PROTECTIVE MIMICRY. 239 



show tliat Garrod's suppositions are tenable, we shall have 

 here a resemblance which may be in reality based upon affinity. 

 It is difficult to see what particular advantage a cuckoo could 

 secure for itself, by having become like a pheasant, unless 

 the spurs of the cock bird are known to their enemies, and 

 associated in their minds with the gallinaceous build and 

 coloration. 



But the cuckoos do not only present resemblances to the 

 pheasant tribe. The cuckoos themselves form a very hetero- 

 geneous group of birds ; their internal structure is not by any 

 means so uniform as in other restricted groups. Coupled with 

 these internal differences are many external differences, which 

 are not merely those of colour. No one would suspect that 

 the Ani of America, with its glossy black plumage and its 

 beak " resembling an immense Roman nose," was a member 

 of the same group as our somewhat hawk-like Cuculus 

 canorus. 



Messrs. Sclater and Hudson quote Azara to the effect that 

 this cuckoo (Crotophaga ani) " follows the cattle about in 

 the pastures like the cowbird." The cowbird (Molothnis 

 bonariensis) has a black plumage like that of the Ani, and 

 is of about the same size; they are both common, otherwise 

 it would be tempting to adduce this as an example of true 

 mimicry. 



Mr. Frank Finn has, at my suggestion, collected together 

 a number of cases where birds belonging to different orders, 

 and often living in different countries, show superlicial re- 

 semblances. He has kindly furnished me with the following- 

 instances. 



Sir Walter Buller, in the new edition of his " Birds of New 

 Zealand," speaks of the striking resemblance between the 

 cuckoo, Eudynamis taitensis, and an American hawk, Accipiter 



