548 



Life-histories of Northern Animals 



The ordinary house has but one chamber, but I have 

 seen examples with more, doubtless the product of two families 

 uniting their efforts, although each family lives by itself, having 

 separate rooms and doorways. In September, 1904, I ex- 

 amined a large rat-house on Lake Winnipegosis, and made 

 the accompanying diagrams. (Fig. 158.) 



RAFTS This house was probably the joint home of two families. 



Each of these large houses is surrounded by a number of 

 rat-rafts which are like outlying fortresses of the great central 



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^"/'7i'.(^%^.' < 



Fig. 158 — A large rat-house sketched at Lake Winnipegosis in Sept., 1904. As seen from above, and in plan, 



camp; these are merely floating bunches of reeds, with anchor- 

 age of a few growing reeds. Their first purpose seems to be 

 furnishing the members with landing places where they can 

 feed comfortably; but when the ice forms they answer a new 

 need — they afford breathing places; for the reed raft makes 

 it easy to keep the ice open there, and also conceals the Musk- 

 rat that is using the place. 



In the winter, if the occupants be frightened out of the big 

 citadel, they will usually be found in a few minutes scattered 

 at the various breathing raft-holes. 



In very deep water we find a type of nest that is both house 

 and raft. Its foundation instead of being a mud island is a float- 

 ing mass of reeds. It answers well for the fall and winter, but 

 usually becomes water-logged and sinks from sight in the spring. 



