The Rodents, or Gnawing Animals 155 



parts of the bank where their holes are; these also become filled up, because the beavers carry 

 into them every day fresh quantities of wood-chips to make their beds. The beavers then 

 scrape out the earth on the top, pile sticks over this, plaster the sticks with mud, and so build 

 a dome over their bedroom. In time this is raised higher and higher, the artificial lake rises 

 too, and the complete "beaver-lodge" surrounded with water is seen. The old trappers who 

 found these in situ imagined they were built at once and outright in the water. The 

 experiments and observations at Leonardslee, in Sussex, where Sir E. G. Loder has kept 

 beavers in a stream for ten years, show that the "evolution" of the lodge is gradual and only 

 incidental. But the building of the dyke, the cutting of the trees, and the making of the 

 pool are done with a purpose and definite aim. 



What this is, and how done, is explained in the following description of the beaver 

 colony at Leonardslee: "Their first object was to form in the brook a pool, with water 

 maintained at a constant height, to keep the mouth of their burrow in the bank submerged 

 during the droughts of summer. To this end they built a dam, as good a specimen of 

 their work as can be seen 

 even in Canada. Its situa- 

 tion was carefully chosen. 

 A small oak, growing on 

 what appears to have been 

 a projection in the bank, 

 gives support to the work. 

 It may be concluded that 

 this was part of their 

 intention ; for though they 

 have cut down every other 

 tree in their enclosure to 

 which they had access, 

 except two or three very 

 large ones, they have left 

 this small tree which 

 supports the dam un- 

 touched. (Later, when 

 the dyke was stronger, 

 they cut it down.) Above 

 this stretches the dam, 

 some 12 yards wide, and 

 rising 5| feet from the 



base to the crest. The beavers built it solidly of battens of alder, willow, larch, and other 

 straight-limbed trees, cut into lengths of from 2 to 3 feet. The bark of each was carefully 

 gnawed off for food ; and the whole work, constructed of these cut and peeled logs, has a 

 very regular and artificial appearance. Smaller twigs and sticks are jammed in between the 

 battens, and the interstices are stuffed with mud, which the beavers bring up from the 

 bottom of the pool in their mouths, and push in with their feet, making the whole structure 

 as watertight as a wall." This dam converted what was a narrow brook into a long lake, some 

 50 yards by 15 or 20 yards broad. Later the beavers made another larger dam below this, 

 cutting down some more trees. One tree gave them a great deal of trouble ; it was a beech, 

 40 feet high, and hard to gnaw; so they waited till the water rose round it, and then dug 

 it up. When the large dam was made, quite a considerable lake was formed below the 

 first. They then neglected their first dam, and let the water run out of the top lake into 

 the lower one. At the time of writing there are five old beavers and a family of young ones 

 at Leonardslee. The work -done by these beavers, so few in numbers, shows how large colonies 

 may alter the course of rivers. 



Photo by W, P. Dando\ 



GAMBIAN POUCHED RAT. 

 These rats are able to carry food in their cheek-pouches, which are used as pockets. 



[Regent's Part:. 



