Beavers are the ultimate climate warriors.
That's why we call them ecosystem engineers.
Their dams reduce flooding, prevent droughts,
capture carbon, purify water and increase biodiversity.
But they've been extinct in Britain for 400 years.
Until recently.
Beavers totally transform the landscape,
creating whole ecosystems from scratch.
And here's how they do it.
Hi, I'm Heather Devey and I work with
beavers in northern England. Now at
the moment we're at the Lowther Estate near Penrith
in the Lake District because last year
they released two beavers into an enclosure
as part of an enclosed trial release.
And what has been brilliant is
I've been coming to this site for the past year
to monitor the impacts the beavers have had.
And let me tell you, it is incredible.
So it's all part of the estate returning
the landscape to nature, giving over a little
bit of control so that nature takes its own route
and still continuing farming on the estate as well.
Beavers and humans actually co-evolved,
and in Britain, we coexisted with beavers
right up until around 400 years ago,
and we actually hunted beavers to extinction
in the first place for their meat, for their fur,
particularly for the hat industry.
But instead of looking to the past,
now we're looking to the future and how we can
once again learn to live alongside beavers.
Okay, here we are at our first beaver feature,
and where better to start than with a beaver dam.
Now beavers are stimulated to create dams
because they need around a metres depth of water
to feel secure. If they don't have that,
they'll chop down some trees, they'll take
the upper branches and then they'll pull it into
the water system and pack it in with mud and stones.
And that's exactly what the Lowther pair did
when they first arrived.
Admittedly, this dam is a little bit humble.
But from where it started in October last year,
it's really increased in height and in length.
And that's the brilliant thing about beaver dams.
Beavers actually respond really quickly to
changes in the environment,
so they work with the water table.
If rains increase, they might
increase the height of dam, they might
add a notch to let water through occasionally.
But overall prerogative of beavers is to hold water back.
And to do that, they don't just create one dam.
They create a really complex network
within a wetland and that creates a really
dynamic ecosystem. That is why beavers are known
as ecosystem engineers.
They create these ecosystems entirely from scratch,
and they do it for free.
Not only do these beaver dams actually benefit
beavers, they help with biodiversity overall.
So birds benefit, fish benefit, small mammals,
amphibians, freshwater invertebrates,
a whole diversity of life.
The wetlands beavers create, along with the silt that
builds up behind dams, become massive carbon sinks.
Wetlands are actually the most important habitat for
carbon sequestration and could be our
secret weapon for fighting climate change.
And, us included, because if you listen carefully
that trickling of water shows that the flow of water
is going really slow through this beaver dam.
And when it's a complex network of dams like this,
it helps to slow the flow of water downstream.
Some sites have actually found a 30 percent reduction
in peak flow rates because of beaver dams,
which is no bad thing.
Other studies have found
a 60% reduction.
This is really important because it means that
during storm events or heavy rains
the flow of water is slowed down
by the complex network of dams,
protecting what's downstream.
For example, towns or villages.
This holding back and slowing of water
through the dam systems has another benefit.
It helps filter out any potential harmful chemicals
that can run into the waterways
from agricultural fields or urban areas.
Now any self-respecting engineer needs
a really good tool kit
and beavers come fully equipped.
That's because they've been evolving this
aquatic rodent lifestyle for millions of years.
For example, they've got a rudder-like tail
and webbed hind feet to help aid with their swimming.
On top of that, their nostrils close when they dive,
as do their ears and a part of their mouth
to prevent water from entering their bodies
when they dive underwater.
But there's another anatomical feature that really
comes in handy when we go and have a look at
this second feature.
So onto beaver feature number two
and that is felled trees.
Now if you're in a beaver habitat,
you're very likely to see these.
Not only do the beavers need them to create their dams,
they actually switch to a woody diet in the winter.
Because beavers are herbivores, they eat vegetation
and these woody trees as well.
They don't eat anything else like fish.
So when beavers actually coppice a tree,
they need that other anatomical feature.
And of course, that's their front teeth, their incisors.
And if you've seen beaver teeth before,
they're really bright orange.
And that's because they're fortified with iron,
really strong tools for the job of chopping through wood.
Now when the Lowther beavers arrived,
this is the first tree that
they actually set to work on coppicing.
And as you can see, just after a year,
there's a huge amount of regrowth.
It grows back as a bit of a shrubby underlayer,
which is brilliant for invertebrates,
brilliant for small mammals
and really great as well for nesting birds.
Because this shrubby habitat is actually quite
rare to come by when it comes to succession
in these kinds of habitats, the wetlands.
So let's head on to their transport networks
to create these systems,
and that is feature number three.
Now the third feature that not many people
are aware of that beavers create, are channels
and they create these by
digging them out with their forefeet.
And these are brilliant networks for other
species too such as amphibians and fish.
Now when it comes to fish and beavers,
it's been shown that beaver pools actually
greatly benefit fish mass and diversity in age.
So these networks actually act as transport channels
for wildlife, but also for the beavers
to drag their building materials through.
Of course, beaver impacts are going to vary
according to each site, and in some situations
we will need to work with them,
such as installing tree guards to protect trees
or putting flow devices through dams
to alter the height of water.
But with enclosed trial releases and free living
beavers around parts of Britain now,
it's really important that we work together
to welcome back nature's ally to join our battle
against the impacts of climate change
and the biodiversity crisis.