The Burrowers - Learning Zone

The great British countryside is full of wonderful wildlife.

But some of that wildlife can be really tricky to see.

You see, it lives in homes, just like we do,

but its homes are hidden deep beneath the ground.

But now, for the very first time, we're going to dig into the ground,

so that we can show you the secret lives of the burrowers,

animals like badgers, rabbits, water voles and moles,

and you're going to see them in a way

that they've never been seen before.

I bet you can't guess what this is.

It looks strange.

It could be a piece of art or, perhaps, a dead tree

that's fallen over, but this used to be underground.

It might be hard to imagine, but this used to be a rabbits' home,

a warren, and these are tunnels and rooms

which we call chambers.

We poured concrete into an old warren.

Don't worry, we made very sure there weren't any rabbits inside.

Then we waited until the concrete went hard

and then we dug around the soil so we could see

the shape of the warren.

So what you're looking at now is a warren from the outside,

and it's amazing.

All those times that I was walking across the UK countryside,

stepping over rabbit holes in the ground,

I never knew what was beneath that soil

and now I can see it easily.

Question is, of course, what can we learn from this?

There are over 45 million rabbits in the UK,

and the best time to see them is in the summer.

We know quite a lot about how they live when they're above the ground,

but Dr Sasha Norris is going to tell us a bit more about how

they live when they're underground, in their warrens.

So, Sasha, what do you think, then?

My first impressions are how much it looks like tree roots,

and I guess that you can expect that, because, obviously,

the tree and the rabbit are doing the same thing,

they're trying to find their way through the soil

and there's going to be hard patches,

there's going to be rocks, bits they just can't get through,

so they have to go sideways.

I also love the architecture of the actual cement,

-where you can see literally the paws of the rabbit...

-You can.

..the claws making the, er...

You can, look at that, you can see it on there,

where the rabbit's claws have actually cut into the soil.

It's been preserved for ever.

And over there there's a rabbit roundabout, Chris.

A rabbit roundabout?

So this is your rabbit hub, is it?

Yeah, I mean, this is right in the middle of the warren, really,

and this is a place where there were seven tunnels coming

off a central node

and, I think, what's interesting is if you imagine a predator...

You know, being pursued by a predator that can enter the warren,

like a stoat or a polecat, you've got lots of escape routes.

So the warrens keep rabbits safe from predators -

animals that might eat them.

But the main thing a warren does is to be a home.

To see inside a rabbit's home, we built our own warren.

Using cameras, we can watch how the rabbits live.

Lots of rabbits might live in a warren like this.

By the end of the summer,

there might be up to 60 rabbits in the warren - adults and babies.

It's full of tunnels and rooms, or chambers,

but everyone knows their place and the most important rabbits

get all the best rooms.

There's very little privacy.

You're going to have young rabbits, they're inexperienced,

they're kind of bumbling around, entering all areas of the warren,

and it's, yes, it's going to get stressful, it's going to get hot,

it's going to get stuffy, it's going to get busy...

You're going to be bumping into rabbits all the time.

It gets very crowded in the warren.

It can get so crowded that some rabbits have to leave.

The most important rabbits will pick the best places to live

and other, less important, rabbits will have to go

and live somewhere else.

It sounds a bit mean, but it's just the rabbit being practical.

There's not enough room for all of them in the warren

and, if they all stayed there, there wouldn't be enough food

for them all, either.

So, we've learned a lot from using the cement to show us

what a rabbit warren looks like.

We've seen how rabbits burrow through soil

and use tunnels for escape.

I never thought I'd get to see exactly what a rabbit warren

looks like underground and it is totally amazing.

I'm very excited,

because on the other side of this door is a magical place.

We built a special rabbit warren, just like a real one.

Inside, we can study and film a group of rabbits

and learn about how they behave when they're hidden from sight

under the ground.

Warrens are made up of tunnels and rooms, which we call chambers.

In one of the most comfortable chambers,

the female rabbit is having her babies.

Look closely...

..this is the moment of birth.

