0:00:02 > 0:00:04The great British countryside is full of wonderful wildlife.
0:00:04 > 0:00:08But some of that wildlife can be really tricky to see.
0:00:08 > 0:00:11You see, it lives in homes, just like we do,
0:00:11 > 0:00:15but its homes are hidden deep beneath the ground.
0:00:16 > 0:00:20But now, for the very first time, we're going to dig into the ground,
0:00:20 > 0:00:24so that we can show you the secret lives of the burrowers,
0:00:24 > 0:00:28animals like badgers, rabbits, water voles and moles,
0:00:28 > 0:00:31and you're going to see them in a way
0:00:31 > 0:00:33that they've never been seen before.
0:01:07 > 0:01:10I bet you can't guess what this is.
0:01:11 > 0:01:14It looks strange.
0:01:14 > 0:01:16It could be a piece of art or, perhaps, a dead tree
0:01:16 > 0:01:21that's fallen over, but this used to be underground.
0:01:21 > 0:01:25It might be hard to imagine, but this used to be a rabbits' home,
0:01:25 > 0:01:29a warren, and these are tunnels and rooms
0:01:29 > 0:01:30which we call chambers.
0:01:32 > 0:01:34We poured concrete into an old warren.
0:01:34 > 0:01:39Don't worry, we made very sure there weren't any rabbits inside.
0:01:39 > 0:01:43Then we waited until the concrete went hard
0:01:43 > 0:01:46and then we dug around the soil so we could see
0:01:46 > 0:01:48the shape of the warren.
0:01:48 > 0:01:52So what you're looking at now is a warren from the outside,
0:01:52 > 0:01:54and it's amazing.
0:01:55 > 0:01:59All those times that I was walking across the UK countryside,
0:01:59 > 0:02:02stepping over rabbit holes in the ground,
0:02:02 > 0:02:05I never knew what was beneath that soil
0:02:05 > 0:02:09and now I can see it easily.
0:02:09 > 0:02:12Question is, of course, what can we learn from this?
0:02:14 > 0:02:19There are over 45 million rabbits in the UK,
0:02:19 > 0:02:22and the best time to see them is in the summer.
0:02:22 > 0:02:25We know quite a lot about how they live when they're above the ground,
0:02:25 > 0:02:29but Dr Sasha Norris is going to tell us a bit more about how
0:02:29 > 0:02:33they live when they're underground, in their warrens.
0:02:33 > 0:02:34So, Sasha, what do you think, then?
0:02:34 > 0:02:38My first impressions are how much it looks like tree roots,
0:02:38 > 0:02:41and I guess that you can expect that, because, obviously,
0:02:41 > 0:02:44the tree and the rabbit are doing the same thing,
0:02:44 > 0:02:47they're trying to find their way through the soil
0:02:47 > 0:02:49and there's going to be hard patches,
0:02:49 > 0:02:51there's going to be rocks, bits they just can't get through,
0:02:51 > 0:02:54so they have to go sideways.
0:02:54 > 0:02:57I also love the architecture of the actual cement,
0:02:57 > 0:03:00- where you can see literally the paws of the rabbit...- You can.
0:03:00 > 0:03:02..the claws making the, er...
0:03:02 > 0:03:04You can, look at that, you can see it on there,
0:03:04 > 0:03:07where the rabbit's claws have actually cut into the soil.
0:03:07 > 0:03:09It's been preserved for ever.
0:03:09 > 0:03:12And over there there's a rabbit roundabout, Chris.
0:03:12 > 0:03:15A rabbit roundabout?
0:03:15 > 0:03:17So this is your rabbit hub, is it?
0:03:17 > 0:03:20Yeah, I mean, this is right in the middle of the warren, really,
0:03:20 > 0:03:23and this is a place where there were seven tunnels coming
0:03:23 > 0:03:25off a central node
0:03:25 > 0:03:28and, I think, what's interesting is if you imagine a predator...
0:03:28 > 0:03:31You know, being pursued by a predator that can enter the warren,
0:03:31 > 0:03:35like a stoat or a polecat, you've got lots of escape routes.
0:03:35 > 0:03:39So the warrens keep rabbits safe from predators -
0:03:39 > 0:03:41animals that might eat them.
0:03:41 > 0:03:45But the main thing a warren does is to be a home.
0:03:45 > 0:03:49To see inside a rabbit's home, we built our own warren.
0:03:49 > 0:03:52Using cameras, we can watch how the rabbits live.
0:03:53 > 0:03:57Lots of rabbits might live in a warren like this.
