0:00:00 > 0:00:05- Rural Wales offers some of the most - spectacular sights in Britain.
0:00:08 > 0:00:12- But the countryside - offers much more than just views.
0:00:12 > 0:00:15- It's home - to some our best-loved wildlife.
0:00:16 > 0:00:20- But one group of mammals - is living a secret life.
0:00:22 > 0:00:25- By burrowing tunnels - miles underground...
0:00:25 > 0:00:30- ..the way these animals live - their lives beneath the surface...
0:00:30 > 0:00:34- ..has been a mystery until now.
0:00:35 > 0:00:39- We're going to do something - that's never been done before.
0:00:39 > 0:00:44- By uncovering some of these - burrowers' tunnels and chambers...
0:00:44 > 0:00:48- ..we're going to recreate - an artificial habitat.
0:00:48 > 0:00:50- For the first time ever...
0:00:51 > 0:00:55- ..we'll get an insight - into their secret lives underground.
0:00:57 > 0:01:01- We'll discover what water voles - do all day in their tunnels...
0:01:02 > 0:01:07- ..how rabbits cope with nurturing - dozens of offspring each year...
0:01:07 > 0:01:10- ..and how small badgers - learn to cope...
0:01:10 > 0:01:13- ..with the big world - beyond the sett.
0:01:13 > 0:01:17- Join me, Iolo Williams, - as we venture...
0:01:17 > 0:01:21- ..to the magical, hidden, - subterranean world of the burrowers.
0:01:22 > 0:01:24- Subtitles
0:01:46 > 0:01:51- So far, we've discovered the size - and scale of a rabbit warren...
0:01:51 > 0:01:54- ..a water vole's den - and a badger sett.
0:01:55 > 0:01:59- Work on the artificial - tunnels and chambers is ongoing.
0:01:59 > 0:02:02- But the rabbit warren is complete.
0:02:02 > 0:02:04- The rabbits have settled in...
0:02:04 > 0:02:08- ..and are beginning to reveal - their underground secrets.
0:02:10 > 0:02:15- The impression you get about life - in a rabbit warren in winter...
0:02:15 > 0:02:19- ..is of animals hanging around, - foraging and relaxing.
0:02:20 > 0:02:22- That might be the case - for only a short time.
0:02:23 > 0:02:25- Things change in the New Year.
0:02:25 > 0:02:29- The reason for that change - is hormones.
0:02:33 > 0:02:38- This is revealed when two male - rabbits begin to fight each other.
0:02:39 > 0:02:43- That's why partially-tamed rabbits - are used in our artificial warren.
0:02:44 > 0:02:48- Wild rabbits might not only feel - uncomfortable in a fake warren...
0:02:49 > 0:02:52- ..they could possibly - end up killing each other.
0:02:56 > 0:02:59- The strongest buck - chases the other out of the warren.
0:03:00 > 0:03:04- The strongest male - mates with each of the females...
0:03:04 > 0:03:07- ..and eradicates the competition.
0:03:07 > 0:03:10- Life isn't any easier for the does.
0:03:10 > 0:03:15- They are under pressure, but why? - What happens next is a clue.
0:03:15 > 0:03:18- This is very interesting.
0:03:18 > 0:03:22- The doe is urinating - and marking her territory.
0:03:23 > 0:03:25- We're seeing her do it underground.
0:03:25 > 0:03:30- We see them do it above ground, so - why do they do it underground too?
0:03:30 > 0:03:33- It's pitch black in the warren...
0:03:33 > 0:03:37- ..and they need to know - who owns which chamber and so on.
0:03:37 > 0:03:42- The female rabbit, - the queen bee, if you like...
0:03:43 > 0:03:47- ..has chosen - the best chamber in the warren.
0:03:47 > 0:03:49- She's marking her territory.
0:03:49 > 0:03:51- She's marking her territory.- - What does she do with the chamber?
0:03:52 > 0:03:56- I can see her carrying straw, - so is she preparing for birth?
0:03:56 > 0:03:58- Yes, she's preparing the nest.
0:03:58 > 0:04:01- Once she's ready to give birth...
0:04:01 > 0:04:05- ..she'll pluck the fur - from her own skin...
