In Beaver World

by Enos A. Mills

A clean fox track led from the woods in a straight line across the snowy surface of the pond to the house, which stood near the centre of this smooth white opening. The tracks encircled the house and ascended to the top of it, where the record imprinted in the snow told that here he watchfully rested. Descending, he had sniffed at the bushy tips of the winter food-pile that thrust up through the ice, then crossed the dam to plunge into the snowy tangle of willows.

Water was still pouring and gurgling down a steep beaver slide. This was ice-and-snow-covered except at two points where the swift splashing water dashed intermittently from a deep icy vent. While I was examining the beauty of the upbuilding icy buttresses by one of the vents, a water-ouzel came forth and alighted almost within reach. I stood still. After giving a few of his nodding bows, he reëntered the vent. Presently he emerged from the lower vent and, alighting upon an ice-coated boulder, indifferent to the gray sky from which scattered flakes were slowly falling and despite a temperature of five below zero, he sang low and sweetly for several seconds.

Beaver do not surrender themselves to the confines of a house and pond until cold solidly covers the pond with a roof of ice. The time of this is commonly about the first of December, but the date is of course, in a measure, dependent upon latitude, altitude, and the peculiar weather conditions of each year. Most beaver return to the old colony, or start a new one by the first of September. They have had a merry rambling summer and energetically take hold to have the house and dam ready and a harvest stored by the time winter begins.

But they are not always ready. Enemies may harass them, low water delay them, or an unusually early winter or even a heavy snow may so hamper them that, despite greatest effort, the ice puts a time lock upon the pond and closes them in for the winter without sufficient supplies.

Early one October an early snowfall worked hardship in several colonies near my home. Fortunately the ponds were not deeply frozen, and those colonies which had aspen groves close to the water succeeded in felling and dragging in sufficient food-supplies for the winter. As snow drifted into the groves, many of the trees harvested were cut from the tops of snowdrifts, and thus left high stumps. The following summer a number of these stood four feet above the earth and presented a striking appearance alongside the sixteen-inch stumps of normal height.

One of these storm-caught colonies fared badly. The inhabitants were obliged to go a long distance from the water for trees, and their all too scanty harvest was gathered with some loss of life. Apparently both wolves and lions discovered the unfortunate predicament of the harvesters, and lay in wait to catch them as they floundered slowly through the snow. The following winter these colonists tunneled through the bottom—perhaps the least frozen part of the dam—and came forth for food long before the break-up of the ice. The water drained from the pond, and after the ice had melted, the bottom of the pond revealed a torn-up condition as though the starving winter inmates had dug out for food every root and rootstock to be found in the bottom.

While visiting ponds at the beginning of winter, I have many times noticed that, shortly after the pond was solidly frozen over, a hole was made through the dam just below the water-surface of the pond. This lowered the water-level two inches or more. Did this slight lowering of the water have to do with the ventilation of the ice-covered pond, or was it to put a check on deep freezing, or for both purposes?

In the majority of cases these holes were made from ponds which, during the winter, received but a meagre inflow of fresh water. Naturally, ponds receiving a strong inflow of water would be better ventilated, and would freeze less swiftly and deeply than those whose waters became stagnant. This drawing-off of water after a few inches of ice had formed, would, in some places, despite the settling of the ice, form an air blanket that would delay freezing, and thus possibly prevent the ice from forming so thickly. The air admitted by drawing off the water would be inclosed beneath the ice, and might thus be helpful to the beaver inclosed in house and pond. In only a few cases were these holes made from ponds which had subway tunnels,—tunnels which run from alongside the house through the bottom of the pond to a point above water-level on the shore. In a few instances the beaver, I do not know how many, came out of this hole, cut and ate a few twigs, and then returned and closed it. Twice this was used as a way out by beaver who emerged and went to other colonies. In one case the beaver entered the other pond by making a hole through the dam. In the other they entered the pond through a subway tunnel. While these holes which lower the pond-level may have chiefly to do with ventilation, or may be for the purpose of putting a check on freezing, my evidence is not ample enough for final conclusions.

A sentence of close confinement for about a third of the year for an animal that breathes air and uses pure water, is simply one of the strange ways that work out with nature. While winter lasts, a beaver must spend his time either in the dark, ill-ventilated house or in the water of the pond. Apparently he does much sleeping and possibly has a dull time of it. No news, no visitors, and apparently nothing to do! Still a beaver has food, and when dangers surround the wild folk outside the pond’s roof of glass, he would be considered a good risk for life insurance.

Although the pond is commonly covered with snow, or the ice curtained with air bubbles, there have been numerous times during which I have had clear views into the water, and could see and enjoy all that was going on within, as completely as though looking at fish or turtles through the glass walls of an aquarium. Often I have peered through the ice which covered the most used place of a winter beaver pond,—the area between the house-entrance and the food-pile. The thinness of the ice over this place was maintained by spring-water which came up through the bottom, and the beaver had so arranged their affairs that they made the best use of this shallow-freezing water. Of course most ponds are without springs.