0:03:57 > 0:03:59By the end of the summer,
0:03:59 > 0:04:04there might be up to 60 rabbits in the warren - adults and babies.
0:04:04 > 0:04:06It's full of tunnels and rooms, or chambers,
0:04:06 > 0:04:10but everyone knows their place and the most important rabbits
0:04:10 > 0:04:12get all the best rooms.
0:04:13 > 0:04:15There's very little privacy.
0:04:15 > 0:04:18You're going to have young rabbits, they're inexperienced,
0:04:18 > 0:04:22they're kind of bumbling around, entering all areas of the warren,
0:04:22 > 0:04:24and it's, yes, it's going to get stressful, it's going to get hot,
0:04:24 > 0:04:27it's going to get stuffy, it's going to get busy...
0:04:27 > 0:04:30You're going to be bumping into rabbits all the time.
0:04:31 > 0:04:34It gets very crowded in the warren.
0:04:34 > 0:04:38It can get so crowded that some rabbits have to leave.
0:04:38 > 0:04:42The most important rabbits will pick the best places to live
0:04:42 > 0:04:45and other, less important, rabbits will have to go
0:04:45 > 0:04:47and live somewhere else.
0:04:49 > 0:04:54It sounds a bit mean, but it's just the rabbit being practical.
0:04:54 > 0:04:57There's not enough room for all of them in the warren
0:04:57 > 0:05:00and, if they all stayed there, there wouldn't be enough food
0:05:00 > 0:05:02for them all, either.
0:05:03 > 0:05:07So, we've learned a lot from using the cement to show us
0:05:07 > 0:05:08what a rabbit warren looks like.
0:05:08 > 0:05:10We've seen how rabbits burrow through soil
0:05:10 > 0:05:13and use tunnels for escape.
0:05:13 > 0:05:17I never thought I'd get to see exactly what a rabbit warren
0:05:17 > 0:05:20looks like underground and it is totally amazing.
0:05:31 > 0:05:32I'm very excited,
0:05:32 > 0:05:37because on the other side of this door is a magical place.
0:05:37 > 0:05:41We built a special rabbit warren, just like a real one.
0:05:41 > 0:05:44Inside, we can study and film a group of rabbits
0:05:44 > 0:05:47and learn about how they behave when they're hidden from sight
0:05:47 > 0:05:49under the ground.
0:05:52 > 0:05:57Warrens are made up of tunnels and rooms, which we call chambers.
0:05:57 > 0:05:59In one of the most comfortable chambers,
0:05:59 > 0:06:02the female rabbit is having her babies.
0:06:02 > 0:06:03Look closely...
0:06:03 > 0:06:05..this is the moment of birth.
0:06:08 > 0:06:11The baby rabbits are called kits.
0:06:11 > 0:06:13When they're born they're naked,
0:06:13 > 0:06:16so they have to squeeze together to keep warm.
0:06:18 > 0:06:23Dr Sasha Norris uses a special camera that sees heat and not light,
0:06:23 > 0:06:27so we can see the kits when they're still very, very young.
0:06:30 > 0:06:33They can't see, they can't hear, and they've got no fur.
0:06:33 > 0:06:36We can see a few of them here, you can see their little ears here
0:06:36 > 0:06:39and, look, here are the feet and there's the tail.
0:06:39 > 0:06:43- There's the little tail, tufty tail. - Classic rabbit's tail there.
0:06:43 > 0:06:46Just like human babies, the kits need milk from their mothers,
0:06:46 > 0:06:51and she usually goes back to the nest once a day to feed them.
0:06:51 > 0:06:53- And here, here she comes. - Here she comes, yeah.
0:06:53 > 0:06:58- There she is.- Look at that one, he's out straightaway.
0:06:58 > 0:07:00OK, how many seconds does it take for them to latch on?
0:07:00 > 0:07:04Yeah, oh look, this one's just struggling to get in now.
0:07:04 > 0:07:07She's over the nest and they're all trying to latch on.
0:07:07 > 0:07:10They're all kneading at her belly to get the milk to flow,
0:07:10 > 0:07:12the milk doesn't flow immediately, but when it starts to flow
0:07:12 > 0:07:16and they're all latched on, there's a high pressure jet of milk
0:07:16 > 0:07:20straight into their mouths. She gets that feeding over very quickly.
0:07:24 > 0:07:27Seeing the rabbits in a warren like this
0:07:27 > 0:07:30tells us a lot about how rabbits live.
0:07:34 > 0:07:38It's warmest in the middle of the huddle, that's the best position.
0:07:38 > 0:07:40So the kits shuffle about a lot.
