156 
AN AUSTRALIAN BIRD BOOK. 
Nature-Students, who have a name for every native animal and 
plant, called it the "Stranger." its presence has been accounted 
for by some authorities as being due to the fierce winds that 
accompanied Black Thursday having blown it over from Aus- 
tralia. However, not satisfied with spreadijig throughout New 
Zealand until it is said to be the commonest bird there, it has 
spread out to Chatham Island, and a flock was reported recently 
a considerable distance from the coast, apparently looking for 
fresh fields, or rather islands, to colonize. it is a well-known 
city dweller. Though it destroys grapes and other soft fruits, 
it also so completely destroys aphides that it is appropriately 
called tne Blight-iiird. Again, the balance is strongly in its 
favor, for it is probably but taking fair toll of that which will 
probably not have reached maturity but for its labors, and the 
laborer, even if a bird, is worthy of his hire. 
A bird's color usually affords it protection from its natural 
enemies. These are mainly birds of prey flying overhead. 
Thus, speaking generally, protective coloration applies only to the 
upper surface, so that a white throat or under surface does not 
necessarily render a bird conspicuous to its natural enemies. 
Again, a bird may be very conspicuous when seen away from 
its natural surroundings, but the concealment may be perfect 
under natural conditions. It has been already mentioned that 
the gorgeous Blue Mountain I^orikeet was very diflacult to discern 
in its native sugar-gums. A tiger is said to be invisible at a 
distance of ten yards in a jungle; the black stripes being similar 
to the shadows of the bamboos, and the light bands to the 
sunlight between the vegetation. 
The White-eye and Tree-Creepers just noticed may be considered 
protectively colored, for they are difficult to see in a tree. Still, 
the brown patch on the wing of the Tree-Creeper is conspicuous 
as it flies. Alfred Russel Wallace, the great evolutionist, sup- 
plied a good explanation, when he regarded bright wing bands, 
white rump, and white-tipped tail, as "warning colors." An 
enemy is, perchance, perceived by a bird. This individual flies 
away quietly; others see the bright wing patch disappear, 
and they seek shelter as quickly and quietly as possible. This is 
often a great advantage, for, in many cases, all reach safety, pos- 
sibly, before the enemy has seen one of them. If the first bird 
had given an alarming call, it would have warned the enemy too. 
It is noteworthy that these bright markings on the upper sur- 
face are, usually, not visible when the bird is at rest. The white 
wing patch folds in, the white rump is covered, while, in a white- 
tipped tail, it is usual for the two centre feathers to be plain 
throughout (see illustrations of species 313 and 329). The tail 
is folded, and the white tips are covered by the two non-white 
centre feathers. The introduced Indian Turtle-Dove, common 
about nearly every city in Australia, shows the spread-out, white- 
tipped tail splendidly when flying. The bird itself is barely 
visible if it settles in the shade or on the soil. The Indian Myna 
a city bird, has both white wing-patch and white-tipped tail. 
