0:00:06 > 0:00:10Scoured by ice and weathered by storms...
0:00:14 > 0:00:21..20,000 square miles of rugged coastline, lochs and mountains.
0:00:24 > 0:00:27On the face of it, it looks bleak and lifeless...
0:00:27 > 0:00:31but wildlife is thriving in this unforgiving place...
0:00:32 > 0:00:34..if you know where to look.
0:00:37 > 0:00:38The seasons may be harsh...
0:00:41 > 0:00:43..and the opportunities fleeting.
0:00:45 > 0:00:49But animals and people have found ways to succeed here,
0:00:49 > 0:00:51turning adversity into advantage.
0:00:54 > 0:00:58This is Scotland's wild heart
0:00:58 > 0:01:00- the Highlands.
0:01:39 > 0:01:44It's late March in the Cairngorm mountains and the hills are on fire.
0:01:53 > 0:01:56The old heather is being put to the torch
0:01:56 > 0:01:59to stimulate new growth for the grouse season.
0:02:05 > 0:02:08Traditionally, this inferno marks the end of winter
0:02:08 > 0:02:10and the start of spring in this wilderness.
0:02:15 > 0:02:19But spring is the most unpredictable of all the seasons in the Highlands.
0:02:35 > 0:02:40Temperatures regularly range from -10 to 20 degrees.
0:02:40 > 0:02:44So, to achieve success here, animals have to battle with the extremes.
0:02:49 > 0:02:50It's all about timing.
0:02:58 > 0:03:04Mate, nest, or give birth at the wrong time and lives can be lost.
0:03:12 > 0:03:16But get it right and these mountains, forests
0:03:16 > 0:03:19and rivers provide the perfect place to raise the next generation.
0:03:19 > 0:03:21BIRD CHIRPS
0:03:29 > 0:03:34It can be so good that some travel thousands of miles to reap
0:03:34 > 0:03:36the bounty the Highlands has to offer.
0:04:35 > 0:04:36It's an osprey.
0:04:39 > 0:04:42Newly arrived from his wintering grounds in West Africa
0:04:42 > 0:04:45and heading back into the heart of the Highlands.
0:04:50 > 0:04:54200 pairs of ospreys make the Highlands vast network of river,
0:04:54 > 0:04:56loch and mountain their home.
0:05:02 > 0:05:06The hills start to rise just 20 miles north of the country's
0:05:06 > 0:05:09Central Belt and cover two thirds of the entire nation.
0:05:11 > 0:05:16To most of the world, the Highlands define what Scotland is all about.
0:05:20 > 0:05:21BIRD CAWS
0:05:25 > 0:05:27One mile south of iconic Loch Ness,
0:05:27 > 0:05:31this valley has been home to breeding ospreys for a decade.
0:05:37 > 0:05:39OSPREY CALLS
0:05:40 > 0:05:44The female is already on the nest, waiting for her mate.
0:05:49 > 0:05:53They've spent the winter in different parts of Africa
0:05:53 > 0:05:55but osprey's mate for life
0:05:55 > 0:05:59and now they're reunited on the same nest they used last year.
0:06:01 > 0:06:06But, after the gales of winter, it needs some urgent home improvements.
0:06:20 > 0:06:24Already more than five feet wide, this platform will need to
0:06:24 > 0:06:29withstand strong winds, heavy rain and maybe even sleet or snow.
0:06:52 > 0:06:55They need to complete the makeover as quickly as possible
0:06:55 > 0:06:58because, once the eggs are laid, the female won't leave the nest
0:06:58 > 0:07:00until she's raised her family.
0:07:04 > 0:07:09For the next 13 weeks, she'll be completely dependent on the male.
0:07:16 > 0:07:19Spring's the busiest time for the animals in the valley.
0:07:23 > 0:07:25Brown hares, curlews,
0:07:25 > 0:07:28and stoats are all getting ready for the breeding season.
0:07:36 > 0:07:40This male roe deer is keeping close watch on a female,
0:07:40 > 0:07:42but she won't let him near.
0:07:45 > 0:07:47She's already heavily pregnant
0:07:47 > 0:07:50and searching for a quiet spot to give birth.
0:08:00 > 0:08:04The next few days will be critical for all the wild animals here.
0:08:05 > 0:08:07A new generation is about to arrive.
0:08:09 > 0:08:12But the conditions are still far from settled.
