J.R.Alcorn 1940 Castor canadensis Yellowstone River,5 mi.W Forsyth,2750 ft,Rosebud Co., Montana. June 4, 1940. I was standing on the bank of a small branch of the river when I looked downstream and saw a Beaver swimming toward me. I sat down and the animal approached to within 30 ft. of me then dove and re-appeared about 50 ft. upstream. It swam close to the bank and much of the time it was almost out of sight because of the overhanging willows. When about 150 ft. away I stood up and the animal gave a number of "splashes" which made a noise like someone throwing a 10 lb. rock into the water. This noise was apparently made by slapping the water with the tail. June 5, 1940. In this same general vicinity today I saw a number of Cottonwood trees that had apparently been "fallen" by beavers. Some of these trees were 14 inches in diameter. As I walked up the river (N bank) I could see many beaver tracks in the mud and one beaver house was built in the edge of the water. I noted that both