Mimicry in Birds 379 
Our common domestic birds show by their casual variations the great changes in 
appearance, by variation alone, which might produce under favourable circumstances a 
serviceable mimetic resemblance; thus the common fowl often exhibits a variety in 
which the body is white and the primary quills and tail black, a coloration very 
characteristic of many large and powerful birds. 
Applying this to the stock case of the Orioles, we may compare the hypothetical 
ancestor of these birds with the known Canary. This bird is normally, in its 
wild state (and often in domestication), of a streaky olive-green, somewhat like the 
young of many orioles; it frequently produces a cinnamon form, and (very rarely) a 
brown one, which may be compared to the mimicking orioles, and everyone knows its. 
yellow and pied variations, one of which, the nearly extinct “London Fancy” breed, 
has dark quills and tail, and so very closely approaches the Golden Oriole’s plan of 
coloration. 
Now there is one oriole, the Australian Oriolus viridis, which is throughout life: 
green and streaky, and may be taken as representing the ancestor; and this shows 
not the slightest resemblance to the common Australian friar-bird (Lropidorhynchus 
cormiculatus), which has the usual snuffy-brown of his relatives, and a head altogether 
bald and black; in fact he is the typical friar. 
He is evidently a hopeless model for the green oriole, although as warlike, and 
therefore as desirable in that capacity, as the insular members of his family; but 
even if a brown variation occurred in Australian orioles they would have nothing to 
pass off as the friar’s bald black head. Possibly, too, the brown variation has never 
occurred, so the orioles have to get along on their own merits. The mimicking 
species in the islands further west have evidently been more fortunate, as the friar- 
birds there not being bald-headed, their garb was more easily counterfeited. 
Further west again the range of the friar-birds ceases, and here the orioles blaze 
out in black and gold, and even black and scarlet; nature not having bred them to: 
a dingy model the natural tendency of a green coloration to sport into yellow, and 
of brown to produce red (as shown in the brown Kaka Parrot (Nestor meridionalis) of 
New Zealand) has had free play. It is noticeable that these richly-coloured orioles 
have longer wings than the dull mimetic forms, so that imcreased power of flight has 
HAWK-CUCKOO. 
