(preface 



within fifteen minutes. Studies were carried on in 

 these near-by colonies in spring, summer, autumn, 

 and winter. 



One autumn my entire time was spent in mak- 

 ing observations and watching the activities of 

 beaver in fourteen colonies. Sixty-four days in 

 succession I visited these colonies, three of them 

 twice daily. These daily investigations enabled 

 me to see the preparations for winter from begin- 

 ning to end. They also enabled me to understand 

 details which with infrequent visits I could not 

 have even discovered. During this autumn I saw 

 two houses built and a number of old ones repaired 

 and plastered. I also saw the digging of one 

 canal, the repairing of a number of old dams, and 

 the building of two new ones. In three of these 

 colonies I tallied each day the additional number 

 of trees cut for harvest. I saw many trees felled, 

 and noted the manner in which they were moved 

 by land and floated by water. 



The greater number of the papers in this book 

 were written especially for it. Parts of the others 

 have been used in my books Wild Life on the 

 Rockies and The Spell of the Rockies. " The Bea- 



viii 



