MODE OF TRAPPING BEAVER. 225 



breaches must be made in these structures before they 

 abandon the work of their restoration ; and even after 

 deserting the place, either they or other beavers are 

 sure to return when circumstances become favorable. 

 The instances are rare in which they are seen, for 

 any length of time, while engaged upon this work. 

 Captain Daniel Wilson informed me that he had seen 

 beavers at work on the Grass Lake dam, making 

 ordinary repairs, on several different occasions, while 

 watching at night for deer, in one of the trees grow- 

 ing in its crest. They came down to the dam singly, 

 and swam along its line from one end to the other. 

 When any work seemed to be needed, each one, upon 

 his own motion and without any concert with others, 

 devoted himself to the task of setting it right. They 

 brought sticks in their mouths, and mud with their 

 paws held under the throat. When these were ar- 

 ranged and the mud deposited upon them, they gave 

 the latter a heavy stroke with the tail to pack it 

 firmly in its place. Four or five beavers came down 

 each night, at intervals of half an hour apart; each 

 and all of whom performed more or less work upon 

 the dam, and did it in the same manner. One night, 

 while I was watching upon the same dam, the first 

 beaver made his appearance about eleven o'clock, and 

 swam across the pond near the crest of the dam, com- 

 ing within a few feet of the place where I was par- 

 tially concealed. Having discovered the intrusion, he 

 went under immediately, giving the alarm signal with 

 his tail. After this he went behind the grass island 

 upon which the lodge represented in Plate XIII. is 

 situated, and repeated these signals at intervals for 

 more than an hour; thus preventing other beavers 



15 