The baby rabbits are called kits.

When they're born they're naked,

so they have to squeeze together to keep warm.

Dr Sasha Norris uses a special camera that sees heat and not light,

so we can see the kits when they're still very, very young.

They can't see, they can't hear, and they've got no fur.

We can see a few of them here, you can see their little ears here

and, look, here are the feet and there's the tail.

-There's the little tail, tufty tail.

-Classic rabbit's tail there.

Just like human babies, the kits need milk from their mothers,

and she usually goes back to the nest once a day to feed them.

-And here, here she comes.

-Here she comes, yeah.

-There she is.

-Look at that one, he's out straightaway.

OK, how many seconds does it take for them to latch on?

Yeah, oh look, this one's just struggling to get in now.

She's over the nest and they're all trying to latch on.

They're all kneading at her belly to get the milk to flow,

the milk doesn't flow immediately, but when it starts to flow

and they're all latched on, there's a high pressure jet of milk

straight into their mouths. She gets that feeding over very quickly.

Seeing the rabbits in a warren like this

tells us a lot about how rabbits live.

It's warmest in the middle of the huddle, that's the best position.

So the kits shuffle about a lot.

No-one wants to be around the edges.

The kits aren't trying to keep warm just because it feels nice,

experts now think that the warmth helps the baby rabbits

digest their mother's milk.

Soon the kits are old enough to eat solid food,

and it isn't what you'd think.

A rabbit's first ever meal is its mum's poo.

You can often find rabbit poo in places like fields and farms.

Rabbit poos are called pellets

and they look a little bit like raisins covered in chocolate.

Dr Sasha Norris has found some we can look at

and she can explain why the poo makes healthy food for baby rabbits.

These are your traditional rabbit pellet that you

find above the ground when you're walking in the countryside,

You break it open, it smells like hay.

Yeah, just smells of grass.

-Yeah, what have you got?

-I've got something a bit more interesting

-and certainly a lot more smelly.

-Oh!

So rabbits have two types of poo, and, believe it or not,

it's the smelly pellets that make the best food for babies.

Adult rabbits produce the smelly poo

after they've eaten lots of tough plants.

The plants are hard to digest

and the rabbits can't manage them all in one go.

So when they have a poo,

it's a mixture of the plants they can't manage to digest

and important bacteria that help break down the food.

Now the baby rabbits can eat the smelly pellet safely

because they're still full of goodness from the plants.

It might sound really yucky,

but this makes a great first meal for baby rabbits.

They get lots of goodness from the plants in the poo.

It's also full of good bacteria that will help

the kits' stomachs to become strong.

They need a strong stomach so they can break up tough plants

when they're older. They'll carry on eating their own poo

and they'll be feeding babies of their own.

Rabbit poo might be good for baby rabbits,

but it's not good for humans,

so don't try this at home!

Many animals have underground homes.

The biggest in Britain are badgers.

They live in family groups in homes we call setts.

This is a special sett that we've built

to be as much like a badger's real home as possible.

We've got cameras inside

and it means that we can see what badgers get up to

when they're underground.

You can see that our badgers are very sociable.

They like to live with each other and they love to play.

In the wild, badgers like to dig their setts

in the middle of a large area, which is known as their territory.

This is a stretch of land where they go to look for food.

So now I've come to see exactly what a real badger territory looks like.

Now, where I'm standing at the moment is at the top

of a badger's territory that's been mapped and measured.

It runs down this side here,

down through the woodland towards the banks

of the reservoir behind me over there for about 1,000 metres

and, in terms of its width, it stretches across this slope

for about 500 metres.

We can see that a family of badgers can have a really big territory

and I want to find out how they use all of that space.

Badger expert Dr Chris Cheeseman has been watching badgers

for over 35 years, so he knows a lot about them.

He's found the entrance to what is known as the main sett.

-That's quite busy, Chris.

-Yeah, this is an active hole.

Some bedding here, that's just been taken down.

Some fresh hairs, a few prints.

This sett looks like it's been here a long time.

