Notes on the Habits of the Beaver. 
329 
The following Communications were then read : — 
1. Notes on the Habits of the Beaver. By an Eye-witness, James 
M'Kenzie, Esq. , an Officer in the Hudson's Bay Company Service. 
Communicated by Andrew Murray, Esq. 
The Beaver is found over a wide extent of country on the American 
continent, extending east and west from the Atlantic to the Pacific, and 
probably from Lat. 48° to 54° north ; but on the slopes of the Rocky Moun- 
tains, where the climate is comparatively mild, he is met with much 
further north and south. My object, however, is not so m.uch to define 
his geographical limits, as to make a few notes on his habits. Beavers 
build occasionally on the shores of lakes, but prefer the banks of rivers and 
streams. They go generally in pairs ; and having selected a convenient 
site near the banks of the river, the two clear a circular piece of ground, 
generally 6 feet in diameter, carefully removing everything on the sur- 
face. This done, they carry in their arms, walking on the hind feet, 5 
to 10 lbs. of strong clay from the river, and deposit it to a width of 2 feet 
all round the circle, thus making the diameter 4 feet ; then collecting long 
grass orbranchesof willow, theymix upthe whole well together, so as to form 
a good foundation. In this way they build the walls to a height of about 
10 feet, gradually narrowing ; and the whole has a rounded form, some- 
what like an oven. Unless they had some means of plastering or smooth- 
ing down the mud walls, the rain would certainly wear them away in a 
short time ; and although it is supposed that the beaver never uses his 
tail as a trowel, I have it from the authority of eye-witnesses that he does 
so — in fact, Nature has furnished the animal with the tool ready made to 
his hand. After he has laid the foundation, and, indeed, in process of lay- 
ing it, before the clay gets dry, he uses the trowel ; and when the wall is 
raised to a certain height, he goes round the circle, carefully plastering 
every load he carries from the river and lays on his house. The lodge 
has neither doors nor windows, and the finishing hand is not put to it till 
he is far advanced with his bridge, or perhaps until he has completed it. 
Before the house can be completed, a subterranean passage is excavated 
from its centre to the dam or pond, and this at a depth varying from 2 to 
6 feet, depending on the ditference of level between the river and house. 
He then strews his floor with thin strips of willow tree, cut by him in the 
form of carpenter's shavings, for his winter's bed. The construction of 
the bridge shows even more ingenuity than the construction of the house, 
and is of various lengths, depending on the size of the stream. AVlien 
only a few feet wide, the wall goes straight from bank to bank at right 
angles to the current ; when larger, or about 40 feet wide, it is formed of 
a single curve ; but when the river to be bridged is from 100 to 120 feet 
wide, the wall is formed into a series of curves, or undulations as it were. 
He understands pretty well the properties of straight and curved lines in 
his engineering works, and knows the mode best suited to the circum- 
stances in which he is placed. If his domicile is situated on a wide stream, 
he adopts that mode of construction which is best adapted to withstand 
the pressure of a great body of water and ice on the opening of the navi.; a- 
tion in the spring. The wall is about 12 feet high and 9 feet wide at 
bottom, but on the side exposed to the current it slopes w:th the stream, 
forming, perhaps, an angle of about 40°. At any rate, wliile the wall is 
about 9 feet wide at bottom, it is only 1 foot wide at top. He selects 
for the foundation pieces or logs of timber which are water-soaked ; but 
if he cannot find enough of these, any wood, either green or dry, will do, 
covering them with large stones, to prevent their rising to the surface. 
But logs thus placed on one another across a stream could not be so well 