0:08:23 > 0:08:26Although it's now April, the temperatures still haven't
0:08:26 > 0:08:29climbed above 10 degrees and clouds hang heavy
0:08:29 > 0:08:33from Loch Awe in the west to the Cairngorms in the east.
0:08:52 > 0:08:55But, in the great Caledonian pine forest of Abernethy,
0:08:55 > 0:08:57there's change in the air.
0:09:10 > 0:09:11It's a red squirrel.
0:09:15 > 0:09:18Although they've been displaced by grey squirrels in most
0:09:18 > 0:09:21of Britain, they're thriving here in the Caledonian Forest.
0:09:21 > 0:09:25There are 120,000 of them in Scotland -
0:09:25 > 0:09:2875% of the British population - and they're increasing.
0:09:34 > 0:09:37The habitat here is ideal for them, with abundant food
0:09:37 > 0:09:39and plenty of potential nest sites.
0:09:53 > 0:09:56With double jointed ankles and small, sharp claws,
0:09:56 > 0:09:58they can get up and down trees fast.
0:10:07 > 0:10:10Early spring is a busy time for red squirrels.
0:10:15 > 0:10:18Already pregnant with kittens, this female is
0:10:18 > 0:10:22looking for a comfortable nest site, away from predators.
0:10:27 > 0:10:30She'll either build a drey from twigs and leaves
0:10:30 > 0:10:32or use an uninhabited tree hole.
0:10:43 > 0:10:45She'll need to keep searching.
0:10:45 > 0:10:48But this female's territory is large,
0:10:48 > 0:10:51she's got 17 acres of pine forest and river to search yet.
0:10:56 > 0:10:5850 miles beyond the forest, on the River Braan,
0:10:58 > 0:11:02a pair of special Highland birds have already built their nest.
0:11:09 > 0:11:13They're dippers, birds that are marvellously
0:11:13 > 0:11:16adapted for life in this fast-changing environment.
0:11:19 > 0:11:23Britain's only aquatic songbird, dippers have waterproof plumage
0:11:23 > 0:11:27to keep them dry, and long, flexible feet for gripping slippery rocks.
0:11:34 > 0:11:38Their white bibs and dark bodies keep them well camouflaged as
0:11:38 > 0:11:42they dive for insect larvae amongst the boulders and rapids.
0:11:43 > 0:11:46In spring, these are in plentiful supply.
0:11:50 > 0:11:51DIPPER CHIRPS
0:12:12 > 0:12:15The dippers are working nonstop as they've already got
0:12:15 > 0:12:17hungry mouths to feed.
0:12:21 > 0:12:23Carefully covered by a neat moss dome,
0:12:23 > 0:12:26the nest's position may look dangerous...
0:12:29 > 0:12:32..but it offers total protection from predators
0:12:32 > 0:12:33like stoats and weasels.
0:12:46 > 0:12:49Food goes in and waste comes out.
0:13:15 > 0:13:18Even a large fish is delivered,
0:13:18 > 0:13:20an indication that the chicks are well-grown.
0:13:28 > 0:13:32For now, the river's level is just right for the chicks to make
0:13:32 > 0:13:33an easy exit.
0:13:35 > 0:13:39But if heavy rain arrives, the waterfall will become a torrent,
0:13:39 > 0:13:41which could sweep the nest away.
0:13:51 > 0:13:54At last, the weather is warming.
0:13:54 > 0:13:58For the first time this year, temperatures climb to 15 degrees.
0:13:59 > 0:14:04It's now a priority for the Highland animals to feed themselves up,
0:14:04 > 0:14:06ready for the next phase of spring.
0:14:39 > 0:14:42Over the next couple of months, the male osprey will need to
0:14:42 > 0:14:45catch more than 400 fish to keep his family going.
0:15:04 > 0:15:09He makes hunting look easy but it's a game of stealth and patience.
0:15:12 > 0:15:15Only one in four strikes are successful.
0:15:28 > 0:15:32He needs to find a fish in the right position and get the speed,
0:15:32 > 0:15:35angle and point of entry exactly right.
0:15:54 > 0:15:57After hitting the water and grabbing the fish,
0:15:57 > 0:16:01the game still isn't over for the osprey in its quarry.
0:16:05 > 0:16:07He needs to get airborne again.
0:16:20 > 0:16:23His talons are equipped with adhesive scales
0:16:23 > 0:16:26and long, curved claws for an unbreakable hold.
