THE DRONGO AND ITS MIMIC 203 



it, and in the case of a repeated invasion by the 

 parasite, may have recourse to this expedient more 

 than once. 



Another case of parasitism, and in this case also 

 on allies, is furnished by the Troupials, the large 

 black Cassidix oryzivora, a bird about the size of 

 a Jackdaw, being a parasite on some of the other 

 Troupials known as Hang-nests. 



Cow-birds do not mimic their dupes in appear- 

 ance any more than Honey-guides ; and indeed 

 this resemblance to an alien fosterer only appears 

 in one or two Cuckoos, and is doubtful there. One 

 Eastern Cuckoo, indeed (Surniculus dicruroides), has 

 been called the Drongo-Cuckoo, and attained a 

 great celebrity in books and museums, owing to 

 its resemblance to the common, conspicuous, and 

 highly pugnacious black Drongo-Shrikes (Dicrurus), 

 which it is believed to parasitize, though the chief 

 evidence of this is that a pair of Drongos has been 

 seen to kill one of these Cuckoos, which does not 

 look as if the resemblance did much good to its 

 possessor. 



The size and general shape of Drongo and 

 Drongo-Cuckoo are certainly very similar, but after 

 all there are plenty of birds of which this could 

 be said ; the black colour goes for nothing, as 

 there are several other black Cuckoos, parasitic and 

 otherwise, such as Cuculus clamosus allied to our 

 Cuckoo, Coccystes serratus among the crested para- 

 sitic Cuckoos, and the whole genus Crotopbaga or 

 Anis among the non-parasites. Moreover, the tail 



