Nature’s Lumberjacks

New research shows that juvenile beavers master the art of directional tree felling by copying adults in the most advantageous approach to a tree and placement of the initial cut. Here, an adult female and her son from last year alternate in cutting a large Douglas fir near a forested lake in northern Montana in the United States. Cuts at different height on opposite sides of the trunk enable the most efficient and safest tree felling. Still, an adult pauses periodically to assess tree angle and stability. Cameras mounted high in the canopy and fired remotely from about 50 m away, just outside of a tree fall reach, were instrumental in discovering crucial aspects of tree cutting behavior in this beaver colony.

Photograph by Alexander Badyaev

A female beaver (Castor canadensis) and her one-year-old kit take turns gnawing a large Douglas fir (Pseudotsuga menziesii) near a lake in northern Montana. New research suggests that juveniles master the art of directional tree felling by copying adults, learning how to approach the task and where to place each cut. By gnawing at different heights on opposite sides of the trunk, the beavers work together to fell the tree efficiently and in the desired direction, the female pausing regularly to assess the tree’s angle and stability. Cameras mounted high in the canopy, and fired remotely from just outside the “falling tree zone,” were key to uncovering crucial aspects of tree-felling behavior in this family group. The obvious risk to the photographer’s cameras was deemed a reasonable price to pay.