SMALLER MAMMALS OF NORTH AMERICA 



393 



be rewarded by the appearance of the pika on 

 the top of a stone near the mouth of its retreat. 



After a time, if everything is quiet, it re- 

 sumes its scampering about over the rocks or 

 may come to the border of the slide and make 

 little excursions across the open ground after 

 some of its forage plants. Skipping nimbly 

 from the border of the slides to neighboring 

 patches of vegetation, sometimes fifty or more 

 feet away, the pika nips off the stems of short 

 grasses or other plants and taking them up, 

 like small bundles, crosswise in its mouth, runs 

 back to add them to its "stacks." These sallies 

 are quick little runs, made as though in fear of 

 being long away from the safety of the rocks. 

 Caution is needful, however, in a world where 

 lurk such enemies as coyotes, lynxes, foxes, 

 weasels, hawks, and owls. 



During late summer the pikas have the extra- 

 ordinary habit of gathering stores of small 

 herbage in piles containing sometimes a bushel 

 each, usually well sheltered in dry places under 

 the rocks where they live. Pikas are active all 

 winter, and these little stacks of well-cured hay, 

 containing a great variety of small plants, 

 serve them as food during the severe cold sea- 

 son, when at these high altitudes they are 

 buried under many feet of snow. 



In pleasant weather, near the end of summer, 

 visitors to the mountains of Colorado, Glacier 

 National Park, the high slopes of Mount 

 Shasta, or of the Sierra Nevada may have the 

 pleasure of watching the pikas hard at work 

 doing their "haying." One of their "stacks" 

 in the mountains of New Mexico contained 

 thirty-four kinds of plants, including many 

 flowers. No one who once becomes acquainted 

 with these unique and gentle little animals will 

 ever cease to remember them with friendly in- 

 terest. 



THE PORCUPINE (Erethizon dorsatum 



and its relatives) 



{For illustration, see page 412) 



The porcupine is one of the most grotesque 

 of the smaller North American mammals. 

 With a weight of from fifteen to twenty 

 pounds, its heavy body is supported on short 

 legs, the feet resting flat on the ground like 

 those of the raccoon, instead of on the toes, as 

 in most small animals. 



Its strongest peculiarity is the specialized 

 development of most of the fur into rigid, 

 sharp-pointed spines or "quills" from half an 

 inch to over three inches in length. That the 

 spines represent the underfur of ordinary 

 mammals is evident from the fact that they 

 are overlaid by long, coarse guard hairs, some- 

 times several times their length. 



The spiny armament usually lies flat on 

 the body, but when the animal is excited or 

 alarmed it may be raised, by special muscles 

 on the underside of the skin, into a bristling- 

 array of barbed points. The spines are so 

 slightly attached that when their points enter 

 the skin of an enemy they at once become free 

 at the base. The points firmly set in the skin 





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THE TRAIL OF A FIELD OR MEADOW MOUSE 



When compared with that of the deermouse, 

 one notes the absence of the tail mark and the 

 rarity of the fore feet being paired (see pages 

 403 and 420). 



of another animal, the spines can be withdrawn 

 only with considerable effort, and if left will 

 gradually work deeper and may traverse a 

 considerable part of the victim's body before 

 Anally becoming encysted. 



When assailed the porcupine turns down its 

 head, arches its back, and, on firmly planted 

 feet with all its spines erected into a bristling 

 cover, awaits the enemy. The instant its body 

 is touched the club-shaped tail, armed with 

 a multitude of spines, is swung vigorously 

 around and the animal so incautious as to re- 

 ceive the blow is pierced by a host of stinging 

 darts which, freed from the porcupine, remain 

 to torment the aggressor. This swift and ef- 

 fective sweep of the tail has probably given 

 rise to the idea that the porcupine can "shoot" 

 its quills when defending itself. 



Despite its defensive powers, however, the 

 porcupine is, on occasion, successfully attacked 

 by various enemies, including the mountain 

 lion, bobcat, fisher, and even the eagle and 

 great horned owl. The fisher is said habitually 

 to kill and feed upon them, and the encystecl 

 quills are commonly found under its skin. 



The frightful effect of an ill-judged attack 

 on a porcupine is shown by inexperienced dogs 



