106 ANIMAL LIFE IN DESERTS 



survive prolonged exposure to the desert sun. 

 Though it is extremely difficult to disentangle truth 

 from fiction in the case of the wild ostrich, I think 

 that the following facts are now established. Neither 

 in Africa nor in Arabia do ostriches bury their 

 eggs in the sand, as is frequently stated. The 

 eggs are often left entirely uncovered and exposed 

 to the heat in the middle of the day, particularly 

 in the hotter parts of the bird's range. At other 

 times of the day, and particularly in the colder parts 

 of the bird's range, the eggs of the ostrich are 

 incubated by both parents in turn. 



Smaller eggs, which are more rapidly penetrated 

 by heat, are quickly killed under conditions which 

 merely serve to incubate the great eggs of the 

 ostrich. The existence of this danger was clearly 

 demonstrated during the fighting round Kut el 

 Amara, and in other places in Mesopotamia, where 

 many eggs of Sandgrouse were destroyed by the 

 sun because the parent birds were driven from 

 their eggs by gunfire. 



C. B. Ticehurst tells me that such eggs as those 

 of Geochelidon nilotica, Glareola pratincola. Sterna 

 caspia, and Larus gelastes are killed by exposure to 

 hot sun. These birds are not desert breeders, but 

 nest upon mud-banks under conditions which fre- 

 quently approximate to true desert during the 

 breeding season, and his observations are therefore 

 pertinent. 



The devices to which the parent birds resort 

 to avoid such fatalities are extremely interesting 

 because they are so varied. Many desert breeders 



