BIRDS AS BROOD-PARASITES 



187 



this peculiarity of theirs has already been dwelt upon. Enough 

 to say here that the egg of the parasite is introduced into the 

 nest of the dupe, and after the necessary incubation by the fond 

 fool of a foster-mother the interloper successfully counterfeits the 

 heirs, who perish miserably, victims of his superior strength. 

 The whole process has been often watched, but the reflective 

 naturalist will pause to ask how such a state of things came 

 about, and there is not much to satisfy his enquiry. Certain it 

 is that some birds, whether by mistake or stupidity, do not un- 

 frequently lay their 

 eggs in the nests of 

 others. It is within 

 the knowledge of 

 many that Pheasants' 

 eggs and Partridges' 

 eggs are often laid in 

 the same nest, and it 

 is within the know- 

 ledge of the writer 

 that Gulls' eggs have 

 been found in the 

 nests of Eider- Ducks, 

 and vice versa] that a 

 Redstart and a Pied 

 Fly -Catcher, or the 

 latter and a Tit- 

 mouse, will lay their 

 eggs in the same con- 

 venient hole the forest being rather deficient in such accom- 

 modation; that an Owl and a Golden -Eye will resort to the 

 same nest-box, set up by a scheming woodsman for his own 

 advantage; and that the Starling, which constantly dispossesses 

 the Green Woodpecker, sometimes discovers that the rightful 

 heir of the domicile has to be brought up by the intruding tenant. 

 In all such cases it is not possible to say which species is so 

 constituted as to obtain the mastery; but just as it is conceivable 

 that in the course of ages that which was driven from its home 

 might thrive through the fostering of its young by the invader, 

 and thus the abandonment of domestic duties would become a 

 direct gain to the evicted householder, so the bird which, through 



Fig. 1132. Young Cuckoo (Cuculus canorus) ejecting a Fledgling 

 Meadow-Pipit from the Nest 



