09/08/2026
Beavers do not need an actual stream to start damming something. In Lars Wilsson’s 1960s experiments, the sound of running water alone could set captive beavers building.
That made noise itself an unexpectedly powerful cue.
Wilsson raised young Eurasian beavers without adults, and animals that had never watched a dam being built could still construct one.
He then played recordings of flowing water through a loudspeaker in still water and even on dry concrete. The beavers piled sticks, mud, and other material toward the sound, sometimes covering the speaker.
Wilsson described the behavior in his 1968 book My Beaver Colony and a 1971 Stockholm University dissertation.
Later research showed sound is not the only cue, but it can strongly guide dam building and repair.
Today, beaver-management devices use that insight by moving water more quietly through dams.
For a beaver, a trickle can sound like unfinished construction.