Yellowstone Beaver 203 



in color. There are four teeth in the molar series on either side of 

 each jaw, formed on much the same principle as the incisors, of ver- 

 tical layers of enamel and dentine, the unequal wear of which gives 

 a good grinding surface. 



Food of the Beaver 



The food of the beaver consists largely of the bark of deciduous 

 trees, of which, in the Yellowstone and other parts of the west, 

 aspen is the favorite. Willows and alders are also used, but not the 

 bark of conifers, except occasionally. In summer other plants are 

 also used ; and I have noticed that they seemed especially fond of 

 wild rose bushes. The beavers would go up on the hillside, near the 

 Cooke City road, at Camp Roosevelt, and gather great bunches of 

 these, holding them in their mouths and trailing them along down 

 to the water. They sometimes ate them there by the bank, and some- 

 times they would swim with them to the lodge, diving and carrying 

 them inside. Cow parsnip, choke cherry and various others of the 

 plants growing along the shores of the ponds were also eaten. At 

 Crescent Hill, near Yanceys, we saw beaver trails leading through 

 the grass to where many thistles had been nipped off close to the 

 ground. I saw grass carried to the lodge on several occasions, but 

 there is a possibility that it might have been used for bedding. 



One often sees in popular articles the statement that a beaver cuts 

 a tree so as to make it fall in any desired direction. This is not 

 true, as the animal makes the cut where most convenient to himself, 

 and lets the tree fall as it may. On a steep hillside, and with trees 

 up to six inches in diameter, in a great majority of cases the cut will 

 be made on the uphill side, or on one side or the other, rarely on the 

 downhill side, and all the cutting will be done from one side. From 

 the way the cuts are made, one might suppose the trees would fall 

 uphill, or to one side, but nearly all of them fall downhill, because 

 they naturally lean that way. 



When the trees are growing on level ground it is a different 

 matter. They are usually cut quite evenly all round, especially if 

 the tree is a large one. This is well illustrated in the case of the 

 cottonwood in figure 50. A beaver may start to cut a tree, and then 

 stop work, returning some time later to finish the job. This was 

 finely illustrated in the case of a large aspen on the North Fork of 

 Elk Creek, beyond Yanceys (figure 51). This was first seen July 

 20, and then had a considerable notch in it, not very freshly cut, but 