0:04:05 > 0:04:07- ..to prepare a warm nest.
0:04:07 > 0:04:10- It must be very warm in there...
0:04:10 > 0:04:14- ..with a combination - of straw and fur, and here she is.
0:04:15 > 0:04:17- She's starting with the straw.
0:04:27 > 0:04:32- Remember the last time I was here - with the water voles?
0:04:32 > 0:04:37- It was the beginning of the project - and only the framework was in place.
0:04:37 > 0:04:42- It's been completely transformed - from all the concrete and twigs.
0:04:42 > 0:04:45- They've a place to swim, - a food supply...
0:04:45 > 0:04:47- ..and somewhere to shelter.
0:04:47 > 0:04:50- They appear to be very happy - in their new home.
0:04:53 > 0:04:57- The tunnels and chambers - follow the same pattern...
0:04:57 > 0:05:01- ..as the burrows they - made previously in the sand box.
0:05:01 > 0:05:05- Built on this foundation, the ideal - artificial habitat has been created.
0:05:06 > 0:05:11- So far, a pair of water voles - have settled into their new home.
0:05:14 > 0:05:17- If I start from the top - and work my way down...
0:05:17 > 0:05:20- ..there's a nest here - and another over there.
0:05:20 > 0:05:23- The level of the water - on this side is very low.
0:05:23 > 0:05:27- But in the wild, - the level rises after it rains.
0:05:27 > 0:05:32- What they don't want is for - the nest and their young to drown.
0:05:32 > 0:05:35- These are - as high as they can possibly be.
0:05:35 > 0:05:41- Moving down, this small chamber here - is where they leave their droppings.
0:05:41 > 0:05:46- That one is far enough away from - the nest so that they don't soil it.
0:05:46 > 0:05:50- Right at the bottom, you'll notice - that there are tunnels...
0:05:51 > 0:05:55- ..going from that channel - and that channel...
0:05:55 > 0:06:01- ..out to the stream itself where the - animals spend most of their time.
0:06:02 > 0:06:07- These two are under pressure to - demonstrate what water voles do...
0:06:07 > 0:06:10- ..in their underground dens.
0:06:10 > 0:06:13- With a bit of luck, they'll breed.
0:06:13 > 0:06:17- If that happens, the young will - also be released into the wild...
0:06:18 > 0:06:22- ..to an appropriate territory in - order to protect this rare species.
0:06:23 > 0:06:25- But it doesn't look - too hopeful so far...
0:06:26 > 0:06:29- ..because the two - are fighting regularly.
0:06:29 > 0:06:33- It's obvious that the light brown - female is the boss.
0:06:39 > 0:06:41- This is interesting, Dyfrig...
0:06:41 > 0:06:45- ..because they've just been - introduced to their new home...
0:06:45 > 0:06:48- ..and they're fighting ferociously.
0:06:48 > 0:06:54- No matter if they're - two females or two males...
0:06:54 > 0:06:57- ..they have to - establish their own territory.
0:06:58 > 0:07:03- They ferociously defend - the best areas...
0:07:03 > 0:07:06- ..where there's - a good supply of food...
0:07:07 > 0:07:11- ..and a wide variety of ideal - nesting areas within their habitat.
0:07:11 > 0:07:15- Whether they're two males - or two females...
0:07:15 > 0:07:18- ..they're establishing - who's the boss.
0:07:18 > 0:07:23- Small mammals like these - are constantly feeding.
0:07:26 > 0:07:29- When a pattern is established, - they settle down.
0:07:30 > 0:07:33- These two have segregated their home - into two areas...
0:07:34 > 0:07:38- ..with the female's chambers on the - left and the male's on the right.
0:07:39 > 0:07:43- There's no chance of them mating - if they continue like this.
0:07:55 > 0:07:59- At the Secret World - rescue centre in Somerset...
0:08:00 > 0:08:02- ..the big day has arrived.
0:08:03 > 0:08:05- The badgers' new home is ready.
0:08:05 > 0:08:09- Having been raised in a kitchen - for the past six weeks...
0:08:09 > 0:08:13- ..the six orphaned badgers - can move into their new home.