0:07:40 > 0:07:43No-one wants to be around the edges.
0:07:45 > 0:07:48The kits aren't trying to keep warm just because it feels nice,
0:07:48 > 0:07:52experts now think that the warmth helps the baby rabbits
0:07:52 > 0:07:55digest their mother's milk.
0:07:55 > 0:07:58Soon the kits are old enough to eat solid food,
0:07:58 > 0:08:01and it isn't what you'd think.
0:08:01 > 0:08:04A rabbit's first ever meal is its mum's poo.
0:08:06 > 0:08:11You can often find rabbit poo in places like fields and farms.
0:08:11 > 0:08:13Rabbit poos are called pellets
0:08:13 > 0:08:16and they look a little bit like raisins covered in chocolate.
0:08:16 > 0:08:19Dr Sasha Norris has found some we can look at
0:08:19 > 0:08:25and she can explain why the poo makes healthy food for baby rabbits.
0:08:25 > 0:08:27These are your traditional rabbit pellet that you
0:08:27 > 0:08:31find above the ground when you're walking in the countryside,
0:08:31 > 0:08:34You break it open, it smells like hay.
0:08:35 > 0:08:36Yeah, just smells of grass.
0:08:36 > 0:08:40- Yeah, what have you got?- I've got something a bit more interesting
0:08:40 > 0:08:42- and certainly a lot more smelly. - Oh!
0:08:42 > 0:08:46So rabbits have two types of poo, and, believe it or not,
0:08:46 > 0:08:50it's the smelly pellets that make the best food for babies.
0:08:50 > 0:08:53Adult rabbits produce the smelly poo
0:08:53 > 0:08:56after they've eaten lots of tough plants.
0:08:56 > 0:08:58The plants are hard to digest
0:08:58 > 0:09:02and the rabbits can't manage them all in one go.
0:09:02 > 0:09:03So when they have a poo,
0:09:03 > 0:09:07it's a mixture of the plants they can't manage to digest
0:09:07 > 0:09:11and important bacteria that help break down the food.
0:09:11 > 0:09:15Now the baby rabbits can eat the smelly pellet safely
0:09:15 > 0:09:18because they're still full of goodness from the plants.
0:09:20 > 0:09:23It might sound really yucky,
0:09:23 > 0:09:26but this makes a great first meal for baby rabbits.
0:09:26 > 0:09:29They get lots of goodness from the plants in the poo.
0:09:29 > 0:09:32It's also full of good bacteria that will help
0:09:32 > 0:09:35the kits' stomachs to become strong.
0:09:37 > 0:09:40They need a strong stomach so they can break up tough plants
0:09:40 > 0:09:43when they're older. They'll carry on eating their own poo
0:09:43 > 0:09:45and they'll be feeding babies of their own.
0:09:49 > 0:09:51Rabbit poo might be good for baby rabbits,
0:09:51 > 0:09:53but it's not good for humans,
0:09:53 > 0:09:55so don't try this at home!
0:10:05 > 0:10:08Many animals have underground homes.
0:10:08 > 0:10:11The biggest in Britain are badgers.
0:10:11 > 0:10:14They live in family groups in homes we call setts.
0:10:16 > 0:10:19This is a special sett that we've built
0:10:19 > 0:10:22to be as much like a badger's real home as possible.
0:10:22 > 0:10:24We've got cameras inside
0:10:24 > 0:10:27and it means that we can see what badgers get up to
0:10:27 > 0:10:29when they're underground.
0:10:29 > 0:10:32You can see that our badgers are very sociable.
0:10:32 > 0:10:35They like to live with each other and they love to play.
0:10:35 > 0:10:39In the wild, badgers like to dig their setts
0:10:39 > 0:10:43in the middle of a large area, which is known as their territory.
0:10:43 > 0:10:48This is a stretch of land where they go to look for food.
0:10:48 > 0:10:53So now I've come to see exactly what a real badger territory looks like.
0:10:54 > 0:10:57Now, where I'm standing at the moment is at the top
0:10:57 > 0:11:00of a badger's territory that's been mapped and measured.
0:11:00 > 0:11:01It runs down this side here,
0:11:01 > 0:11:04down through the woodland towards the banks
0:11:04 > 0:11:07of the reservoir behind me over there for about 1,000 metres
0:11:07 > 0:11:11and, in terms of its width, it stretches across this slope
0:11:11 > 0:11:14for about 500 metres.
0:11:14 > 0:11:18We can see that a family of badgers can have a really big territory
0:11:18 > 0:11:22and I want to find out how they use all of that space.
