Wild Isles Episode 4 Freshwater wildlife stories, filming locations and behind the scenes secrets

Here in Britain and Ireland, we have some of the loveliest rivers and lakes in the world. From the lochs of Scotland to the waterfalls of Wales. From the great Shannon River in Ireland, to small, intimate chalk streams. But today, less than half of our rivers and lakes are in good health for nature. In this episode we will reveal the crucial role that freshwater plays in supporting wildlife of all kinds.

Freshwater is the lifeblood of our wild isles. From highland burns in the Scottish Cairngorms to vast mudflats in Norfolk, Sir David Attenborough takes us on a journey from source to sea, following the course of our freshwater as it journeys through our landscapes.

Along the way we meet a host of wildlife that lives in, on and around our rivers, lakes, ponds and lochs, revealing the crucial role that water plays in supporting wildlife of all kinds. Determined Atlantic salmon battle their way upstream in one of the greatest migrations on the planet, beavers slow the flow with their expert dam-building, spiders become deadly assassins, millions of mayfly have mere days to live, and in shocking new behaviour caught on camera, an unlucky raft of young toadlets has to cross a 'killing zone' patrolled by carnivorous leeches...a tiny toad's worst nightmare.

As our rivers slow, they spread out and huge areas of reedbed form. In spring, great crested grebes pair up in a complex and beautiful courtship ceremony, and hobbies - small, agile birds of prey - swoop low to catch dragonflies in the summer sun.

Where our freshwater reaches the sea, vast mudflats can form. These habitats are a magnet to hundreds of thousands of overwintering wading birds, and they in turn attract peregrine falcons - the fastest animal on the planet*.

Whether it's our rare chalk streams, vast reedbeds, or rich mudflats, freshwater touches almost every corner of the British Isles, and every creature here relies on it.

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Key stories

Filming First

Atlantic salmon migration from sea to source - we believe this is the first time underwater drones have been used to film the journey in this way, swimming with the fish as they migrate. The team attached cameras to underwater remote-controlled drones in order to capture this footage, which took 71 days to film - the longest of any sequence on the Wild Isles series - including waiting for nine days to film the salmon leaping up waterfalls. The crew enlisted the help of a local expert in Scotland, a former fisherman, to help them understand the salmon behaviour and get up close with the drones.

New/Remarkable Behaviour

Bat lek - filmed in the North Yorkshire Moors, this is believed to be the first ever bat lek filmed using high-speed infra-red cameras, capturing a group of males of different species coming together at night and flying in circles in an attempt to impress females.

New/Remarkable Behaviour

Mayflies - over many years, the team captured the emergence of over one million adult mayflies. These flying insects have no mouths and their sole purpose as adults is to breed.

Rare Habitat

Chalk streams - our chalk streams are almost unique to England, with most found in southern England. There are only 200 known globally and 85 per cent of them are in England*. An amazingly rare habitat, which makes them more special. They are a haven for iconic species like the otter, kingfisher, and salmon.

Interview with producer Chris Howard

What role does freshwater play in supporting different kinds of wildlife?

Well apart from the obvious (it's water!) freshwater provides all kinds of different habitats and hiding places for so many different species of plant and animal. From the cold, fast flowing, highly oxygenated water of our uplands which are perfect for migratory fish such as salmon and seat trout, to the slower moving water bodies where grebes and mayfly dance and bats hunt. Not to mention our pools, lakes and lochs which host an incredible array of invertebrates from raft spiders to dragonflies, birds such as hunting hobbies and mammals like the beavers that are making a welcome comeback across Britain and Ireland.

Sadly, many of our rivers and lakes are now heavily polluted by human and agricultural waste*, and we over-extract to such an extent than many of our crucial chalk streams now run dry every summer. Freshwater is a vital resource - and one all too often taken for granted.

You interacted with lots of freshwater species in this episode, are there any that really stuck in your mind?

The two that really stick in my mind are the bats and the knot. The bats because until we switched the infra-red cameras on to film their incredible hunting and swarming behaviour - you really wouldn't have known they were even there. Once we could see using the cameras though, their unbelievable agility, speed and manoeuvrability became apparent - they were flying all around and between the crew the whole time and we just wouldn't have known it!

I spent one magical half hour lying on the ground watching the bats swarm silhouetted above me - a moment I will never forget as the click and calls were just about audible as they swooped low above me and they even came so close you could feel the wind from their wing beats on your face. As for the knot - the spectacle of a hundred thousand waders taking to the air to avoid a stooping peregrine just as the sun sets is hard to beat.

It also shows the importance of our estuaries - vital fuelling stations for migratory birds each winter - and is extra special because it only really happens three or four times a year when the tides, light and weather all come together. Spectacular.

What kit did you need to film the Atlantic salmon migrating over two years?