0:16:27 > 0:16:30But a big trout can match him weight-for-weight
0:16:30 > 0:16:33and the instinct of the fish is to swim down.
0:16:38 > 0:16:42There are tales of weak and hungry ospreys being dragged to the bottom,
0:16:42 > 0:16:46unable to release the fish or lift off from the water successfully.
0:17:02 > 0:17:06But osprey wings are adapted to give maximum lift from the water.
0:17:11 > 0:17:14And this male is young and strong.
0:17:19 > 0:17:21This is a struggle he's destined to win.
0:17:52 > 0:17:55He carries the fish headfirst,
0:17:55 > 0:17:58making it easier to fly the 20 mile journey home.
0:18:10 > 0:18:13Back in the valley, the female waits in the nest.
0:18:18 > 0:18:21Their need to feed is even more urgent now.
0:18:28 > 0:18:30She's no longer alone in the nest.
0:18:33 > 0:18:36There are definitely chicks in there!
0:18:45 > 0:18:47They're not the valley's only new arrivals.
0:18:50 > 0:18:55Deep in the long grass, at the edge of the field, lies another new baby.
0:18:58 > 0:19:02With immaculate camouflage, it instinctively lies motionless.
0:19:08 > 0:19:10The roe deer has given birth.
0:19:23 > 0:19:25Leaving her offspring alone like this
0:19:25 > 0:19:27seems like a high-risk strategy.
0:19:29 > 0:19:30But the mother needs to feed
0:19:30 > 0:19:34and the youngster is too young to run away from danger,
0:19:34 > 0:19:36so hiding is the only option.
0:20:01 > 0:20:04The mother approaches warily.
0:20:04 > 0:20:07She mustn't reveal the location to any watching predators,
0:20:07 > 0:20:09like eagles or foxes.
0:20:22 > 0:20:26But it's not predators that are the greatest threat to young roe deer.
0:20:28 > 0:20:31A sudden drop in spring temperatures could be fatal.
0:20:57 > 0:20:59The male osprey is back with the fish.
0:21:03 > 0:21:06He's now got a lot more mouths to feed.
0:21:08 > 0:21:10There are three hungry chicks in the nest.
0:21:18 > 0:21:22Fuelled by their high protein fish diet, osprey chicks become
0:21:22 > 0:21:24full size in just five weeks.
0:21:29 > 0:21:33And once they're 12 weeks old, they face an even bigger test.
0:21:35 > 0:21:36A flight to distant Africa.
0:21:54 > 0:21:59Just one mile north of the ospreys' valley lies the Great Glen.
0:22:04 > 0:22:07Once a mighty glacier, it divides the Highlands in two.
0:22:09 > 0:22:13At its heart is the most famous body of water in Scotland...
0:22:18 > 0:22:19..Loch Ness.
0:22:28 > 0:22:31It deserves its legendary reputation.
0:22:31 > 0:22:3523 miles long, it contains more fresh water
0:22:35 > 0:22:38than all the lakes in England and Wales combined.
0:23:07 > 0:23:11As for the monster...it still hasn't been found.
0:23:14 > 0:23:17But the Highlands are full of mysterious creatures.
0:23:23 > 0:23:25POPPING NOISE
0:23:28 > 0:23:33It's 4am in Abernethy Forest, and something is stirring.
0:23:53 > 0:23:57Capercaillie - the world's biggest grouse.
0:24:05 > 0:24:08There are just over 1,000 left in Scotland...
0:24:09 > 0:24:12..and their stronghold is here in the pine forest.
0:24:26 > 0:24:30Their bizarre popping call penetrates deep into the forest.
0:24:34 > 0:24:37It attracts the females to a ritualistic display
0:24:37 > 0:24:39called a lek.
0:24:43 > 0:24:45Here, in a forest clearing,
0:24:45 > 0:24:48the males will compete for the right to mate exclusively
0:24:48 > 0:24:50with all the females.
0:24:57 > 0:25:00Weighing in at more than 4kg,
0:25:00 > 0:25:02this young male is in superb condition.
0:25:13 > 0:25:15But an older male is up for the fight, too.
0:25:22 > 0:25:26This veteran, with a bald patch on his neck, has been
0:25:26 > 0:25:28king of the lek for many years.
0:25:42 > 0:25:46The females look on from the treetops desperate to see
0:25:46 > 0:25:48which suitor will be victorious.
0:25:55 > 0:25:56It's time to raise the stakes.
