152 FROM FISH TO PHILOSOPHER 



themselves as permanent residents. The sand grouse is 

 reported to hatch its eggs when the air is very dry and 

 the desert soil too hot to touch, the vegetation parched, 

 and the seeds all but desiccated. The adults fly long dis- 

 tances to watering groimds at regular intervals, and to 

 sustain the nestlings, the male, before drinking, rubs his 

 breast violently up and down on the groimd to ruffle the 

 feathers and then wades in to saturate his underparts; 

 when he returns to the nest the young, which hve on 

 dry seeds suppHed by the parents, get under him and 

 suck the water from the feathers by passing them 

 through their bills. Even more than the sand grouse, the 

 thrushes and desert larks appear to have achieved al- 

 most complete independence of a supply of drinking wa- 

 ter. The ostrich is perhaps as independent as any bird 

 and roams many miles away from water. Whereas other 

 birds, whose eggs are smaller and heat more rapidly, 

 must nest upon them during the day to keep them from 

 being cooked, the ostrich buries its eggs in exposed sand, 

 the surface temperature of which may reach 125° F. or 

 higher— presumably only the large size of the egg keeps 

 it from being roasted. 



The desert invariably presents an elaborately inter- 

 related pyramid of vegetable and animal life. At its 

 worst, when moisture is at the greatest premium, it may 

 seem to be devoid of any living thing except cacti, 

 dried-up sagebrush and a few scrubby plants; but even 

 then one can generally discover under a large flat stone 

 a population of wood lice, centipedes, millepedes, spi- 

 ders, scorpions, mites, cockroaches, crickets, beetles, 

 bugs, ants, snails, and earthworms, and even an occa- 

 sional Hzard, snake, or frog. Then, with the first increase 

 in moisture, these creatures venture from under cover 

 and the woodpecker comes to feed upon them, and to 

 hew out a nesting place in the giant cactus; and when 

 the woodpecker abandons the nest after its breeding sea- 

 son, owls and other birds come to occupy it, honeybees 

 use the empty nests as hives, insect scavengers survive 



