Adaptation in Parasitic Cuckoos' ^iW^' 389 



in some cases the Cuckoo's egg being liardly distinguishable 

 from that of the fostei'-parent. 



Birds far less often imposed upon than the above-men- 

 tioned Warblers and Pipits are the Silver-eared Mesia and 

 the Red-billed Liothrix, yet we find very beautiful cases of 

 adaptation to the eggs of these birds. Both species lay eggs 

 which have normally quite a bright, pale blue ground-colour, 

 spotted, often quite richly, with deep reddish brown and 

 purple-black; yet different as these are from any common 

 type of Cuckoos' eggs, I have taken quite a number of well- 

 matched blue or bluish Cuckoos' eggs from their nests. The 

 inference to be drawn here is that as a class Mesia argent- 

 auris and Liothrix lutea are intelligent birds, and accordingly 

 refuse to sit on ill-matched eggs more often than most other 

 birds do. 



The eggs of Baker's Cuckoo are rarely found in the nests 

 of other Babblers, though they may at odd times be met with 

 even along with eggs so unlike their own as those of the 

 Scimitar Babblers or of the little Alcippe. 



A good many Cuckoos place their eggs in the nests of 

 Shrikes ; and here again adaptation has proceeded further on 

 the road to com[)letion than in most cases, doubtless for the 

 same reason as with the genera Mesia and Liothrix^ the 

 process of elimination of wrongly coloured eggs being con- 

 ducted by the foster-parents with more regularity and 

 discretion. Many clutches of this species containing 

 Cuckoos' eggs are beautiful examples of adaptation, whilst 

 the contrast in the others between the lawful and the adopted 

 eggs, if considerable, is seldom violent. 



Flycatchers, more esj)ecially those of the genera ^toparola, 

 Niltava, and Cyornis, are fairly frequently cuckolded, and the 

 Cuckoos' eggs, in many cases, agree well with those of the 

 fosterers named, and have probably already advanced a con- 

 siderable way towards perfect adaptation ; but at the same 

 time they are still often wrongly coloured, and when deposited 

 in the nests of Bhipidura and certain other Flycatchers, as 

 they occasionally are, it can only be said that the parent 

 Cuckoo must have placed them there by mistake, or because 



