of living flightless birds, and birds that are well on the way to 

 this condition, will afford us a ready answer. 



Whenever we find birds Uving, so to speak, lives of 

 languorous ease — ^where there are no enemies to be evaded, 

 where there is an abundance of food to be picked up on the 

 ground all the year round, and the climate is kindly, there 

 flight is no longer practised. Year by year, generation after 

 generation passes by, and no use whatever is made of the 

 wings. In aU such cases these once most vital organs dwindle 

 away, and finally vanish. We can trace every step in this 

 process of decay. 



We may begin with the " steamer-duck " of the Falklands. 

 In this species, after the first moult, the power of flight is lost 

 for ever. Among living birds only a few species, apart from 

 the ostrich-tribe, are in this dolorous case. The owl-parrot, 

 or kakapo, of New Zealand, is one of tliese. A grebe found 

 only on Lake Titacaca, perched high up a mountain-side, 

 is another. In both these birds the keel of the sternum is 

 represented by the merest vestige, the breast-bone being 

 reduced to the condition found in the ostrich-tribe. 



The two giant pigeons, the dodo, and its cousin the 

 solitaire, afford instances where the loss of flight has been 

 followed by extinction, owing to the invasion of their haunts, 

 through the agency of man, by pigs and other domesticated 

 animals, which destroyed their eggs and young. 



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