THE COLOURS OF DESERT ANIMALS 147 



Grinnell has recorded a similar phenomenon. 

 Speaking of " conies " (Ochotona), by which an animal 

 very different from the bibHcal cony or hyrax is 

 meant, he says, " as elsewhere, the conies in the 

 white momitains live in rock sUdes and broken-up 

 rock out-crops." Two colours of rock occur in this 

 range, a blackish or dark red ' shale,' and a white 

 or greyish white granite. There are extensive belts 

 purely of one or the other kind of rock. Our party 

 took pains to shoot conies from each colour of 

 ground, keeping notebook record of where each 

 specimen was shot. I am unable to detect any 

 difference in colour between animals shot from white 

 granite and those from dark ' shale.' " 



Speaking of the Roadrunner {Geococcyx californi- 

 anus), a large, ground-loving Cuckoo found in 

 California, he remarks that "it is, of course, a 

 remarkable exception if the Roadrunner, a terrestrial, 

 permanently resident bird of all the areas it inhabits, 

 should not show some geographic colour pecuHarities. 

 Lideed, it is all the more strange that it does not show 

 conspicuous differences in colour tone in the arid 

 and subhumid areas it occupies, when we observe 

 the remarkably different colour tones exhibited by 

 the thrashers, towhees, spermophiles and jack 

 rabbits of the same areas, these also being terrestrial 

 animals. The Roadrunner's failure to conform to 

 the rule offers a problem for those who would explain 

 animal coloration whoUy on the ground of physio- 

 logical response to meteorological conditions, irre- 

 spective of adaptive value." 



Certain desert insects attain a silvery or sandy 



