OF WILD ANIMALS 163 



I think that the animal psychologists have lost much by so 

 completely ignoring these brain-busy animals, and I hope that 

 in the future they will receive the attention they deserve. 

 Why experiment with stupid and nerveless white rats when pack 

 rats are so cheap? 



It was in the wonderland that on the map is labeled "Ari- 

 zona" that I met some astonishing evidences of the defensive 

 reasoning power of the pack rat. In the Sonoran Desert, where 

 for arid reasons the clumps of creosote bushes and salt bushes 

 stand from four to six feet apart, the bare level ground between 

 clumps affords smooth and easy hunting-grounds for coyotes, 

 foxes and badgers, saying nothing of the hawks and owls. 



Now, a burrow in sandy ground is often a poor fortress; and 

 the dropping spine-clad joints of the tree choyas long ago sug- 

 gested better defenses. In many places we saw the entrance of 

 pack rat burrows defended by two bushels of spiny choya 

 joints and sticks arranged in a compact mound-like mass. In 

 view of the virtue in those deadly spines, any predatory mam- 

 mal or bird would hesitate long before tackling a bushel of 

 solid joints to dig through it to the mouth of a burrow. 



Did those little animals collect and place those joints because 

 of their defensive stickers, — with deliberate forethought and 

 intention? Let us see. 



In the grounds of the Desert Botanical Laboratory, in 

 November 1907, we found the answer to this question, so 

 plainly spread before us that even the dullest man can not ignore 

 it, nor the most skeptical dispute it. We found some pack rat 

 runways and burrow entrances so elaborately laid out and so 

 well defended by choya joints that we may well call the en- 

 semble a fortress. On the spot I made a very good map of 

 it, which is presented on page 164.* The animal that made it was 

 the White-Throated Pack Rat {Neototna alUgula). The for- 

 tress consisted of several burrow entrances, the roads leading 

 to which were defended by carefully constructed barriers of 

 cactus joints full of spines. 



•Jtom "Camp-Fires on Desert and Lava" (Scribner's) page 304, 



