152 AXIJJAL LlFIi JX THE YOSEMITE 



Occurrence. — Moderately common resident in boreal region on Sierra Nevada. Work- 

 ings noted from Porcupine Flat eastward to Tuolumne Meadows. Individuals occur 

 (rarely) on floor of Yosemite Valley and are reported at even lower stations. Lives 

 in coniferous trees, chiefly lodgepole pines. Solitary. 



The Yellow-haired Porcupine is perhaps one of the best known of our 

 native mammals, by reputation at lea.st, though not all the stories which 

 are current concerning it are accurate. Being of sluggish disposition and 

 active by day as well as night it gives visitors in the high Sierras many 

 opportunities to observe it at close range. And should these fail, the work 

 of the animal is evident in many places. 



In general, the porcupine is to be found in the high Sierras above the 

 level of Yosemite Valley; its range is practically the same as that of the 

 lodgepole pine. Occasionally, however, individuals are observed at much 

 lower levels. We were told, for example, of one trapped on the floor of 

 Yosemite Valley in September, between 1916 and 1918. We have been 

 told of individuals seen on Bullion Mountain. And at Snelling one resident 

 told of a porcupine which he had shot in the river bottom a mile from 

 town, and of two or three others, possibly castaways brought down the 

 river in drift, which had been observed in the same locality. 



tip of quill (is) base of quill ^3) 



Fig. 26. Quill from Yellow -haired Porcupine showing details of tip and base. At 

 the tip are numerous small barbs which \Yhen the quill penetrates skin or flesh keep it 

 from being pulled out ; at the base is the slender and weak connection which makes for 

 ready separation of the quill from the skin of the Porcupine. 



The porcupine's chief claim to attention lies in its covering of sharp- 

 pointed hollow quills which are especially developed on its back and tail. 

 These quills are specialized or modified growths which supplant some of 

 the underfur normally present on a mammal's body. (See fig. 26.) Indi- 

 vidually, a quill consists of a hollow tube, closed at both ends, about \\<\ 

 to Vs iiich in diameter and 1 to 3 inches in length. The tip is supplied 

 with a great number of backward-projecting small barbs which upon touch- 

 ing the flesh of another animal iruitantly engage and hold fast. The bases 

 of the quills are constricted and are weakly held in the porcupine's skin so 

 that they become detached readily when the barbs are imbedded in some 

 victim. 



When a i)()r('upine expects attack from another animal it draws its 

 head down, and erects the quills of its back; if the enemy approaches 

 too closely, it also sweeps the tail quickly to one side or the other. This 

 is sufTicient warning for most animals, but certain species, and particularly 



