176 THE CUCKOO 



no difficulty in carrying out the ordinary duties 

 of incubation and rearing of their brood. Such 

 is also the case with the American yellow-billed 

 cuckoo, which builds its own nest and rears its 

 own young ; yet Yarrell states, on the authority 

 of Audubon, that this bird also lays its eggs at 

 considerable intervals, so that eggs and young 

 at different stages of development are found 

 together. Like our own species it is a migrant, 

 and Pennant tells us that it arrives in New 

 York in May, makes its nest in June, and 

 retires from North America in autumn. 



In summing up the evidence, there does not 

 appear to be good ground for the theory that 

 the cuckoo seeks intentionally the nests of 

 species whose eggs resemble her own ; one of 

 the best German observers, A. Walters, having 

 compared no less than 214 cuckoo's eggs with 

 those of their foster-parents, with the result 

 that in only some six cases was there a strong 

 resemblance, while the great number bore no 

 resemblance whatever. As to whether the 

 mother cuckoo returns to the nest at hatching 

 time to turn out the eggs of the foster-parents, 

 the evidence seems in favour of the view that 

 sometimes, at least, she does so ; while on the 

 question of her devouring such eggs, Sachse 

 has proved that such has occurred, although 