0:11:23 > 0:11:27Badger expert Dr Chris Cheeseman has been watching badgers
0:11:27 > 0:11:31for over 35 years, so he knows a lot about them.
0:11:31 > 0:11:34He's found the entrance to what is known as the main sett.
0:11:36 > 0:11:39- That's quite busy, Chris. - Yeah, this is an active hole.
0:11:39 > 0:11:43Some bedding here, that's just been taken down.
0:11:43 > 0:11:45Some fresh hairs, a few prints.
0:11:45 > 0:11:47This sett looks like it's been here a long time.
0:11:47 > 0:11:49Yes, it's a well-established sett.
0:11:49 > 0:11:52I would say that this is part of the landscape,
0:11:52 > 0:11:54it's a good main sett, sort of, situation.
0:11:54 > 0:11:58We call this the main sett because badgers have more than one sett.
0:11:58 > 0:12:01Badgers like to live in the main sett for most of the year.
0:12:01 > 0:12:05This is where they'll have their litter of babies.
0:12:05 > 0:12:08This main sett might have been here for hundreds of years.
0:12:08 > 0:12:12There are other setts as well, but they are all smaller.
0:12:12 > 0:12:15They're like a second home for the badgers.
0:12:15 > 0:12:17We're going to see if we can find one.
0:12:19 > 0:12:22This is still a badger sett, and we're about, well,
0:12:22 > 0:12:25a few hundred metres from the main sett here.
0:12:25 > 0:12:27This is what we call an outlying sett,
0:12:27 > 0:12:30as opposed to that big headquarters, the main sett.
0:12:31 > 0:12:35The badgers use the small setts in the spring, summer and autumn,
0:12:35 > 0:12:37when there's lots of food around.
0:12:37 > 0:12:39They can go out to find their dinner
0:12:39 > 0:12:42and then pop into one of the smaller setts for a little rest.
0:12:44 > 0:12:46So the small setts are really useful.
0:12:46 > 0:12:49There might be up to six in each badger territory.
0:12:51 > 0:12:54Badgers are really smart to have their main home
0:12:54 > 0:12:56and a few other homes as well.
0:12:56 > 0:12:57Wouldn't that be nice?
0:13:01 > 0:13:05Badgers are really good at knowing which territory is theirs
0:13:05 > 0:13:07and what belongs to other families.
0:13:07 > 0:13:10Let's take a closer look at the badger territory
0:13:10 > 0:13:13that I've been exploring.
0:13:13 > 0:13:15I love a map, and here's a map which identifies
0:13:15 > 0:13:19all of the significant features of our badger's social group.
0:13:20 > 0:13:22Firstly, the main sett, it's here,
0:13:22 > 0:13:25pretty much in the centre of their territory.
0:13:25 > 0:13:29The other red spots here identify the sub setts.
0:13:29 > 0:13:33These closer to the edge, well, these are useful boltholes.
0:13:33 > 0:13:36In the past, when there were predators, the badgers would have
0:13:36 > 0:13:40needed to have nipped into those, perhaps, if they were under attack.
0:13:40 > 0:13:43Badgers usually stay in their own land.
0:13:43 > 0:13:45If they go into territories where other badgers live,
0:13:45 > 0:13:47they might be chased out.
0:13:47 > 0:13:51It might sound a bit strange but badgers know which bit of land
0:13:51 > 0:13:54is theirs and which bit belongs to other badgers.
0:13:54 > 0:13:59They know this by their toilets, which are known as latrines.
0:13:59 > 0:14:02Badgers have really distinct smelling poo,
0:14:02 > 0:14:04which they put at the edge of their territories,
0:14:04 > 0:14:07so other badgers know they shouldn't enter.
0:14:07 > 0:14:11It's all very carefully planned, as you can see from my map.
0:14:12 > 0:14:14And around the edge of that,
0:14:14 > 0:14:16to mark it very clearly for all of the badgers,
0:14:16 > 0:14:19are the territorial latrines,
0:14:19 > 0:14:21which I've marked here in blue.
0:14:21 > 0:14:25So as you can see, rather than being a random collection of holes
0:14:25 > 0:14:28placed in a wood somewhere, this system of setts,
0:14:28 > 0:14:30and their placement within the territory,
0:14:30 > 0:14:32is actually quite sophisticated
0:14:32 > 0:14:35and it's essential to the survival of these animals.
0:14:48 > 0:14:51Badgers are very social animals.
0:14:51 > 0:14:55They like to live with each other in homes known as setts.
