So far are the beaver from driving stakes into the ground when building their houses, that they lay most of the wood crosswise, and nearly horizontal, and without any other order than that of leaving a hollow or cavity in the middle; when any unnecessary branches project inward, they cut them off with their teeth, and throw them in among the rest, to prevent the mud from falling through the roof. It is a mistaken notion, that the wood-work is first completed and then plaistered; for the whole of their houses, as well as their dams, are from the foundation one mass of wood and mud, mixed with stones, if they can be procured. The mud is always taken from the edge of the bank, or the bottom of the creek or pond, near the door of the house; and though their fore-paws are so small, yet it is held close up between them, under their throat, { 234} that they carry both mud and stones; while they always drag the wood with their teeth.
All their work is executed in the night; and they are so expeditious in completing it, that in the course of one night I have known them to have collected as much mud at their houses as to have amounted to some thousands of their little handfuls; and when any mixture of grass or straw has appeared in it, it has been, most assuredly, mere chance, owing to the nature of the ground from which they had taken it. As to their designedly making a composition for that purpose, it is entirely void of truth.
It is a great piece of policy in those animals, to cover, or plaister, as it is usually called, the outside of their houses every fall with fresh mud, and as late as possible in the Autumn, even when the frost becomes pretty severe; as by this means it soon freezes as hard as a stone, and prevents their common enemy, the quiquehatch, from disturbing them during the Winter. And as they are frequently seen to walk over their work, and sometimes to give a flap with their tail, particularly when plunging into the water, this has, without doubt, given rise to the vulgar opinion that they use their tails as a trowel, with which they plaister their houses; whereas that flapping of the tail is no more than a custom, which they always preserve, even when they become tame and domestic, and more particularly so when they are startled.