Yes, it's a well-established sett.

I would say that this is part of the landscape,

it's a good main sett, sort of, situation.

We call this the main sett because badgers have more than one sett.

Badgers like to live in the main sett for most of the year.

This is where they'll have their litter of babies.

This main sett might have been here for hundreds of years.

There are other setts as well, but they are all smaller.

They're like a second home for the badgers.

We're going to see if we can find one.

This is still a badger sett, and we're about, well,

a few hundred metres from the main sett here.

This is what we call an outlying sett,

as opposed to that big headquarters, the main sett.

The badgers use the small setts in the spring, summer and autumn,

when there's lots of food around.

They can go out to find their dinner

and then pop into one of the smaller setts for a little rest.

So the small setts are really useful.

There might be up to six in each badger territory.

Badgers are really smart to have their main home

and a few other homes as well.

Wouldn't that be nice?

Badgers are really good at knowing which territory is theirs

and what belongs to other families.

Let's take a closer look at the badger territory

that I've been exploring.

I love a map, and here's a map which identifies

all of the significant features of our badger's social group.

Firstly, the main sett, it's here,

pretty much in the centre of their territory.

The other red spots here identify the sub setts.

These closer to the edge, well, these are useful boltholes.

In the past, when there were predators, the badgers would have

needed to have nipped into those, perhaps, if they were under attack.

Badgers usually stay in their own land.

If they go into territories where other badgers live,

they might be chased out.

It might sound a bit strange but badgers know which bit of land

is theirs and which bit belongs to other badgers.

They know this by their toilets, which are known as latrines.

Badgers have really distinct smelling poo,

which they put at the edge of their territories,

so other badgers know they shouldn't enter.

It's all very carefully planned, as you can see from my map.

And around the edge of that,

to mark it very clearly for all of the badgers,

are the territorial latrines,

which I've marked here in blue.

So as you can see, rather than being a random collection of holes

placed in a wood somewhere, this system of setts,

and their placement within the territory,

is actually quite sophisticated

and it's essential to the survival of these animals.

Badgers are very social animals.

They like to live with each other in homes known as setts.

Inside their burrows, all the badgers know their place

and where they belong in the group.

This is a sett we built especially to be as close

to nature as possible.

It means we can study and film badgers behaving like they

would in the wild and it's great to be able to watch them this close up.

It strikes me that if our young badgers aren't eating,

and they're not sleeping and they're not playing,

then what they're doing is grooming.

They spend a lot of time on their personal hygiene

and, of course, grooming one another.

Badgers obviously like to keep clean.

This is just how badgers behave in the wild as well.

Sometimes they will scratch for up to ten minutes.

A bit like us coming in after a hot, sweaty day,

getting into the shower and scrubbing furiously,

and there's a real sense of joy about it, as well.

There's a very good reason why badgers like to keep clean.

Lots of tiny insects like to live on badgers,

because their fur is cosy and warm.

There are even little insects called fleas that feed on badger blood.

So it isn't really surprising that badgers spend

so much time grooming or cleaning themselves and each other.

How would you like to be covered in blood sucking fleas?

Chris Cheeseman has been studying badgers for over 35 years,

so he knows lots about them and why fleas like them so much.

Fleas need a badger to suck blood from, get a blood meal,

and they also need somewhere to lay their eggs.

They don't do it on the badger, they do it in the badger's nest.

The eggs will hatch out in the bedding,

the larvae will develop there.

When they hatch into fleas, eventually,

off they go again, find an adult badger to suck blood from.

That's the life cycle, basically.

That means that the badger's bedding is full of fleas,

and that it's really uncomfortable for them.

To get around this, the badgers like to change their bedding all of the time.

Badgers have the habit of collecting bedding

from any sort of bedding, like straw, hay, dead leaves.

They bring that into the nest chamber

and, after a while, it does get infested

and the badger will take it back out

and they do scatter it quite well.

Now, when it's out there, exposed to sunlight...

-That's going to kill the larvae.