0:26:08 > 0:26:09Game on!
0:26:24 > 0:26:28They're evenly matched - it's simply a question of who gives way first.
0:26:39 > 0:26:41The younger male is on the run...
0:26:41 > 0:26:44handing victory to the dominant, older bird.
0:26:54 > 0:26:59Like an Emperor of the forest, he's retained mastery of the lek.
0:27:00 > 0:27:02All the females are his.
0:27:11 > 0:27:15Nearby, the female squirrel is feeding on pine cones.
0:27:22 > 0:27:26The small seeds between the scales are a protein-rich food source
0:27:26 > 0:27:30and she needs extra nourishment now.
0:27:30 > 0:27:32She's just given birth.
0:27:35 > 0:27:38There are two new kittens,
0:27:38 > 0:27:41hidden deep in her drey high up in a Scots pine.
0:27:47 > 0:27:49Soft moss is ideal for lining the nest.
0:28:00 > 0:28:03Squirrels are fastidiously clean animals.
0:28:06 > 0:28:10But the tiny and blind babies can't leave the nest for a toilet break.
0:28:12 > 0:28:15So, regularly changing the bedding is an important part
0:28:15 > 0:28:17of the female squirrel's routine.
0:28:19 > 0:28:22Although the drey is only ten inches across,
0:28:22 > 0:28:27it takes at least six mouthfuls of moss to fill it up and make it snug.
0:28:33 > 0:28:36Once the youngsters are able to grip and climb,
0:28:36 > 0:28:38they'll start leaving the drey to explore.
0:28:43 > 0:28:45But that's still many weeks away.
0:28:46 > 0:28:51So, for now...she's stuck with this time-consuming chore.
0:29:15 > 0:29:19High above Abernethy Forest, snow is still lying thick
0:29:19 > 0:29:23and deep on Cairngorm, Cairn Toul and Ben Macdui.
0:29:28 > 0:29:32But it's 1st May, and spring is picking up pace.
0:29:36 > 0:29:41Further down on the moorland edge, wild flowers are coming into bloom.
0:29:42 > 0:29:46Bumblebees are buzzing... and newborn lambs are playing.
0:30:13 > 0:30:16There we go, shall we empty your bucket, Ernestine?
0:30:17 > 0:30:21But despite the sunshine, the hill farmers know that it's still
0:30:21 > 0:30:24too early to risk taking the sheep on to the mountains.
0:30:25 > 0:30:28Even in May, heavy snow can fall in the Highlands,
0:30:28 > 0:30:33so, for now, they'll feed them here in the valley, close to the farm.
0:30:33 > 0:30:36SHEEP BAA
0:30:48 > 0:30:51But for the wild creatures of the Highlands,
0:30:51 > 0:30:55there's no chance of holding back and waiting for better conditions.
0:30:55 > 0:30:58They just have to make the best of it, whatever the weather.
0:31:07 > 0:31:09Tawny owl and wagtail chicks
0:31:09 > 0:31:12are already on the verge of independence.
0:31:16 > 0:31:19And the osprey chicks are growing fast, too,
0:31:19 > 0:31:21demanding more and more fish from the male.
0:31:32 > 0:31:34The roe deer can sense change is coming.
0:31:38 > 0:31:40Her youngster is now more mobile
0:31:40 > 0:31:44and she's instinctively moving it towards higher ground.
0:31:45 > 0:31:47It could be a wise move.
0:31:47 > 0:31:50This valley has flooded many times in the past.
0:32:02 > 0:32:04She can't help it across the fence.
0:32:05 > 0:32:09Now it's a week old, it has to work the problem out for itself.
0:32:09 > 0:32:10FAWN CRIES OUT
0:32:13 > 0:32:17THUNDER RUMBLES
0:32:17 > 0:32:19The weather has taken a turn for the worst.
0:32:22 > 0:32:23It's deteriorating fast.
0:32:30 > 0:32:33Temperatures are sliding into single figures
0:32:33 > 0:32:37and a cold front is now sweeping in from the Atlantic.
0:32:40 > 0:32:42Heavy rain is on its way.
0:33:34 > 0:33:36THUNDER RUMBLES
0:33:45 > 0:33:48The three osprey chicks huddle beneath their mother's wings.
0:33:50 > 0:33:52The nest is vulnerable now.
0:33:53 > 0:33:57Spring downpours like this have been known to destroy osprey nests.
