Why do beavers build dams?
For grown-ups: the science
Beavers build dams to make deep, calm ponds that help protect their homes.
Beavers build dams primarily to create and maintain deep water around their lodges and bank dens. Water helps them access underwater entrances and reduces access for many land predators; dams can also maintain water depth during low-flow periods. They use woody material, mud, and sometimes stones, adjusting dams in response to flowing water.
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Transcript
A beaver splashes in a little stream. Why does it build a dam?
Beavers stack branches, mud, and stones across moving water. The dam slows the stream and makes a deeper pond.
In the pond, a beaver can swim to its home more safely. Its home often has an underwater doorway.
The pond also keeps water near the beaver's home when the stream gets low. Beavers use the pond as a safe place to live.
So beavers build dams to make deep, calm ponds around their homes.