-It's going to kill the larvae and it's going to make it hard

for the fleas to survive. So it's a good way of keeping that parasite burden down,

to take your bedding out and air it.

So badgers are really wise to air their bedding

and also very clever about what they choose to make their beds from

in the first place.

It's really interesting that badgers like to use

all different types of plants for their bedding.

They do bring in fresh, green bedding.

I've seen them dragging in lots of fresh green bracken,

and other plants are often brought into the nest, aren't they?

Well, one that's frequently brought in, and it really is smelly,

is garlic. Wild garlic.

-They'll bring in huge quantities of fresh, green garlic leaves.

-Mm.

I'm sure the fleas don't particularly like that,

so, maybe, garlic helps keep fleas, ticks

and lice away from the bedding.

So badgers use lots of types of bedding for different reasons,

and they're clever enough to know that smelly plants like garlic

help to keep the fleas away.

It's their very own natural insect repellent.

One burrower, the most secret of them all,

spends almost all of its time living alone.

The mole.

Moles live underground all of the time.

They never leave their burrows.

We've built a special burrow

so we can study how moles live underground.

Their bodies are really good for living underground,

where there's not much air, because even though they're really active

and do lots of digging, they need much less oxygen than human beings.

There's no light underground, and the moles have bad eyesight.

But over millions of years moles' bodies have adapted

and changed to help them live underground.

So even though they can't see very well

the moles make up for it with their noses.

A mole's nose has a special bit for feeling.

It's called the Eimer's organ.

It's made up of special parts

that let the moles feel every bit of their burrow.

Moles feel with their tails as well.

Of course, that's really important, as they're almost

blind in this totally dark place.

You can see here what looks like an extra finger,

although it isn't, really.

Look closer and that sixth finger is actually a type of thumb.

Moles use their wide hands as if they were a specially made spade.

This is another example of how moles' bodies have adapted

and changed to make their lives underground easier.

The mole uses its burrow to catch earthworms.

It likes to bite off their heads so they can't move

and then the mole can come back when it's hungry and eat them later.

As the mole digs through the soil they seem to move really easily.

How they dig looks familiar.

It makes me think of another animal.

This is Starburst and her sisters and they are common seals,

and you might think I've gone a bit mad looking at seals,

when I'm talking about moles,

but there are some parallels between these species.

And one is that they both live in a 3-D environment.

The moles are living surrounded by soil

and these things are surrounded by water.

Where the animals live has changed the way they move.

This is because of their anatomy,

that's the way their bodies are designed.

So I want to know how a mole's body compares to a seal's.

Come on.

For a start, seals have very streamlined bodies

for slipping easily and gracefully through the water,

just as moles have streamlined bodies

for pushing their way through the soil.

Now, these animals don't have their limbs beneath their body

to support their weight,

because for seals the water is supporting that body weight.

And they have their forelimbs on the side of their body,

just like moles do.

And moles and seals have even more in common.

We can learn about this by looking at skeletons, or bones,

of both animals.

This is Peter Stafford, who knows a lot about moles.

What have we got here then, Peter? Looks like a seal skeleton

and a mole skeleton for a bit of comparative anatomy to me.

Yeah, you're spot on, Chris, that's exactly what it is.

Let's start at the back end, then, the tail,

because in both animals it's very short, isn't it?

Yes, compared with the overall size of the body,

it is, indeed, very short,

and would serve very little obvious function in its normal daily life.

Looking at the skeleton of both, very streamlined,

this one for slipping through water

-and this one for pushing through soil, of course.

-Yes, indeed.

Very streamlined, and there is this particular similarity,

which I've always said that moles tend to swim through the soil

rather than burrow, or dig, through it.

They do this through the soil rather than what we perceive as burrowing.

The seal here has got its hands, if you like,

which have evolved into these large paddles for pushing itself

through the water, and the mole, well, has no parallel, does it?

No, I mean, they're spades, aren't they? Well, they're shovels!

So, here we are then, this is an animal that swims through the sea

and here we have an animal which, through similar adaptations,

-swims through the soil.