0:14:55 > 0:14:58Inside their burrows, all the badgers know their place
0:14:58 > 0:15:01and where they belong in the group.
0:15:01 > 0:15:04This is a sett we built especially to be as close
0:15:04 > 0:15:05to nature as possible.
0:15:05 > 0:15:08It means we can study and film badgers behaving like they
0:15:08 > 0:15:13would in the wild and it's great to be able to watch them this close up.
0:15:14 > 0:15:17It strikes me that if our young badgers aren't eating,
0:15:17 > 0:15:19and they're not sleeping and they're not playing,
0:15:19 > 0:15:21then what they're doing is grooming.
0:15:21 > 0:15:23They spend a lot of time on their personal hygiene
0:15:23 > 0:15:25and, of course, grooming one another.
0:15:28 > 0:15:30Badgers obviously like to keep clean.
0:15:31 > 0:15:34This is just how badgers behave in the wild as well.
0:15:34 > 0:15:38Sometimes they will scratch for up to ten minutes.
0:15:38 > 0:15:41A bit like us coming in after a hot, sweaty day,
0:15:41 > 0:15:44getting into the shower and scrubbing furiously,
0:15:44 > 0:15:46and there's a real sense of joy about it, as well.
0:15:48 > 0:15:51There's a very good reason why badgers like to keep clean.
0:15:51 > 0:15:54Lots of tiny insects like to live on badgers,
0:15:54 > 0:15:57because their fur is cosy and warm.
0:15:57 > 0:16:02There are even little insects called fleas that feed on badger blood.
0:16:02 > 0:16:05So it isn't really surprising that badgers spend
0:16:05 > 0:16:08so much time grooming or cleaning themselves and each other.
0:16:09 > 0:16:13How would you like to be covered in blood sucking fleas?
0:16:16 > 0:16:20Chris Cheeseman has been studying badgers for over 35 years,
0:16:20 > 0:16:23so he knows lots about them and why fleas like them so much.
0:16:24 > 0:16:29Fleas need a badger to suck blood from, get a blood meal,
0:16:29 > 0:16:32and they also need somewhere to lay their eggs.
0:16:32 > 0:16:35They don't do it on the badger, they do it in the badger's nest.
0:16:35 > 0:16:37The eggs will hatch out in the bedding,
0:16:37 > 0:16:39the larvae will develop there.
0:16:39 > 0:16:42When they hatch into fleas, eventually,
0:16:42 > 0:16:45off they go again, find an adult badger to suck blood from.
0:16:45 > 0:16:48That's the life cycle, basically.
0:16:48 > 0:16:51That means that the badger's bedding is full of fleas,
0:16:51 > 0:16:53and that it's really uncomfortable for them.
0:16:53 > 0:16:57To get around this, the badgers like to change their bedding all of the time.
0:16:58 > 0:17:02Badgers have the habit of collecting bedding
0:17:02 > 0:17:07from any sort of bedding, like straw, hay, dead leaves.
0:17:07 > 0:17:09They bring that into the nest chamber
0:17:09 > 0:17:13and, after a while, it does get infested
0:17:13 > 0:17:16and the badger will take it back out
0:17:16 > 0:17:18and they do scatter it quite well.
0:17:18 > 0:17:21Now, when it's out there, exposed to sunlight...
0:17:21 > 0:17:25- That's going to kill the larvae. - It's going to kill the larvae and it's going to make it hard
0:17:25 > 0:17:29for the fleas to survive. So it's a good way of keeping that parasite burden down,
0:17:29 > 0:17:32to take your bedding out and air it.
0:17:32 > 0:17:35So badgers are really wise to air their bedding
0:17:35 > 0:17:38and also very clever about what they choose to make their beds from
0:17:38 > 0:17:41in the first place.
0:17:41 > 0:17:44It's really interesting that badgers like to use
0:17:44 > 0:17:47all different types of plants for their bedding.
0:17:47 > 0:17:49They do bring in fresh, green bedding.
0:17:49 > 0:17:53I've seen them dragging in lots of fresh green bracken,
0:17:53 > 0:17:55and other plants are often brought into the nest, aren't they?
0:17:55 > 0:17:58Well, one that's frequently brought in, and it really is smelly,
0:17:58 > 0:18:00is garlic. Wild garlic.
0:18:00 > 0:18:05- They'll bring in huge quantities of fresh, green garlic leaves.- Mm.
0:18:05 > 0:18:07I'm sure the fleas don't particularly like that,
0:18:07 > 0:18:11so, maybe, garlic helps keep fleas, ticks
0:18:11 > 0:18:14and lice away from the bedding.