0:08:14 > 0:08:17- This is where they'll live - for the next three months.
0:08:19 > 0:08:23- Take a look at this - - the artificial badger's sett.
0:08:23 > 0:08:27- You can see - a badger scurrying about up there.
0:08:27 > 0:08:32- This is the first time I've seen - badgers underground like this.
0:08:32 > 0:08:37- It's artificial but they've tried - to make it as authentic as possible.
0:08:37 > 0:08:40- You can see - three or four badgers up there...
0:08:41 > 0:08:43- ..in what I assume - is the sleeping chamber.
0:08:44 > 0:08:47- There are at least - three or four animals there.
0:08:47 > 0:08:51- There are four chambers in all - with tunnels beyond the wall...
0:08:51 > 0:08:56- ..that are interconnected, enabling - the badgers to venture outside.
0:08:57 > 0:09:01- This is fantastic - they've - created the roots of a tree...
0:09:01 > 0:09:06- ..and provided pieces of wood - for them to sharpen teeth and play.
0:09:06 > 0:09:12- The fact they've tried to make it - as natural as possible is important.
0:09:12 > 0:09:16- The framework - follows what Rhys and I learnt...
0:09:16 > 0:09:20- ..from studying a badger's sett - in the forest during winter.
0:09:20 > 0:09:23- Sizable chambers that allow them...
0:09:23 > 0:09:27- ..to familiarize themselves - with one another.
0:09:27 > 0:09:32- Badgers spend the first three months - of their lives underground...
0:09:32 > 0:09:35- ..without venturing to the surface.
0:09:35 > 0:09:38- Nobody has ever seen - young badgers like these...
0:09:39 > 0:09:42- ..during - this crucial time in their lives.
0:09:44 > 0:09:46- It soon becomes apparent...
0:09:47 > 0:09:50- ..that the badgers - have taken to their new home.
0:09:50 > 0:09:54- They are eager to explore - every nook and cranny.
0:09:54 > 0:09:57- Though badgers have poor eyesight...
0:09:57 > 0:10:00- ..their sense of smell - is much better than ours.
0:10:01 > 0:10:04- One of the cubs - creates a nest straightaway...
0:10:04 > 0:10:07- ..by moving and carrying nesting - material around the chamber.
0:10:08 > 0:10:13- He does this in exactly the same way - as adult badgers do above ground.
0:10:14 > 0:10:17- This teaches us that cubs - don't rely on their parents...
0:10:18 > 0:10:21- ..to create a nest - and a bed for them to keep warm.
0:10:21 > 0:10:24- The information is inherent.
0:10:26 > 0:10:30- Two of the badgers are fighting...
0:10:30 > 0:10:33- ..and that's going to be important - for them later on.
0:10:34 > 0:10:36- They're working out - who's the strongest.
0:10:36 > 0:10:40- When they're older, they might - have to defend their territory.
0:10:41 > 0:10:43- There are six badgers in all.
0:10:43 > 0:10:48- Five of them are inside and - the other is in a different hole.
0:10:48 > 0:10:52- The six have come from - all over the country.
0:10:52 > 0:10:54- Two have come from Wales.
0:10:54 > 0:10:57- They're usually found - by dog walkers.
0:10:58 > 0:11:01- Often the mother has been killed.
0:11:01 > 0:11:06- We see plenty of badgers - knocked down by cars on the roads.
0:11:06 > 0:11:09- They're brought to Secret World...
0:11:09 > 0:11:13- ..with the eventual aim - of reintroducing them into the wild.
0:11:13 > 0:11:17- They keep them - in an artificial sett like this.
0:11:17 > 0:11:20- They make sure - there's a family of them.
0:11:20 > 0:11:24- They're reintroduced into the wild - in a suitable place...
0:11:24 > 0:11:27- ..to ensure - they have the best start...
0:11:27 > 0:11:32- ..and are able to survive - their new life in the countryside.
0:11:36 > 0:11:37- .
0:11:40 > 0:11:40- Subtitles
0:11:40 > 0:11:42- Subtitles- - Subtitles
0:11:48 > 0:11:50- Here in the Dolgellau area...