-That's exactly what they both do.

So even though moles and seals are very different animals,

they do have a lot in common.

Their bodies help to make digging and swimming easier.

Even though they're completely different to look at,

they move in a similar way.

Water voles are one of Britain's rarest burrowers.

They're an endangered species and there aren't many of them

left in the United Kingdom.

You might know them from the famous children's book

Wind In The Willows.

The main character, Ratty, was actually a water vole

and not a rat at all.

We built a special burrow so we can study and film water voles.

Burrowing animals have a lot of things in common,

but one thing that makes water voles different

is that, as well as living underground,

they like to be...

in the water.

Water voles live alongside each other in burrows

made in the side of rivers.

Around their burrows is the land and water called their territory.

Stretching down this lovely river in Devon

are a whole lot of water vole territories,

which means that their burrow system will be running

for hundreds of metres up and down these banks,

and we can see some of the tunnels that have been exposed here.

These tunnels will go right into the bank, as far as six metres,

and sometimes, when there's lots of predators,

things like stoats and weasels,

they'll even make amends for that by making special shaped tunnels.

Some will go in beneath the water surface,

making their life difficult, others, above the surface

but then with a U-bend, which floods full of water,

so those stoats and weasels can't get through it

and the voles remain safe.

Water voles like the river as it gives them

everything they need to survive.

The banks give them a nice spot for a home,

and they can also use the river to find food.

Of course, because they live by a river,

water voles need to be strong swimmers,

and baby water voles have to learn to swim, just like the rest of us.

Water vole babies are called pups.

They're born underground.

They don't go outside until they're 14 days old.

Swimming lessons can get off to a slow start.

The water voles might be nervous and stay by the water's edge...

..but not for long.

Very soon they'll be strong, confident swimmers,

just like their mums and dads.

It's no wonder that baby water voles are so good at swimming.

Their bodies are made for water.

They have waterproof fur, which means that even if they get

their heads wet, they can usually dry them off with a single shake.

Water voles are an example of an aquatic mammal.

These are animals that can swim.

But there is something about the vole's feet that's unusual.

I've got a great view of his feet here.

For an aquatic mammal, you'd expect webbing.

Beavers, otters, they both have webbed feet. But water voles don't.

In fact, you can see these voles have gaps between their toes,

and I'm really surprised by that.

It's really lucky for voles that they're good swimmers,

as they often have to get away from predators in the water

and on the land.

One of the main enemies of the vole is the American mink.

These animals were brought over to the UK in the 1930s

and the water voles have no way of hiding from them.

When water voles are above ground,

they do their best to stay out of sight.

So they make little covered passageways in the undergrowth,

called runs.

These lead from their burrows to the water

and they're also great hiding places.

In here is a run that's been made through

some of the tussocks in the grass by the water voles.

They've come up the bank, where I can see that there's some bare mud,

they've been frequent in their visits,

but, look here, if I part the grass,

you can see that between the tussocks

there's a neat little covered run.

Because it's covered with all of this grass,

it's offering them protection from predators, they can't be seen.

And, as the water voles can't be seen,

it means that they can hide important things here,

like their favourite foods.

Oh, look at this!

Down in here looks like...

..water crowfoot, or something like that,

and they've snipped it off into these packages,

something that they can carry very easily,

and then moved it here to the security of this tunnel,

so that they can eat it without the risk of being spotted

by anything that wants to eat them.

That's like a little water vole breakfast bar down there.

So if you want to see a water vole in the wild,

the best thing to do would be to go and have a look near a river bank.

You may not be able to see them swimming,

but you might see the entrance to their home.

Make sure you take an adult with you,

and don't go too close to the edge of the water.

And, remember, be very, very quiet.

Our special filming in the burrows that we made

for all of our animals has shown us some really interesting things.

But, you know, one thing that it's made me realise

is just how little we know about these animals' lives.

The lives that are happening just here beneath our feet.

But at least we've revealed some of their secrets,

some of their beauty, and some of their wonder.

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