0:18:14 > 0:18:17So badgers use lots of types of bedding for different reasons,
0:18:17 > 0:18:21and they're clever enough to know that smelly plants like garlic
0:18:21 > 0:18:23help to keep the fleas away.
0:18:23 > 0:18:27It's their very own natural insect repellent.
0:18:43 > 0:18:47One burrower, the most secret of them all,
0:18:47 > 0:18:51spends almost all of its time living alone.
0:18:51 > 0:18:52The mole.
0:18:54 > 0:18:56Moles live underground all of the time.
0:18:56 > 0:18:59They never leave their burrows.
0:18:59 > 0:19:01We've built a special burrow
0:19:01 > 0:19:03so we can study how moles live underground.
0:19:05 > 0:19:08Their bodies are really good for living underground,
0:19:08 > 0:19:12where there's not much air, because even though they're really active
0:19:12 > 0:19:16and do lots of digging, they need much less oxygen than human beings.
0:19:16 > 0:19:21There's no light underground, and the moles have bad eyesight.
0:19:21 > 0:19:24But over millions of years moles' bodies have adapted
0:19:24 > 0:19:27and changed to help them live underground.
0:19:28 > 0:19:31So even though they can't see very well
0:19:31 > 0:19:34the moles make up for it with their noses.
0:19:34 > 0:19:37A mole's nose has a special bit for feeling.
0:19:39 > 0:19:42It's called the Eimer's organ.
0:19:42 > 0:19:44It's made up of special parts
0:19:44 > 0:19:48that let the moles feel every bit of their burrow.
0:19:48 > 0:19:51Moles feel with their tails as well.
0:19:51 > 0:19:54Of course, that's really important, as they're almost
0:19:54 > 0:19:57blind in this totally dark place.
0:19:57 > 0:20:00You can see here what looks like an extra finger,
0:20:00 > 0:20:02although it isn't, really.
0:20:04 > 0:20:09Look closer and that sixth finger is actually a type of thumb.
0:20:09 > 0:20:14Moles use their wide hands as if they were a specially made spade.
0:20:14 > 0:20:17This is another example of how moles' bodies have adapted
0:20:17 > 0:20:20and changed to make their lives underground easier.
0:20:21 > 0:20:24The mole uses its burrow to catch earthworms.
0:20:24 > 0:20:28It likes to bite off their heads so they can't move
0:20:28 > 0:20:32and then the mole can come back when it's hungry and eat them later.
0:20:32 > 0:20:36As the mole digs through the soil they seem to move really easily.
0:20:38 > 0:20:40How they dig looks familiar.
0:20:40 > 0:20:42It makes me think of another animal.
0:20:50 > 0:20:55This is Starburst and her sisters and they are common seals,
0:20:55 > 0:20:58and you might think I've gone a bit mad looking at seals,
0:20:58 > 0:21:00when I'm talking about moles,
0:21:00 > 0:21:03but there are some parallels between these species.
0:21:03 > 0:21:07And one is that they both live in a 3-D environment.
0:21:07 > 0:21:11The moles are living surrounded by soil
0:21:11 > 0:21:13and these things are surrounded by water.
0:21:13 > 0:21:18Where the animals live has changed the way they move.
0:21:18 > 0:21:20This is because of their anatomy,
0:21:20 > 0:21:23that's the way their bodies are designed.
0:21:23 > 0:21:27So I want to know how a mole's body compares to a seal's.
0:21:27 > 0:21:29Come on.
0:21:33 > 0:21:37For a start, seals have very streamlined bodies
0:21:37 > 0:21:41for slipping easily and gracefully through the water,
0:21:41 > 0:21:43just as moles have streamlined bodies
0:21:43 > 0:21:46for pushing their way through the soil.
0:21:46 > 0:21:49Now, these animals don't have their limbs beneath their body
0:21:49 > 0:21:51to support their weight,
0:21:51 > 0:21:55because for seals the water is supporting that body weight.
0:21:55 > 0:21:58And they have their forelimbs on the side of their body,
0:21:58 > 0:22:00just like moles do.
0:22:03 > 0:22:07And moles and seals have even more in common.
0:22:07 > 0:22:11We can learn about this by looking at skeletons, or bones,
0:22:11 > 0:22:13of both animals.
0:22:13 > 0:22:16This is Peter Stafford, who knows a lot about moles.
0:22:16 > 0:22:19What have we got here then, Peter? Looks like a seal skeleton
0:22:19 > 0:22:22and a mole skeleton for a bit of comparative anatomy to me.