0:34:15 > 0:34:18But for the dipper family, the situation is far more serious.
0:34:26 > 0:34:30Practically a month's rain has fallen in 24 hours
0:34:30 > 0:34:31and the river is still rising.
0:35:12 > 0:35:16The torrent has completely obscured the little nest and the adults
0:35:16 > 0:35:20can only get in and out by flying behind the wall of water.
0:35:27 > 0:35:30It's the worst possible time for the chicks to fledge.
0:35:34 > 0:35:36But the adults are calling them out.
0:35:40 > 0:35:41There's no option now.
0:35:43 > 0:35:46If they stay inside any longer, they'll be drowned.
0:35:58 > 0:35:59They're in mortal danger.
0:36:03 > 0:36:08Young dippers are weak flyers. One mistake and it's all over.
0:36:34 > 0:36:35One across.
0:36:45 > 0:36:47The other four seem reluctant to go.
0:36:52 > 0:36:55The female has stopped feeding the chicks to encourage them out.
0:36:58 > 0:37:00If they're to eat, they must leave.
0:37:11 > 0:37:13They're using the same route as the first chick.
0:37:19 > 0:37:22But the surface is wet and slippery.
0:37:27 > 0:37:29There's just one left in the nest.
0:37:34 > 0:37:38It's made it across. They're all out on their own.
0:37:45 > 0:37:47The chicks are desperate for food.
0:37:56 > 0:38:00But rather than help her young, the females goes straight back to
0:38:00 > 0:38:02repair the nest for a second brood.
0:38:03 > 0:38:06The desire to reproduce is more powerful than feeding
0:38:06 > 0:38:07the newly-fledged young.
0:38:13 > 0:38:14Without guidance from the adults,
0:38:14 > 0:38:17the chicks could still be washed away.
0:38:20 > 0:38:22This one's far too close to the edge.
0:38:27 > 0:38:30But the male is calling him upriver, away from danger.
0:38:34 > 0:38:38Little...by little.
0:38:51 > 0:38:53And, at last, he gets his feed.
0:38:59 > 0:39:01Now for the first dip.
0:39:14 > 0:39:19Dipper chicks need to swim well from soon after they emerge.
0:39:19 > 0:39:22In a week, their father's attention will end
0:39:22 > 0:39:24and they'll have to catch their own food.
0:39:34 > 0:39:38Despite the perilous location, dippers have nested here
0:39:38 > 0:39:40on this Highland river for many years.
0:39:43 > 0:39:46And, hopefully, will be here for generations yet.
0:40:22 > 0:40:28At last, after two days of constant rain, the weather has cleared.
0:40:32 > 0:40:34The osprey nest is intact...
0:40:38 > 0:40:40..the young roe deer is thriving...
0:40:43 > 0:40:47..and the squirrel kittens make their first forays from the drey.
0:40:52 > 0:40:54Now temperatures are rising.
0:41:00 > 0:41:03And the Caledonian pine forest is awakening.
0:41:09 > 0:41:11Warmed by the rays of the sun,
0:41:11 > 0:41:14the understory now seethes with life.
0:41:20 > 0:41:22They're Scottish wood ants.
0:41:41 > 0:41:45Over six feet wide and teeming with a colony 100,000 strong,
0:41:45 > 0:41:49this nest has stood in the heart of the forest for decades.
0:42:01 > 0:42:04With the sun now high overhead, the ants will do everything
0:42:04 > 0:42:07they can to get the benefits of the warmth it brings.
0:42:12 > 0:42:16Teams of female worker ants sunbathe on the surface in shifts.
0:42:23 > 0:42:27Once they've heated up, they travel deep into the nest,
0:42:27 > 0:42:31to transfer their warmth to the eggs and larvae in the brood chambers.
0:42:37 > 0:42:41On the forest floor, ants swarm along regular trails
0:42:41 > 0:42:44capturing insects to bring back to the nest for food.
0:42:47 > 0:42:51Because these insects eat plants, this, in turn, protects trees
0:42:51 > 0:42:53and saplings from destruction.
0:42:57 > 0:43:01So, remarkably, these tiny ants safeguard the future of the forest.
0:43:27 > 0:43:30Rare timberman beetles also emerge in spring.
0:43:34 > 0:43:37With antennae four times the length of his body, this is
0:43:37 > 0:43:42the longest insect in Britain and another real pine forest speciality.