0:11:51 > 0:11:54- ..Rhys and I - have been studying badgers.
0:11:54 > 0:11:59- In the previous episode, we placed - red plastic pellets in their food...
0:11:59 > 0:12:01- ..to establish - the scale of their territory.
0:12:02 > 0:12:06- I don't know - how old these droppings are...
0:12:06 > 0:12:10- ..but you can see - red pellets in amongst them...
0:12:10 > 0:12:14- ..which indicates that this is - part of their territory.
0:12:14 > 0:12:17- These are probably - one or two days old.
0:12:17 > 0:12:21- There are more nearby, - and this is often the case.
0:12:21 > 0:12:24- They're - in close proximity to each other.
0:12:24 > 0:12:27- Some of the burrows - are substantial...
0:12:27 > 0:12:32- ..especially those dotted around - the fringes of the territory.
0:12:32 > 0:12:34- From what I've seen...
0:12:34 > 0:12:39- ..they're situated close to - a natural, or unnatural, boundary.
0:12:40 > 0:12:42- A stone wall, a stream, - a path or a fence.
0:12:43 > 0:12:45- Yes, you see that often.
0:12:45 > 0:12:47- Within the territory...
0:12:48 > 0:12:50- ..you see the same sort of pattern.
0:12:50 > 0:12:54- There's a burrow in the woods - near a fence where badgers roam.
0:12:54 > 0:12:58- I know they're badgers - because there are old tracks there.
0:12:58 > 0:13:01- They've been there - for such a long time...
0:13:01 > 0:13:05- ..it's possible - to get an aerial view of them.
0:13:05 > 0:13:08- Often you find - their fur snagged on barbed wire.
0:13:08 > 0:13:12- Badger fur is distinctive - and found near those places...
0:13:13 > 0:13:15- ..which cross - a boundary of some kind.
0:13:16 > 0:13:19- Often you notice their fur - in those locations.
0:13:20 > 0:13:23- The red plastic pellets - can be seen in the faeces.
0:13:23 > 0:13:27- They've caused no harm at all - to the badger.
0:13:27 > 0:13:30- It demonstrates - that the science works.
0:13:31 > 0:13:35- That there's a means of establishing - the nature of their territory.
0:13:36 > 0:13:39- If you wanted - to take this a bit further...
0:13:39 > 0:13:44- ..you'd go to the nearest burrow - and leave other coloured pellets...
0:13:44 > 0:13:47- ..to build some sort of a picture...
0:13:47 > 0:13:50- ..and determine their territory.
0:13:50 > 0:13:52- You can map an entire area.
0:13:52 > 0:13:57- It's a very interesting study, - even in an area such as this.
0:14:06 > 0:14:10- Back at Secret World, - it becomes obvious...
0:14:10 > 0:14:12- ..that there's a problem.
0:14:13 > 0:14:17- Five of the badgers are living - in harmony and sharing the chambers.
0:14:18 > 0:14:21- But one of the cubs is absent.
0:14:21 > 0:14:25- This is the smallest cub, - and the last to be rescued.
0:14:25 > 0:14:29- She spends most of her time hiding - in one of the other chambers.
0:14:29 > 0:14:33- It's a short season - before the first winter arrives...
0:14:33 > 0:14:36- ..so they must - quickly learn to feed...
0:14:36 > 0:14:41- ..and co-exist with other badgers - to protect themselves.
0:14:42 > 0:14:46- This very small cub - is set apart from the others.
0:14:47 > 0:14:50- It's important for her - to become part of that group.
0:14:50 > 0:14:54- Definitely, - because naturally in the wild...
0:14:54 > 0:15:00- ..the number of offspring a female - produces is three at the most.
0:15:00 > 0:15:03- Often, the smallest of them...
0:15:04 > 0:15:07- ..doesn't survive.
0:15:10 > 0:15:13- For the smallest - to be able to survive...
0:15:13 > 0:15:16- ..she has to be part of the family.
0:15:16 > 0:15:19- If that happened in the wild, - she'd die.
0:15:19 > 0:15:21- Yes, she would.
0:15:21 > 0:15:24- If she doesn't - become part of the group...