0:22:22 > 0:22:24Yeah, you're spot on, Chris, that's exactly what it is.
0:22:24 > 0:22:26Let's start at the back end, then, the tail,
0:22:26 > 0:22:29because in both animals it's very short, isn't it?
0:22:29 > 0:22:32Yes, compared with the overall size of the body,
0:22:32 > 0:22:34it is, indeed, very short,
0:22:34 > 0:22:37and would serve very little obvious function in its normal daily life.
0:22:39 > 0:22:42Looking at the skeleton of both, very streamlined,
0:22:42 > 0:22:44this one for slipping through water
0:22:44 > 0:22:47- and this one for pushing through soil, of course.- Yes, indeed.
0:22:47 > 0:22:51Very streamlined, and there is this particular similarity,
0:22:51 > 0:22:54which I've always said that moles tend to swim through the soil
0:22:54 > 0:22:57rather than burrow, or dig, through it.
0:22:57 > 0:23:01They do this through the soil rather than what we perceive as burrowing.
0:23:04 > 0:23:07The seal here has got its hands, if you like,
0:23:07 > 0:23:11which have evolved into these large paddles for pushing itself
0:23:11 > 0:23:14through the water, and the mole, well, has no parallel, does it?
0:23:14 > 0:23:18No, I mean, they're spades, aren't they? Well, they're shovels!
0:23:18 > 0:23:21So, here we are then, this is an animal that swims through the sea
0:23:21 > 0:23:25and here we have an animal which, through similar adaptations,
0:23:25 > 0:23:27- swims through the soil. - That's exactly what they both do.
0:23:29 > 0:23:33So even though moles and seals are very different animals,
0:23:33 > 0:23:35they do have a lot in common.
0:23:35 > 0:23:38Their bodies help to make digging and swimming easier.
0:23:38 > 0:23:41Even though they're completely different to look at,
0:23:41 > 0:23:43they move in a similar way.
0:23:58 > 0:24:02Water voles are one of Britain's rarest burrowers.
0:24:02 > 0:24:05They're an endangered species and there aren't many of them
0:24:05 > 0:24:07left in the United Kingdom.
0:24:07 > 0:24:09You might know them from the famous children's book
0:24:09 > 0:24:11Wind In The Willows.
0:24:11 > 0:24:14The main character, Ratty, was actually a water vole
0:24:14 > 0:24:16and not a rat at all.
0:24:16 > 0:24:20We built a special burrow so we can study and film water voles.
0:24:22 > 0:24:25Burrowing animals have a lot of things in common,
0:24:25 > 0:24:27but one thing that makes water voles different
0:24:27 > 0:24:30is that, as well as living underground,
0:24:30 > 0:24:32they like to be...
0:24:32 > 0:24:34in the water.
0:24:34 > 0:24:38Water voles live alongside each other in burrows
0:24:38 > 0:24:40made in the side of rivers.
0:24:40 > 0:24:44Around their burrows is the land and water called their territory.
0:24:46 > 0:24:49Stretching down this lovely river in Devon
0:24:49 > 0:24:51are a whole lot of water vole territories,
0:24:51 > 0:24:55which means that their burrow system will be running
0:24:55 > 0:24:58for hundreds of metres up and down these banks,
0:24:58 > 0:25:01and we can see some of the tunnels that have been exposed here.
0:25:01 > 0:25:06These tunnels will go right into the bank, as far as six metres,
0:25:06 > 0:25:09and sometimes, when there's lots of predators,
0:25:09 > 0:25:11things like stoats and weasels,
0:25:11 > 0:25:15they'll even make amends for that by making special shaped tunnels.
0:25:15 > 0:25:18Some will go in beneath the water surface,
0:25:18 > 0:25:21making their life difficult, others, above the surface
0:25:21 > 0:25:24but then with a U-bend, which floods full of water,
0:25:24 > 0:25:27so those stoats and weasels can't get through it
0:25:27 > 0:25:28and the voles remain safe.
0:25:28 > 0:25:32Water voles like the river as it gives them
0:25:32 > 0:25:33everything they need to survive.
0:25:33 > 0:25:36The banks give them a nice spot for a home,
0:25:36 > 0:25:39and they can also use the river to find food.
0:25:44 > 0:25:47Of course, because they live by a river,
0:25:47 > 0:25:49water voles need to be strong swimmers,
0:25:49 > 0:25:53and baby water voles have to learn to swim, just like the rest of us.
0:25:55 > 0:25:57Water vole babies are called pups.
0:25:57 > 0:25:59They're born underground.
0:25:59 > 0:26:02They don't go outside until they're 14 days old.
