Drought in Beaver World
Not until one year of drought did I realize how dependent the beaver is upon a constant water-supply that is both fresh and ample. A number of beaver colonies close to my cabin were badly afflicted by this dry period. I was already making special studies of beaver ways among the forty-odd beaver colonies that were within a few miles of my mountain home, and toward the close of this droughty summer I made frequent rounds among the beaver. By the middle of September I confined these attentions to five of the colonies that were most affected by low water. Two were close to each other, but upon separate brooks. The other three were upon one tumbling streamlet.
Autumn is the busiest time of the year in beaver world. Harvest is then gathered, the dam is repaired, sometimes the pond is partly dredged, and the house is made ready for winter,—all before the pond freezes over. But drought had so afflicted these colonies that in only one had any of the harvest been gathered. This one I called the Cascade Colony. It was the uppermost of the three that were dependent upon this one stream. Among the five colonies that I observed that autumn, this one had the most desperate and tragic experience.
Toward the close of September the colonists in each of the five colonies gave most of their attention to the condition of their dam. Every leak was stopped, and its water face was given a thick covering of mud, most of which was dredged from the bottom of the pond.
The beaver is intimately associated with water. He is not a landsman, and only necessity will cause him to go far from the water. The water in a main beaver pond is usually three or more feet deep, a depth needed all the year around. Where nature has provided a place of this kind that is close to his food-supply, the beaver uses it; he will not trouble to build a dam and form a pond of deep water unless this is necessary. But deep water he must have; to him it is a daily necessity in getting a living, moving about the easiest way, and protecting his life.
Early in October the first colony below the Cascade had to leave the old home because of the scarcity of water. There were seven or eight of them, and all went down-stream and joined another colony. From what I know of the two colonies I judge that this was probably a case of the old folks being forced to take refuge with their fortunate children. Apparently they were welcome.
A few days later the lowest of the three colonies on the Cascade streamlet was also abandoned. Two days before leaving home the beaver had commenced to harvest aspen for winter food. A few aspens were standing partly cut; a number untrimmed were lying where they fell; several had been dragged into the pond. But suddenly the beaver deserted the place.
The fifteen or sixteen in this colony went down-stream and took possession of an old and abandoned house and pond. They hastily repaired the dam and the house, and they had only just begun to gather supplies for the winter when the pond froze over. In the bottom of the pond, below the ice, there may have been an abundance of the tuberous growths of the pond-lily or a supply of intruding willow roots; both of these the beaver often dig out even while the pond is frozen over. These beaver in this old pond may have pieced out their scanty food-supply with these roots and endured until springtime; but I fear that at best they had a close squeak.
One brook went dry and the beaver folk on it moved up-stream. They left the dam well repaired, a new house, and a pile of green aspen cuttings in the pond. They were ready for winter when the water-failure forced them to find a new home. They scooped out a small basin by a spring in the top of a moraine, used the material for a dam, and into the pond thus formed dragged a few aspens and willows. A winter den was dug in the bank.