132 BIRD LIFE GLIMPSES 



exceptions — might be sufficiently persistent to lay an 

 egg in the completed nest of the starling. In this 

 latter case, at any rate, it seems more than likely 

 that the original parasite would become the dupe of 

 his ousted victim, "and thus the whirligig of time " 

 would have "brought in his revenges." 



Whether in speculating upon the various possible 

 origins of the parasitic instinct, as exhibited in per- 

 fection by the cuckoo, this one has ever been con- 

 sidered, I do not know, but it does not appear to me 

 to be in itself improbable. It is not difficult to 

 understand a bird seizing another one's nest, first 

 as a mere site for, and then, gradually, as its own. 

 That the dispossessed bird should still strive to lay 

 in its own appropriated nest, and, often, succeed in 

 doing so, is also easy to imagine ; and if this should 

 be its only, or most usual, solution of the difficulty, 

 it would lose, through disuse, the instinct of incuba- 

 tion, and become a cuckoo malgri lui. All feeling 

 of property would, by this time, be gone ; the para- 

 sitic instinct would be strongly developed, and that it 

 should now be indulged, at the expense of many, or 

 several, species instead of only one — once the robber, 

 but whose original theft would be no longer trace- 

 able — is a sequel that one might expect. In a process 

 like this there would have been no very abrupt or 

 violent departure, on the part of either species — of 

 the dupe or of the parasite — from their original 

 habits. All would have been gradual, and naturally 

 brought about. Therefore, as it appears to me, all 

 might very well have taken place. Let me add to 

 these speculations one curious fact in regard to the 

 two birds whose inter-relations have suggested them, 



