The Yin-Yang of Pikas and Rattlesnakes

In many ways, pikas and rattlesnakes are polar opposites among North American animals.  The pika, of course, is a furry, warm-blooded (i.e., endothermic) mammal primarily thought of as a dweller of northern temperate mountainous zones.  And his seeming opposite, the rattlesnake, is a scaly, cold-blooded (i.e., ectothermic) reptile most associated with southern desert, arid and …