290 MR. E. C. STUART BAKER ON 



eggs and it would seem that whilst a few individual Cuckoos 

 have reached a very high degree of evolution in this respect, the 

 great majority are still only in its earliest stages. 



Leaving the European Cuckoo and moving farther east into 

 Asia, we find a very closely allied form , Gucuhos canortis telephonus, 

 apparently depositing eggs which are much further advanced in 

 evolution. Unfortunately, we have not much material to work 

 on but even among the few eggs I have seen of this bird — under 

 two hundred — there appear to be many cases of advanced 

 evolution. The most noticeable, perhaps, are to be fovind in the 

 very close i^esemblance between the eggs of the Red-backed 

 Shrike, Lanius schach erythronotus, the Spotted Forktail, 

 Enicurus maculatits maculatus and the eggs of the Cuckoos 

 which respectively victimize these two birds. 



Again, we find that Calliope seems to form a favourite fosterer 

 for this Cuckoo, and all the eggs placed in the nests of these birds 

 have a very distinct blue ground also, one or two being but very 

 faintly marked. 



These eggs were all taken in the extreme North- West of India, 

 but the farther east we work, the moi^e advanced the evolution. 

 In the Central Himalayas the two favourite fosterers seem to be 

 Trochaloptericm lineatum and Larvivora hrunnea, or, in certain 

 areas, /S'axicoZa torquata indica and Oreicola ferrea. The first two 

 birds lay unicoloured bright blue eggs, the last two, bluish eggs 

 very faintly marked with pale reddish. To go with these eggs 

 we have a beautiful blue egg evolved and it is seldom one finds a 

 Cuckoo's egg of any colour but blue placed in the nests of these 

 birds. Working yet farther east we come to another race of 

 Cuckoo, Guculus canorus hakeri, a very sedentary bird, breeding 

 at comparatively low levels and migrating for very short distances 

 into the plains in winter. 



As with the other races, so with this species, the number of 

 fosterers cuckolded is very la.rge, and we have no signs that 

 evolution has been in existence long enough to eliminate all but 

 those Cuckoo individuals which deposit their eggs in only the 

 nests of one, two, or a few of the bii'ds which are the most 

 suitable for the purpose of bringing up their young. We do, 

 however, find that normally, the number of species called upon 

 to rear the young Cuckoo is much more restricted than it is 

 farther west. For example, in Assam, nineteen out of twenty 

 eggs — perhaps a much greater percentage even than this — will 

 be found in the nests of the two genera Cisticola and Sioya, both 

 consisting of small Warblers which swarm all over the hills 

 above 4000 feet, or in the nests of Pipits. The Cisticolas are of 

 two species, C. c. cursiians, extremely common, and C. iytleri, 

 rather rare. The former lays a tiny white or bluish-white egg 

 speckled or spotted with reddish brown ; the latter lays a bright 

 blue egg boldly spotted with very dark brown. The eggs of the 

 Suyas vary much more, indeed they may be said to be poly- 

 morphic, for the ground colour may be white, pink, bluish, blue- 



