NewsMontana and Regional News


A Wilder View: Why beavers build dams

Posted at 11:57 AM, Oct 19, 2022

MISSOULA - A big drive and big teeth are all beavers need to build a dam.

So why do they do it?

The key reason beavers build dams in the first place is for protection from predators like mountain lions, coyotes or bears.

But those sticks aren’t the line of defense you might think. It's important to point out that beavers don’t actually live in dams, they do make a place to live called a beaver lodge.

The cozy home is built out of twigs, sticks, rocks, and mud.

Inside their lodge, beavers have a safe dry place to sleep, raise their young, stay warm in the winter, and even store food.

The true reason they build their dams is to create pools of deep water.

This deep water is what actually protects them from predators.

Much like people, they are modifying their environment to be more comfortable and secure.

Because they are semi-aquatic animals, beavers escape lurking predators by diving underwater.

This provides a much safer place to hide out than shallow streams.

Not only are these areas of water deep enough to deter animals that cruise on land, but they also allow beavers to dig underwater entrances into the lodge.

This means that if danger presents itself, they can safely escape through these hidden tunnels.

Since beavers significantly change the surrounding areas and ecosystems they are termed as eco-engineers.

The pooling water caused by dams can create wetlands which provide excellent areas for other animals to live and thrive.

Their dams also may cause flooding which can push dead trees down and create snags that attract an abundance of insects and fish.

Beaver lodges are more than just a home for them to reside in.

It can house animals like muskrats, mink, and even river otters.

Beaver lodges further grant cover for fish, and some birds will even nest on top of these homes.

We of course know all these dams and lodges require a lot of wood work.

A beaver's incessant drive to cut down trees is accompanied by its famous teeth.

Like all rodents, a beaver's teeth never stop growing.

Gnawing on trees helps keep their teeth from getting too long, and keeps them sharp, strong, and healthy.

All this impact from moving trees as an eco-engineer makes them a keystone species which means they have a large influence on the wildlife around them.

Beavers create habitats for insects, birds, fish, amphibians, reptiles, and mammals; which all rely on this habitat for their survival.

In his book Eager: The Surprising Secret Life of Beavers, Ben Goldfarb said “beavers are nothing less than continent-scale forces of nature and in part responsible for sculpting the land upon which Americans built their communities.”

Where beavers go wildlife follows.

So, ensuring beavers stay alive means conserving an entire ecosystem.