 view that the habits of any of these birds have essentially changed 

 since the advent of white men to this continent three hundred 

 years ago. The swift indeed, shows a remarkable uniformity 

 and precision in its instincts which have remained unaffected 

 by the presence of man, the boasted change referring merely to 

 the position of the nest in artificial as distinguished from natural 

 structures. These birds, like hundreds of others, come to the 

 clearings and to towns for their food, and like them also, merely 

 adapt the altered physical conditions to their established needs. 

 Like the stork nesting on the housetop, or the osprey on the 

 cart wheel set horizontally on a high pole, or indeed the purple 

 martin or the bluebird, which take kindly to the house provided 