0:15:24 > 0:15:28- ..she won't be released - into the wild.
0:15:28 > 0:15:31- No. She'd be doomed in the wild.
0:15:40 > 0:15:43- As winter turns to spring - in the countryside...
0:15:44 > 0:15:46- ..new life blossoms in the meadows.
0:15:48 > 0:15:51- I've come to the rabbit warren...
0:15:51 > 0:15:56- ..where they've found - quite a lot of rabbit fur.
0:15:56 > 0:16:00- Believe me, in rabbit terms, - that's a good sign.
0:16:00 > 0:16:02- Let's go inside.
0:16:06 > 0:16:09- Although it's difficult to see - what's happening...
0:16:09 > 0:16:11- ..a little nose provides a clue.
0:16:12 > 0:16:16- Five little rabbits have just - been born and they're miniscule.
0:16:20 > 0:16:25- It's odd that the mother comes in to - feed her young after giving birth...
0:16:25 > 0:16:27- ..and leaves right away.
0:16:27 > 0:16:30- She spends no time at all with them.
0:16:30 > 0:16:34- They spend around three minutes - a day with their young.
0:16:34 > 0:16:37- She quickly gives them milk...
0:16:37 > 0:16:40- ..so that - she can go out and feed herself.
0:16:40 > 0:16:44- She doesn't want to - draw attention to the nest.
0:16:44 > 0:16:47- She refrains - from going back and forth...
0:16:47 > 0:16:50- ..to avoid attracting predators.
0:16:53 > 0:16:58- A week later and the warren - is full of exciting developments.
0:16:58 > 0:17:00- Four nests are full of baby rabbits.
0:17:01 > 0:17:03- But the mothers rarely visit.
0:17:03 > 0:17:09- How do the young manage to survive - without their mother?
0:17:09 > 0:17:14- A thermal camera reveals many - interesting things about the nest.
0:17:16 > 0:17:19- If the mother spends - so much time away from the nest...
0:17:20 > 0:17:22- ..they must - eventually get very cold.
0:17:22 > 0:17:24- The nest keeps them warm.
0:17:24 > 0:17:29- The fur and the straw - keep them warm...
0:17:29 > 0:17:31- ..and also - they keep each other warm.
0:17:32 > 0:17:35- They sleep alongside each other.
0:17:36 > 0:17:38- When the kits - on the outside get cold...
0:17:38 > 0:17:42- ..they can scramble - into the middle to keep warm.
0:17:42 > 0:17:46- The warm kits from the centre - then move to the outside.
0:17:46 > 0:17:49- They move around quite a bit.
0:17:50 > 0:17:53- The thermal camera - suggests they're nice and warm.
0:17:54 > 0:17:56- The mother's returning.
0:17:56 > 0:17:59- So she's - only coming back to feed them?
0:17:59 > 0:18:01- That's right.
0:18:01 > 0:18:05- She's only there enough time to feed - them and she's straight back out.
0:18:05 > 0:18:08- They latch on straightaway, - don't they?
0:18:09 > 0:18:11- It's odd, isn't it?
0:18:11 > 0:18:13- They have no fur - and are unable to see.
0:18:14 > 0:18:16- If the mother hung around...
0:18:16 > 0:18:19- ..and attracted a predator...
0:18:19 > 0:18:22- ..they'd all be killed in a flash.
0:18:23 > 0:18:28- I was trying to understand why the - warren was such an ideal place...
0:18:28 > 0:18:31- ..to raise their young.
0:18:32 > 0:18:35- Even with - plummeting temperatures outside...
0:18:35 > 0:18:40- ..inside the warren, the young kits - are warm and comfortable.
0:18:51 > 0:18:55- Back to the water voles...
0:18:55 > 0:19:00- ..and the pair are making the most - of their new home, inside and out.
0:19:01 > 0:19:03- For the first time ever...
0:19:03 > 0:19:07- ..we're able to see how water voles - burrow to create tunnels.
0:19:09 > 0:19:13- They don't look equipped to do that, - just by looking at them.
0:19:13 > 0:19:15- Take the mole for instance.
0:19:16 > 0:19:19- Its front feet are like shovels. - It's able to burrow.
