Many a time I have seen a beaver come out of the doorway of his house and go swimming toward the food-pile with his hands against his breast. At the pile, if there was nothing small or short enough, he set to work and gnawed it off. The piece secured was taken into the doorway either in his hands or in his teeth. Afterward a beaver--the same one, I suppose--came out of the doorway, and cast the clean bone of the stick, from which the bark had been eaten, into the bottom of the pond.
When there is nothing else to do, the beaver apparently comes into the pond a few times each day for a swim. In the midst of swimming he rises at times to the under surface of the ice and, with his nose against it, exhales a quantity of air. After remaining with nose at this point a few seconds, the action of the air bubbles indicates that he is inhaling the purified air.
The rootstocks of the water-lily are sometimes dug from the bottom of the pond. At other times the beaver eats the stalks of plants that grow in the water, or digs out willow or other roots around the edge of the pond. Numbers of trout frequently lie in the water close to the doorway of a beaver house or around the food-pile. Possibly the beaver dispense tidbits of food that are liked by the trout. Occasionally grubs fall from the holes in wood from which beaver have eaten the bark. While beaver are digging in the bottom of the pond they doubtless unearth food-scraps that are welcome to trout, for these often hover in numbers on the outskirts of the muddy water which beaver roil while digging.
Although it appears that beaver have dull winters with but little to do but eat, sleep, and swim, it is probable that some of their time is spent at work. A part of their tunneling and pond-bottom canal-digging is done in winter. I have known of their extending canals in the bottom of the pond and making submarine tunnels while the pond was ice-covered.
There are times when the dam has sprung a leak and must be repaired on the inside beneath the ice. Early thaws and spring freshets sometimes wreck a dam beyond repair, or do extensive damage to the house or dam at the time when beaver enemies are likely to be at their leanest. The house and dam are sometimes ruined when the streams are so low and icy that it is not safe for beaver to go about. I know of two colonies that were crushed out of existence by snow-slides.