We humans can easily control the direction a tree falls by making a number of strategic cuts, essentially creating a hinge:

enter image description here

This prevents trees from falling on equipment and people and sets them up in a good location for the subsequent processing steps. I'm curious if beavers also perform directional felling and, if they do, how do they choose the direction (eg to fell the tree towards the damn, in a river, away from thick brush, etc)?

enter image description here

In this picture (and others), it appears as though the beaver has created a hinge. Is their any method to their technique or do they just start chewing and hope for the best?

  • 2
    $\begingroup$ As far as I know, beavers do not control this process. $\endgroup$
    – Chris
    Commented Jul 9, 2015 at 18:08

1 Answer 1


It is difficult to find a scientific answer to this question, but let me insert this citation from a specialist site:

Contrary to popular belief, beaver cannot plan the direction in which trees will fall. Many trees become hung up in the branches of surrounding trees and are lost to the colony. In heavily forested areas, this loss may amount to one-half of the trees felled.

Another source says the same.

But scientists think beavers may actually plan the direction of falling:

By measuring the falling angle of 888 trees of a variety of sizes cut near 8 different dams in southwestern Saskatchewan, we tested the hypothesis that beavers (Castor canadensis) fell trees in a non-random direction. We predicted that trees would be preferentially felled towards the dam to minimize the costs of transporting materials to the dam and to minimize the amount of time beavers spend on land. We established a 150 m wide × 250 m long transect at each dam and determined the felling angle of at least 100 aspen trees cut in each transect. We found that trees were felled by beavers with a mean felling angle of 357.9°, a direction not significantly different from that of the dam. In all, 62% of trees were felled within 45° of the direction of the dam. While our data are consistent with the hypothesis, an experimental test is required to establish the reason(s) for the pattern we found.

Their picture is better than thousands of words:

enter image description here

And another paper:

We studied patterns in the orientation of cutting when beavers (Castor canadensis) cut trees around Alum Creek Lake in central Ohio. For 462 trees, we measured the slope at the base of the tree, the orientation of the cut relative to this slope, the distance of the tree from the water, the radius of the tree, and the symmetry of the cut. The land around Alum Creek Lake generally slopes toward the water, so to direct the fall of a tree towards the water a beaver should cut a symmetrical tree from the downhill side. Cutting from the downhill side occurred for trees >9.0 m from the water. Near the shore, trees tended to lean toward the water and would fall toward the water regardless of the side from which the beaver cut. At distances <9-0 m from shore, beavers cut predominantly from the uphill side where it should be easy to sit and there is little danger of the tree falling on them. At all distances, beavers showed random orientation when cutting trees on shallow slopes (<20°), whereas on steep slopes (especially slopes >30°) they cut predominantly from the uphill side. Beavers cut small trees (<5.0 cm diameter) mostly from the downhill side, but tended to cut trees >5.0 cm in diameter from the uphill side. Overall, enough factors interacted that no single pattern of cutting existed for all trees.

  • 4
    $\begingroup$ @Remi.b this sentence relates to your point - that the actual studies are scarce. Of course, if we have some budget and grants we can check any theory we want $) $\endgroup$
    – Ilan
    Commented Jul 9, 2015 at 20:31
  • 1
    $\begingroup$ Thanks for the answer. Actually, that study did not conclude that the beavers planned the direction of fall, only that there was a correlation between the direction of fall and the direction of the damn. I'll wait and see if anyone else can dig up some more recent/conclusive study, but I have been unable to and will likely accept your answer later. $\endgroup$
    – canadianer
    Commented Jul 9, 2015 at 21:01
  • 3
    $\begingroup$ There's this paper, which finds that the direction a beaver cuts from is related to the terrain slope, tree lean and distance from the shore, which implies that they are felling directionally. $\endgroup$
    – canadianer
    Commented Jul 9, 2015 at 21:07
  • 1
    $\begingroup$ Sorry, I meant to link to this paper: kb.osu.edu/dspace/bitstream/handle/1811/23987/… $\endgroup$
    – canadianer
    Commented Jul 9, 2015 at 21:19
  • 1
    $\begingroup$ This is exactly what would be expected: beavers would be expected to try to fell directionally (towards the dam or, if necessary, avoiding obstacles) as there is an advantage to the individual and therefore an evolutionary advantage. On the other hand (especially regarding obstacles) they would not be expected to show the same degree of judgement as an experienced human lumberjack. $\endgroup$ Commented Jul 10, 2015 at 1:08

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .