One of my favorite things to do on this channel is to get you to look at the world you know
in a different way, to take something you thought was ordinary, and show you why it’s
amazing.
Today I’m here in Alaska, and you’re never gonna look at beavers the same way again.
They chew down trees, and they build dams.
But what most people don’t know is without beavers, North America–and much of the world–would
be totally different than it is today.
Beavers are one of the ultimate keystone species—a plant or animal so important to an ecosystem,
that without it, the whole thing would basically break.
Their dams create habitats for dozens of species, filter and purify water, and enrich the soil
by trapping sediment and nutrients.
Beaver ponds reshape landscapes on such an enormous scale it impacts all other wildlife
and vegetation in the area.
Earth is home to two beaver species today: one in Europe, and these here in North America.
They’re the second largest rodents living today, and like most rodents they have big
front teeth that never stop growing.
Beaver teeth are actually reinforced with iron, and with their enormous jaw muscles
they use those teeth to slice through bark and chop down trees.
Besides being carpenters, they even play the part of plumbers.
When a beaver hears the sound of running water, it drives them nuts, they know the dam has
sprung a leak and they have an uncontrollable instinct to go patch it up.
Beavers are ecosystem engineers second only to humans, and they stay pretty DAM busy keeping
this pond nice and full.
Beavers’ urge to build can sometimes cause headaches, but NO beavers can be an even BIGGER
problem.
Before European colonists arrived, there were as many as 400 million beavers in the US and
Canada!
North America was covered with tens of millions of beaver dams.
Imagine between 5 and 30 beavers on every kilometer of stream or river on the whole
continent!
That’s a lotta beavers.
But over a few hundred years they were almost hunted to extinction.
Beavers were big business.
They were trapped for fur, mostly to make hats, but also for sacs on their butts full
of castoreum—a pungent substance used in perfumes.
The British Hudson’s Bay Company even tried to eradicate beavers from the Pacific Northwestv,
figuring with no beavers left to hunt, the United States would stop its westward expansion.
Wherever pioneers went, they killed every beaver they could find, despite the fact that
beavers were responsible for most of the farmland in the West.
Populations dwindled from millions to the low thousands.
Without beaver dams, huge areas of land are left with less water.
hundreds of species (like fish, birds, insects, and amphibians) are left without a habitat.
So… beaver dams are great for other species, but what’s in it for the beavers?
Why do they build them?
For beavers the pond created by their dams is a safe place to build a home, called a
lodge, where they raise their young and keep away from predators.
Beavers are pretty awkward on land, but they are safe and happy in the water.
The entrance to a beaver lodge is underwater, so beavers can safely scoot in and out.
Since they don’t hibernate, this lets them access underwater food stores even when their
ponds are frozen over.
Beavers’ favorite foods are the leaves and soft outer bark of trees, but like most mammals,
they don’t digest wood very well, so they eat their excrement to get the most out of
a meal… until it eventually comes out looking like sawdust.
A crew of beavers spotted in a pond is usually a family.
Beaver couples often mate for life and beaver kits live with their parents for a couple
years while they practice their engineering skills.
The oldest dams ever discovered are 100,000 years old telling us beavers or their close
relatives have been altering our landscapes even before we moved in.
And for most of the thousands of years we’ve lived together, we’ve lived in harmony.
Now that we’ve realized how important they are, beaver populations are starting to recover.
More beavers means more homes for fish and birds, fresher water, and less damage
from flooding and forest fires.
Beavers feature prominently in the oral histories of North America’s First Nations people,
even playing a part in many creation myths, which is neat, because beavers really have
created much of the landscape we live in, showing us how old and important our relationship
is with the smartest thing in fur pants.
Stay curious!
Beavers are big as rodents go today, but during the Pleistocene, Earth was home to a beaver
called Castoroides the size of a black bear.
Too bad they went extinct.