0:26:12 > 0:26:15Swimming lessons can get off to a slow start.
0:26:15 > 0:26:19The water voles might be nervous and stay by the water's edge...
0:26:21 > 0:26:23..but not for long.
0:26:23 > 0:26:26Very soon they'll be strong, confident swimmers,
0:26:26 > 0:26:28just like their mums and dads.
0:26:32 > 0:26:36It's no wonder that baby water voles are so good at swimming.
0:26:36 > 0:26:38Their bodies are made for water.
0:26:38 > 0:26:41They have waterproof fur, which means that even if they get
0:26:41 > 0:26:45their heads wet, they can usually dry them off with a single shake.
0:26:46 > 0:26:50Water voles are an example of an aquatic mammal.
0:26:50 > 0:26:52These are animals that can swim.
0:26:52 > 0:26:57But there is something about the vole's feet that's unusual.
0:26:57 > 0:26:59I've got a great view of his feet here.
0:27:00 > 0:27:03For an aquatic mammal, you'd expect webbing.
0:27:03 > 0:27:08Beavers, otters, they both have webbed feet. But water voles don't.
0:27:08 > 0:27:12In fact, you can see these voles have gaps between their toes,
0:27:12 > 0:27:14and I'm really surprised by that.
0:27:18 > 0:27:21It's really lucky for voles that they're good swimmers,
0:27:21 > 0:27:23as they often have to get away from predators in the water
0:27:23 > 0:27:25and on the land.
0:27:27 > 0:27:31One of the main enemies of the vole is the American mink.
0:27:34 > 0:27:37These animals were brought over to the UK in the 1930s
0:27:37 > 0:27:40and the water voles have no way of hiding from them.
0:27:42 > 0:27:44When water voles are above ground,
0:27:44 > 0:27:47they do their best to stay out of sight.
0:27:47 > 0:27:50So they make little covered passageways in the undergrowth,
0:27:50 > 0:27:51called runs.
0:27:51 > 0:27:54These lead from their burrows to the water
0:27:54 > 0:27:57and they're also great hiding places.
0:27:57 > 0:28:01In here is a run that's been made through
0:28:01 > 0:28:03some of the tussocks in the grass by the water voles.
0:28:03 > 0:28:07They've come up the bank, where I can see that there's some bare mud,
0:28:07 > 0:28:09they've been frequent in their visits,
0:28:09 > 0:28:12but, look here, if I part the grass,
0:28:12 > 0:28:14you can see that between the tussocks
0:28:14 > 0:28:17there's a neat little covered run.
0:28:17 > 0:28:20Because it's covered with all of this grass,
0:28:20 > 0:28:24it's offering them protection from predators, they can't be seen.
0:28:25 > 0:28:27And, as the water voles can't be seen,
0:28:27 > 0:28:30it means that they can hide important things here,
0:28:30 > 0:28:33like their favourite foods.
0:28:33 > 0:28:35Oh, look at this!
0:28:35 > 0:28:38Down in here looks like...
0:28:38 > 0:28:41..water crowfoot, or something like that,
0:28:41 > 0:28:43and they've snipped it off into these packages,
0:28:43 > 0:28:46something that they can carry very easily,
0:28:46 > 0:28:50and then moved it here to the security of this tunnel,
0:28:50 > 0:28:52so that they can eat it without the risk of being spotted
0:28:52 > 0:28:55by anything that wants to eat them.
0:28:55 > 0:28:58That's like a little water vole breakfast bar down there.
0:29:01 > 0:29:03So if you want to see a water vole in the wild,
0:29:03 > 0:29:07the best thing to do would be to go and have a look near a river bank.
0:29:07 > 0:29:10You may not be able to see them swimming,
0:29:10 > 0:29:12but you might see the entrance to their home.
0:29:16 > 0:29:18Make sure you take an adult with you,
0:29:18 > 0:29:20and don't go too close to the edge of the water.
0:29:20 > 0:29:23And, remember, be very, very quiet.
0:29:27 > 0:29:30Our special filming in the burrows that we made
0:29:30 > 0:29:34for all of our animals has shown us some really interesting things.
0:29:34 > 0:29:37But, you know, one thing that it's made me realise
0:29:37 > 0:29:41is just how little we know about these animals' lives.
0:29:41 > 0:29:45The lives that are happening just here beneath our feet.
0:29:45 > 0:29:48But at least we've revealed some of their secrets,
0:29:48 > 0:29:52some of their beauty, and some of their wonder.
0:30:01 > 0:30:04Subtitles by Red Bee Media Ltd