Every beaver pond is a settling-basin that takes sediment and soil from the water that passes through it. If this soil were carried down it would not only be lost, but it would clog the deep waterway, the river channel. Deposited in the pond, it will in time become productive. During past ages the millions of beaver dams in the United States have spread soil over thousands of square miles and rendered them productive. Beavers prepared the way for numerous forests and meadows, for countless orchards and peaceful, productive valleys.
The Moraine colonists gathered an unusually large harvest during the autumn of 1909. Seven hundred and thirty-two sapling aspens and several hundred willows were massed in the main pond by the largest house. This pile, which was mostly below the water-line, was three feet deep and one hundred and twenty-four feet in circumference. Would a new house be built this fall? This unusually large harvest plainly told that either children or immigrants had increased the population of the colony. Of course, a hard winter may also have been expected.
No; they were not to build a new house, but the old house by the harvest pile was to be enlarged. One day, just as the evening shadow of Long's Peak had covered the pond, I peeped over a log on top of the dam to watch the work. The house was only forty feet distant. Not a ripple stirred among the inverted peaks and pines in the clear, shadow-enameled pond. A lone beaver rose quietly in the scene from the water near the house. Swimming noiselessly, he made a circuit of the pond. Then for a time, and without any apparent purpose, he swam back and forth over a short, straight course; he moved leisurely, and occasionally made a shallow, quiet dive. He did not appear to be watching anything in particular or to have anything special on his mind. Yet his eyes may have been scouting for enemies and his mind may have been full of house plans. Finally he dived deeply, and the next I saw of him he was climbing up the side of the house addition with a pawful of mud.
By this time a number of beavers were swimming in the pond after the manner of the first one. Presently all began to work. The addition already stood more than two feet above the water-line. The top of this was crescent-shaped and was about seven feet long and half as wide. It was made mostly of mud, which was plentifully reinforced with willow cuttings and aspen sticks. For a time all the workers busied themselves in carrying mud and roots from the bottom of the pond and placing these on the slowly rising addition. Eleven were working at one time. By and by three swam ashore, each in a different direction and each a few seconds apart. After a minute or two they returned from the shore, each carrying or trailing a long willow. These were dragged to the top of the addition, laid down, and trampled in the mud. Meantime the mud-carriers kept steadily at their work; again willows were brought, but this time four beavers went, and, as before, each was independent of the others. I did not see how this work could go on without some one bossing the thing, but I failed to detect any beaver acting as overseer. While there was general coöperation, each acted independently most of the time and sometimes was apparently oblivious of the others. These beavers simply worked,—slowly, silently, and steadily; and they were still working away methodically and with dignified deliberation when darkness hid them.
Most beaver houses are conical and round of outline. This house originally was slightly elliptical and measured forty-one feet in circumference. After enlargement it was almost a flattened ellipse and measured sixty-three feet in circumference. Generally I have found that small beaver houses are round and large ones elliptical.
One of the last large interesting works of the Moraine Colony was the making of a new pond. This was made alongside the main pond and about fifty feet distant from it. A low ridge separated the two. As it was nearly one hundred feet from the stream, a ditch or canal was dug from the stream, below the main pond, to fill it. The new pond was made for the purpose of reaching with a waterway an aspen grove on its farther shore.
The making of the dam showed more forethought than the getting of the water into the pond. With the exception of aspen, no dam-making material such as beavers commonly use was to be found. The population of the colony was now large, while aspen, the chief food-supply, was becoming scarce. Would the beavers see far enough ahead to realize this? Evidently they did; at any rate not a single precious aspen was used in making the dam. Close to the dam-site was a supply of young lodge-pole pines; but it is against the tradition of the beaver to cut green pines or spruces. Two of these lodge-poles were cut, but evidently these pitchy, smelly things were not to the beavers' taste and no more of them were used.
Not far away were scores of fire-killed trees, both standing and fallen. "Surely," I said to myself, when two dead chunks had been dragged into place, "they are not going to use this dead timber?" A beaver avoids gnawing dead wood; it is slow work, and besides is very hard on the teeth. Most of these dead trees were inconveniently large, and were fire-hardened and full of sand-filled weather-cracks; but contrary to all my years of observation, they, after long, hard labor, built an excellent dam from this material.
I have determined to do all I can to perpetuate the beaver, and I wish I could interest every man, woman, boy, and girl in the land to help in this. Beaver works are so picturesque and so useful to man that I trust this persistent practicer of conservation will not perish from the hills and mountains of our land. His growing scarcity is awakening some interest in him, and I hope and half believe that before many years every brook that is born on a great watershed will, as it goes swiftly, merrily singing down the slopes toward the sea, pass through and be steadied in a poetic pond that is made and will be maintained by our patient, persistent, faithful friend the beaver.