156 AN AUSTRALIAN BIRD BOOK. 



Nature-students, who have a name for every native animal and 

 plant, called it the "Stranger." Its presence has heen 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 spreading 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 the Blight-Bird. 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 Lorikeet was very difficult 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. 



