THE RODENTS, OR GNAWING ANIMALS 155 



come 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 build a dam, as good a specimen of their work 

 as can be seen even in Canada. Its situation 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 con- 

 cluded 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 untouched. 

 (Later, when the dyke was 

 stronger, they cut it down.) 

 Above this stretches the 

 dam, some 1 2 yards wide, 

 and rising 5^ feet from 

 the base to the crest. The 

 beavers build 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 water-tight 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. 



Phttt kj W. P. Dando 



GAMBIAN POUCHED RAT 



Thett ran art obit to carry food in their check-pouches, which are uted at pocketi 



