PARASITISM OF CUCKOOS 



actually does is broadly this. The eggs are produced 

 rather continuously, so that the bird could not very 

 well place them all in one nest and then proceed to the 

 duties of incubation. The process would be too long 

 for the life of the parent. Thus it has had recourse 

 to its well-known habit. In accordance with the varied 

 hospitality upon which the cuckoo insists, the eggs vary 

 greatly in colour ; but whether there is always a cor- 

 respondence between the nest selected and the colour 

 of the eggs laid therein is not so certain. It has been 

 suggested that individual cuckoos acquire the habit of 

 laying their eggs in the nests of a given species, or even 

 for a series of seasons in the nests of the same individual. 

 That therefore the eggs, by a process of elimination, 

 get to be like those of the adopted foster parent, and 

 that the variety of egg coloration in the cuckoo is a 

 matter of individual cuckoos, and not individual eggs 

 of the same cuckoo. It is furthermore plain that the 

 young cuckoo is stronger and more muscular than its 

 fellow nestlings and that it actually does forcibly eject 

 them. But this predatory instinct on behalf of its 

 young is not universal in the cuckoo tribe. All the 

 immediate allies of the Cuculus canorus'oi our islands 

 are parasitic. But Eudynamis is the one exception 

 apparently among the group of cuckoos to which it 

 belongs that shows this characteristically cuculine habit. 

 This shows of course that the habit is but a recent one, 

 a point of view that is supported by the rare occurrence 

 (one case at any rate has been authenticated), of 

 common cuckoos building a nest of their own, and 

 attending to their own offspring The lark-footed 

 cuckoo (Centropus), usually to be seen in the Zoo, is not 

 parasitic. Now it is interesting that this cuckoo, like 

 some others which are equally independent of the 

 assistance of other birds, lays a white egg. The para- 

 sitic species have apparently all of them spotted and 



