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. [OPEN] Ok, so what do most people know about beavers? 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! If you want to see more of Alaska’s incredible
wild life, watch Wild Alaska Live, a special 3-night live event brought to you by PBS and
BBC. Check the description for more info. 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.
