114 



ANIMALS OF LAND AND SEA 



243 



244 



241 



regions therefore are especially adapted to the development 

 of the soaring habit. The uprush of air due to deflection of 

 the winds makes soaring possible on cloudy days, and in the 



far north and south 

 under conditions 

 which would prevent 

 it on fiat land where 

 the only updraughts 

 are the resultof 

 heating. 



Mountainous re- 

 gions always harbor 

 many soaring birds. 

 As a fruit-eating bird 

 would derive no ad- 

 vantage whatever 

 from the practice of 

 soaring, all fruit be- 

 ing far more visible 

 from below or from 

 the side than from 

 above, and also sta- 

 tionary, the soaring 

 birds of mountainous 

 regions are mostly 

 predaceous or car- 

 rion feeders, or a 

 combination of the 

 two, or quite om- 

 nivorous. They in- 

 clude eagles, vul- 

 tures, hawks and 

 ravens, and because 

 of the great advantage that they have in being able with a 

 minimum of exertion to survey a vast amount of territory and 

 thus to detect a maximum amount of food, the largest of the 



Figs. 240-245. Early stages of West Indian 

 Fire-flies. 



For explanations of the figures see p. xviii. 



