82 



OKDERS OF MAMMALS— GXAWIXG ANIMALS 



It is seldom that anyone sees a live Beaver in its 

 haunts during the middle of tlie day, but it is 

 possible to do so during the hour before sunset. 

 In pubUc zoological gardens and parks, the per- 

 sistence and success of this animal in a^-oiding 

 observation is very disappointing to visitors, 

 and exasperating to directors and keepers. 



This is the largest gnawing animal in North 

 America. ■ A huge specimen caught in Maine, 

 in 1900, weighed a trifle over .50 pounds. A 

 large one in the New York Zoological Park is 31 

 inche.s long, has a tail 12 inches long and weighs 

 44 pounds. 



The American Beaver is still found in a few 

 localities, — but in very small numbers, — from 

 the Rio Grande in Texas throughout the Rocky 

 Mountains, Sierra Nevada and Cascade Moun- 

 tain regions northward to the limit of trees, and 

 southeastward through Canada to northern New 

 England. The number now remaining in Col- 

 orado has been estimated at one thousand. 



The Beaver's efforts are directed toward its 

 own preservation and comfort. It builds ex- 

 tensive dams of mud, grass and sticks, in order 

 to create ponds in which it can hide from its 

 enemies, maintain a safe refuge close by the wood 

 on which it feeds, and have an under-water door- 

 way to its house or burrow. More than this 

 the pond .serves as a refrigerator, in the bottom 

 of which the animal stores its supplies of food- 

 wood for winter use, when the surface is frozen 

 for a long period. 



Sometimes when food-wood on a beaver pond 

 becomes scarce, the animals dig canals into 

 places where fresh supplies can be cut, and 

 floated down to the pond. These canals are 

 usually about two feet wide. 



A Beaver is readily recognized by its very flat, 

 hairless and scaly tail, which beyond the hair 

 of the body is about 9 inches long by 4 inches 

 wide. The tail Ls 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 exceed- 

 ing 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 forty feet long, and three 

 feet high, and quite sharply curved up-stream. 



In most localities inhabited by Beavers, the 

 banks of the streams are so low that the animals 

 cannot burrow into them, and consequently 

 they build houses for themselves. Tlie ordinary 

 Beaver house is a huge pile of neatly trimmed 

 six-foot poles, with all spaces between the sticks 

 plastered full of 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 occu- 

 pants immediately .seek refuge in deep water. 



SKULL OF BEAVER, .V TYriC.VL RODENT. 



The trees which f\n-nLsh bark most prized by 

 the Beaver as food are the poplar, cottonwood, 

 wiUow, 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 Bea'\'er 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 



