FEATHERED GIANTS 155 
dwelt in peace before the advent of man. 
And the same things are true of the Moas, the 
Mpyornithes, the flightless birds of Patagonia, 
the recent dodo of Mauritius and the solitaire 
of Rodriguez, each and all of which flourished 
in places where there were no men and prac- 
tically no other enemies. Hence we deduce 
that absence of enemies is the prime factor in 
the existence of flightless birds,* although 
presence of food is an essential, while isolation, 
or restriction to a limited area, plays an im- 
portant part by keeping together those birds, 
or that race of birds, whose members show a 
‘tendency to disuse their wings. It will be 
seen that such combinations 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 coun- 
tries has prevented them from receiving such 
* Note that in Tasmania, which is very near Australia, both 
| in space and in the character of its animals, there are two car- 
 nivorous mammals, the Tasmanian “ Wolf” and the Tasma- 
nian Devil, and no flightless birds. 