Where do I start! Because I was trying to film as much of the migration as possible this was a shoot that required all the toys...from high-speed cameras to film the leaping fish to remote cameras to try to catch otters. We built bespoke hides where we thought eagles might be coming down, flew drones over at least six different rivers and put out small underwater rigs to catch spawning behaviour. But the piece of kit that probably made this most exciting was our underwater drone, or ROV.

These Remotely Operated Vehicles are usually used for underwater surveying, checking manmade structures for defects and the like, so this was quite a novel use for it. Richard 'Taff' Davis is a fisherman who has all but hung up his rods in exchange for cameras, he had been experimenting with filming salmon underwater for years and knew better than anyone how skittish they can be with people and kit in the water. But his initial trials of the ROV were promising - for some reason the fish didn't seem to mind a bright yellow submarine where they would flee when almost anything else entered the water!

By manoeuvring the ROV slowly and with the greatest of care, Taff was able to get close to the fish like never before. This gave us some unique views; shoals of fish gathering off the coast before starting their migration; large groups waiting in the shallows for the rain to come; and the shot that Taff was most keen to get of all, an underwater shot of the salmon taking off on their epic leaps.

Can you tell us more about filming the bat lek. Why are they so elusive? How did you manage to capture this?

Filming the bat swarm has been on my radar for YEARS. Professor John Altringham is one of the leading bat experts in the British Isles and I had worked with him before, so when I started on Wild Isles, I called him up to discuss potential bat ideas. He had discovered the swarming site many years before and thought there was a good chance we might reveal what was happening in a detailed and visually attractive way.

We used a high-speed infra-red camera usually used for scientific research - this was one of its first forays into wildlife filming so using it was a bit of a punt. To make it work, we rigged up the swarm site with a lot of infra-red lights (we have to use infra-red as the bats are disturbed by white light), set the camera up and settled down to wait with bat detectors spread around at crucial points. By 11pm there were only a few bats circling, but slowly numbers started to build and suddenly around midnight the detectors erupted and once we turned the camera on, the arena was full of around 15-20 bats.

We set to work and cameraman Mark Payne-Gill was soon getting his eye in. Filming the bats in the pitch black when you can only see them through the camera, and when they dance around constantly, was an almost impossible task and to this day I have no idea how he managed to get most of the shots he did. The rest of us rushed around in the dark, tripping over ourselves as we furiously adjusted the lights rigged in the trees and on the steep slopes and changing batteries which the lights went through at an incredible rate.

Sadly, we only really had three nights with good numbers as the bats are very sensitive to wind, rain and temperature - so even though the shots we got show the swarm like it has never been seen before, it still feels like unfinished business and I would love to go back and try again.

Interview with Camerawoman Katie Mayhew

Why did you want to be involved in a series about wildlife in the British Isles?

Ever since I first heard of the series, I was eager to work on it. There is something incredible about being able to work in your home country and capture the wildlife you have grown up around. It's important to me to show others what we have in Britain and Ireland and hopefully change people's perspectives on a few species too. For example, adders aren't that scary or harmful but they are beautiful and elegant. Sadly though, like a lot of our species in the British Isles their numbers are in rapid decline and need help being protected and bringing back habitat for them.

What were your favourite species to film in this series?

This is a really tricky question for me as I enjoyed filming many species of plants and animals for this series. However, the top few would definitely be adders, toads, tawny owls and fungi.

Can you explain the underwater filming techniques you used when filming the toads?

We really wanted to film some split rig shots in the spawning pond so that you could see the toads mating in a wider pond setting. This involved Holly Tarplee, our underwater camerawoman, standing in waders in the pond for hours whilst moving the camera around the reeds and trying not to fall into the deeper waters. It's was a jolly cold job to do in March in the dark but it was all worth it and Holly did a fab job. These shots then cut really well with the close-up shots I filmed of toads underwater.

Filming locations and species filmed

Hobbies & dragonflies: Somerset; Wiltshire

Salmon: Scottish Highlands

Beavers: Scotland

Raft spiders: Dorset

Caves & Bats: North Yorkshire Moors; Northern Ireland

Mayfly: The River Avon

Toads & leeches: Somerset; Dartmoor

Great crested grebe: Cardiff; Suffolk

Knots and peregrine falcons: Norfolk; Dee Estuary

Credits

Series Producers

Alastair Fothergill

Hilary Jeffkins

Episode four Producer

Chris Howard

Notes to editors

*There are only 200 chalk streams known globally and 85 per cent of them are in England

[Source: Wildlife Trusts]

*Most of our rivers and lakes are now heavily polluted by human and agricultural waste

[Source: BBC News & the Environment Agency]

*Peregrine falcons are the fastest animal on the planet

[Source: Guinness World Records]

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