The drongo is blue and black and is, he believes, warningly coloured.
He found that a South African drongo (Dicrurus (Buchanga) assimilis) was rejected after one or two attempts to eat it by a hungry mongoose (Herpestes galera) which had been starved for purposes of the experiment.
Pheasants, ducks, geese and snipe are abundant, and Dr C. Collingwood in his Naturalist's Rambles in the China Seas mentions .Ardea prasinosceles and other species of herons, several species of fly-catchers, kingfishers, shrikes and larks, the black drongo, the Cotyle sinensis and the Prinia sonitans.
Another species of this group, the black cuckoo of India, apparently mimics the black drongo-shrike (Dicrurus ater), the resemblance between the two species being very close.
The drongo is a fierce and powerful bird which will not tolerate a strange bird of the size of a cuckoo near its nest, yet on account of its resemblance to the drongo, the hen cuckoo is enabled, it has been claimed, to lay her egg in the nest of the drongo, which mistakes the cuckoo for one of its own kind.
This suggests that the resemblance to the pugnacious drongo may be beneficial in protecting the defenceless cuckoo from enemies.