0:19:20 > 0:19:23- How on earth - can water voles do it so quickly?
0:19:24 > 0:19:27- With their teeth, predominantly.
0:19:27 > 0:19:29- The teeth are incredibly sharp.
0:19:30 > 0:19:32- They're out of proportion - to the head.
0:19:32 > 0:19:37- They're very big and prominent - at the front of the face...
0:19:37 > 0:19:39- ..beneath the nose.
0:19:40 > 0:19:44- They use - their front teeth to burrow...
0:19:44 > 0:19:47- ..and kick away - the earth with their back feet...
0:19:47 > 0:19:50- ..and flick it out of the hole.
0:19:51 > 0:19:55- They burrow into roots - which provide nourishment in winter.
0:19:55 > 0:19:59- They might be small - but they're powerful creatures.
0:20:00 > 0:20:03- I've been bitten by one - and it does hurt.
0:20:03 > 0:20:06- They cling on to you too, - don't they?
0:20:08 > 0:20:12- Inside the den, there is - still friction between them.
0:20:16 > 0:20:21- The whole process - of mating and breeding is...
0:20:26 > 0:20:30- How can I say it politely?
0:20:30 > 0:20:32- Ferocious.
0:20:32 > 0:20:33- Ferocious.- - Exactly.
0:20:33 > 0:20:35- A few days later...
0:20:36 > 0:20:39- ..and the pair finally get together.
0:20:40 > 0:20:43- Though things - are slow to begin with...
0:20:44 > 0:20:50- ..the pair eventually do - what we all hoped they would do.
0:21:05 > 0:21:10- In a short space of time, - we notice an important development.
0:21:10 > 0:21:15- They've blocked the entrances - to some of the tunnels, but why now?
0:21:15 > 0:21:19- Perhaps it's similar - to what they do in the wild?
0:21:19 > 0:21:24- They block the tunnels just before - or just after giving birth.
0:21:25 > 0:21:27- It's a possibility.
0:21:28 > 0:21:32- We can see them - building nests now, Dyfrig.
0:21:32 > 0:21:35- What materials do they use?
0:21:35 > 0:21:38- Any straw-like material...
0:21:39 > 0:21:41- ..which grows above ground.
0:21:44 > 0:21:49- Anything that would make - a comfortable nest underground.
0:21:49 > 0:21:53- As we see from this wall, - they have more than one nest.
0:21:54 > 0:21:55- Why's that?
0:21:56 > 0:21:59- They respond very well - to flood-like conditions.
0:22:00 > 0:22:04- As the water level rises, the main - chamber at the top, as it were...
0:22:04 > 0:22:08- ..is taken over by the female.
0:22:08 > 0:22:12- When the water level rises, - she moves to the highest chamber...
0:22:12 > 0:22:15- ..and takes her young with her.
0:22:16 > 0:22:20- When the water level drops, - she'll have more chance...
0:22:20 > 0:22:23- ..of recreating the nest lower down.
0:22:24 > 0:22:28- We'll have to wait - to see the new offspring...
0:22:28 > 0:22:31- ..but this gives us - a unique opportunity...
0:22:32 > 0:22:35- ..to see what happens - when these animals grow.
0:22:35 > 0:22:39- Nobody has had the opportunity - to do this before.
0:22:44 > 0:22:48- We've already learnt - how rabbits burrow...
0:22:49 > 0:22:51- ..how they prepare the warren...
0:22:52 > 0:22:54- ..and how they - use the chambers inside.
0:22:55 > 0:23:00- We've learnt that water voles - are incredibly neat animals...
0:23:00 > 0:23:04- ..and that - it's the females who dominate.
0:23:04 > 0:23:10- We've also learnt that badgers - rely on each other for survival.
0:23:10 > 0:23:13- Next time, - we'll discover how kits...
0:23:13 > 0:23:16- ..respond to multiple births.
0:23:17 > 0:23:20- We'll meet - the new-born water voles...
0:23:21 > 0:23:24- ..and introduce - another burrower to the series.
0:23:53 > 0:23:55- S4C Subtitles by Adnod Cyf.
0:23:55 > 0:23:56- .