1936] MAMMALS OF OREGON 229 



oval, denticulate soles, and heavy, curved claws; ears small and hidden in 

 the fur; eyes small; nose soft and furry. Pelage in winter a dense coat of 

 long, soft, blackish fur, thickly set over upper parts with stout, sharp, and 

 terribly barbed quills from 1 to 4 inches long, partly concealed over back and 

 sides by a loose outer coat of coarse, erectile yellow or yellow-tipped hairs 6 

 to 10 inches long; lower parts covered with fur and coarse hair, and lower 

 surface of tail with rigid bristles that help it to serve as a prop in climbing-. 

 Summer pelage with but little fur, mainly naked quills and long outer hairs, 

 the black-tipped white quills fully exposed when erected. Young, black all over. 

 Measurements. Adult male : Total length, 765 mm ; tail, 211 ; foot, 105 ; ear 

 (dry), about 20. Weight of large males generally estimated at 20 to 30 pounds. 

 One taken in Yellowstone Park, Wyo., weighed 33V 2 pounds. Weight of 7 

 males from Oregon, excluding young of the year, given by Gabrielson as 18 

 to 22,1/2 pounds ; of 8 females, as 12 to 14 pounds. This series evidently included 

 no very old animals. 



Distribution and habitat. The yellow-haired porcupine occurs 

 over most of the western United States from the edge of the Great 

 Plains to the Pacific, but the areas where it grades into the more 

 northern and southern forms have not been fully determined. In 

 Oregon it covers almost the whole State from desert valleys to the 

 coast and from the hottest upper Sonoran Valleys to timber line 

 on the mountains, seemingly with no regard to well-established life 

 zones. It is much less common in the humid coast region, however, 

 than in the dry interior of the State, and the writer has seen no 

 specimens from west of the Cascades. 



General habits. Porcupines are slow, rather stupid, timid ani- 

 mals, depending mainly on their spiny armor for protection, but 

 always eager to get under cover or up a tree, or into a cave or cleft 

 in the rocks for additional safety. Their only method of defense 

 is to present the back with erect spines (pi. 37) to the enemy and to 

 strike upward and sideways with the powerful, spiny tail, but in 

 most cases this is ample defense. The quills are not thrown, as is 

 commonly believed, but may be driven deep into an enemy by a 

 blow of the tail, and if only lightly imbedded will work their way 

 by means of their barbed points in through skin and flesh. 



These animals are slow but industrious travelers, often leaving 

 their lines of oval tracks in dusty trails for miles in a single night, 

 wandering at random over deserts or open valley country, finding 

 an abundance of plant food wherever they are, and taking advantage 

 of any available cover for places to sleep during the day. 



They have squeaky, querulous voices, with many modifications 

 to express anger, fear, or pain, and softer little squeaks and grunts 

 for friendly feelings or entreaty. A treetop song has been re- 

 ported in the mating season, but this needs further study. Gen- 

 erally, however, they are silent and by many are supposed to be 

 voiceless. 



They are excellent climbers and spend much of their time among 

 the branches of large trees (pi. 38), where they are comparatively 

 safe and where much of their winter food is obtained. They do not 

 hibernate even in the coldest winter weather and the deeper the 

 snow the more easily available becomes their food of twigs and 

 bark. 



Breeding habits. The females have four mammae in a large rectan- 

 gle on the abdomen, but often only the anterior pair is developed. The 

 young are sometimes 2, but more commonly only 1, born usually in 



