FEATHERED GIANTS 129 



of circumstances will most naturally be found on islands 

 whose geological history is such that they have had 

 no connection with adjacent continents, or such a very 

 ancient connection that they were not then peopled 

 with beasts of prey, while subsequently their distance 

 from other countries has prevented them from receiv- 

 ing such population by accident in recent times and 

 has also retarded the arrival of man. 



Once established, flightlessness and size play into 

 one another's hands; the flightless bird has no limit 

 placed on its size' while granted a food supply and im- 

 munity from man; the larger the bird the less the 

 necessity for wings to escape from four-footed foes. 

 So long as the climate was favorable and man absent, 

 the big, clumsy bird might thrive, but upon the coming 

 of man, or in the face of any unfavorable change of 

 climate, he would be at a serious disadvantage and 

 hence whenever either of these two factors has been 

 brought to bear against them the feathered giants have 

 vanished. 



REFERENCES 

 There is a fine collection of mounted skeletons of various 

 species of Moas in the Museum of Comparative Zoology at 

 Cambridge, Mass., and another in the American Museum of 

 Natural History, New York. A few other skeletons and numer- 

 ous bones are to be found in other institutions, but the author is 

 not aware of any egg being in this country. Eggs of ^pyornis 

 may be seen in most of the large museums in the United States, 

 the prices ranging from £200 down to £30, this last being much 

 less than prices paid for eggs of the great auk. But then, the great 

 auk is somewhat of a fad, and there are just enough eggs in 

 existence to bring one into the market every little while. Besides, 



'While we do not know the hmit of size to a flying creature, none has 

 as yet been found whose wings would spread over twenty feet from tip 

 to tip, and it is evident that wings larger than this would demand great 

 strength for their manipulation. 



