Alabama, 191 3. 65 



by 4 inches wide. The tail is never used as a trowel in building 

 dams, but only as a propeller in swimming. 



Dam-building is done in two ways. With his front feet the 

 animal digs up soft mud, holds the mass with his fore legs against 

 his breast, and swims with it to the dam. There he deposits it 

 where it is most needed, and pats it down with his front feet. To 

 strengthen the structure, he brings sticks four or five feet long, and 

 one or two inches in diameter, from which he has eaten the bark. 

 These he usually lays upon the dam crosswise or nearly so, and 

 fills between them with mud. 



When Beavers have to build a dam exceeding fifty feet in 

 length, to flood low ground, they usually lay it out with a curve 

 up-stream. The dam built by the Beavers in the New York Zoo- 

 logical Park is about fifty feet long, and three feet high, and quite 

 shapely curved up-stream. 



In most localities inhabited by the Beavers, the banks of the 

 streams are so low that the animals cannot burrow into them, 

 and consequently they build houses for themselves. The ordinary 

 Beaver house is a huge pile of neatly trimmed six-foot poles, with 

 all spaces between the sticks plastered with mud. The one in the 

 Zoological Park is about fifteen feet in diameter, and five feet 

 high, with a central chamber above high-water-mark, and its only 

 entrance is well under water. If a beaver house is attacked, the 

 occupants immediately seek refuge in deep water. 



The trees which furnish bark most prized by the Beaver as 

 food are the poplar, cottonwood, willow, birch, elm, box-elder and 

 aspen. The bark of the oak, hickory, or ash is not eaten. 



The Beaver's front teeth (incisors) are very strong and sharp, 

 and the muscles of the jaw are massive and powerful. It is no 

 uncommon thing for a Beaver to fell a tree a foot in diameter in 

 order to get at its branches. It is said by some observers that large 

 trees are made to fall as the Beavers prefer to have them, — toward 

 their pond. In felling a tree, they first remove the bark from a 

 circle a foot in width, just above the spur roots, standing on their 

 hind legs while they work. Then, with their huge, chisel-like 

 incisors they cut out chips, circling round the trunk all the while, 

 until only the heart of the trunk remains, and the tree falls. 



5 BB 



