202 BIRD BEHAVIOUR 



wings in both sexes (M. badius), which is also 

 common, and is not parasitic, except to the mild 

 extent of stealing another bird's nest when it 

 can ; this species is itself parasitized by another 

 (M. rufo-axillaris) in which both sexes are black. 



I particularize the colours of these species because 

 it is interesting to note that the one with the 

 simplest and probably most primitive coloration 

 retains its primitive habits, and the most advanced 

 in coloration is actually parasitic on this; a fact 

 which, however curious it may appear, is not so 

 paradoxical after all, for allied species recognize 

 each other's affinity, and as long as a member of a 

 parasitical group retained the ordinary nesting- 

 habits of birds, it is, after all, at least as reasonable 

 that a parasite should quarter itself on this as on 

 an alien. There is, however, no case known of a 

 parasitic Cuckoo quartering its offspring on an 

 independent one, although species of both types 

 are habitually found in the same countries in the 

 Old World. 



The one Cow-bird which penetrates into the 

 northern half of the American continent is, like 

 our exceptionally widely- ranging Cuckoo, a bird of 

 extended parasitism, favouring various species of 

 small Finches and insectivorous birds ; with the 

 Cat-bird (Galeoscoptes carolinensis), a larger species 

 than most of its fosterers, it is seldom successful, 

 and the Golden Warbler (Dendrceca estiva) some- 

 times disposes of the Cow-bird's egg, not by turning 

 it out of the nest, but by building a fresh floor over 