0:43:47 > 0:43:48He's just emerged as an adult,
0:43:48 > 0:43:51after spending two years as a bark-eating grub.
0:43:55 > 0:43:57And he's on a mission to mate.
0:44:12 > 0:44:17Quite why the antennae are so long is something of a mystery
0:44:17 > 0:44:21but it's certain that picking up the smell, sound and taste
0:44:21 > 0:44:24of a female beetle is a major reason for their incredible length.
0:44:33 > 0:44:35He's got a female in his sights.
0:45:00 > 0:45:02A successful meeting.
0:45:13 > 0:45:17The female will now lay her eggs in a suitable cleft in the bark,
0:45:17 > 0:45:20but it will be the last act of her life.
0:45:22 > 0:45:25The adult beetles live for just a couple of months.
0:45:58 > 0:46:01Back in the valley, the osprey chicks are exercising
0:46:01 > 0:46:03their young wings in the sun.
0:46:09 > 0:46:10They're almost ready to fly.
0:46:15 > 0:46:18And they're not the only ones enjoying the warmth.
0:46:21 > 0:46:25Common lizards live in the dry-stone wall beneath the nest.
0:46:25 > 0:46:28The Highlands are on the very northerly edge of their range
0:46:28 > 0:46:31as they can't live without sunshine.
0:46:31 > 0:46:33So now is the time they're most active.
0:46:43 > 0:46:47They're safe from the fish-eating ospreys but they do have enemies.
0:47:01 > 0:47:04Adders - Scotland's only poisonous snakes.
0:47:11 > 0:47:14The lizards need to constantly watch for danger.
0:47:24 > 0:47:27But, today, the snakes are unlikely to strike.
0:47:28 > 0:47:30They're about to shed their skins.
0:47:41 > 0:47:44Yawning wide may help stretch the skin to help it split.
0:47:49 > 0:47:51But the moult will take many days..
0:47:53 > 0:47:55..and the lizards are safe...
0:48:00 > 0:48:01..for now.
0:48:03 > 0:48:05OSPREY CALLS
0:48:09 > 0:48:12The female osprey's calling in alarm...
0:48:14 > 0:48:17..and down go the chicks into the bowl of the nest.
0:48:21 > 0:48:23There's an intruder in the valley.
0:48:29 > 0:48:32It's another osprey, a male who's failed to find his own
0:48:32 > 0:48:34territory this year and he wants to move in.
0:48:43 > 0:48:46He wouldn't try to kill the chicks but if they were
0:48:46 > 0:48:49knocked from the nest they'd be unable to fly back to safety.
0:48:57 > 0:48:59That's far too close.
0:48:59 > 0:49:01Time for direct action from the male.
0:49:17 > 0:49:18And up flies the female.
0:49:32 > 0:49:35Female ospreys are much bigger than males
0:49:35 > 0:49:38and quite capable of seeing off an unwanted intruder.
0:49:43 > 0:49:45Especially when there are chicks in the nest.
0:49:52 > 0:49:53The family is safe.
0:50:01 > 0:50:04It's now only a matter of days before the youngsters
0:50:04 > 0:50:05make their first flight.
0:50:19 > 0:50:22The wheel of the seasons is turning...
0:50:23 > 0:50:26..and spring is rapidly becoming summer.
0:50:38 > 0:50:42The mountains and glens are at their greenest as the natural world
0:50:42 > 0:50:44enters its busiest time in the Highlands.
0:50:55 > 0:50:58And nowhere is this more evident than in the sea.
0:51:05 > 0:51:09Here in the Moray Firth, a pod of dolphins are heading to a feast.
0:51:18 > 0:51:22They're bottlenose dolphins, one of 23 different species
0:51:22 > 0:51:25of cetacean that have been seen off Scottish coasts.
0:51:30 > 0:51:34Nearly 200 individuals have been recorded here socialising,
0:51:34 > 0:51:36breeding and hunting together.
0:51:45 > 0:51:48They usually seek out mackerel, squid and herring
0:51:48 > 0:51:51but there is one species of fish that the bottlenose dolphins
0:51:51 > 0:51:52prize above all others...
0:51:57 > 0:51:58..Atlantic salmon.
0:52:08 > 0:52:12With Highland rivers now swollen to the brink, due to heavy rain,
0:52:12 > 0:52:16the fish are heading towards the interior to start their journeys
0:52:16 > 0:52:17to the spawning grounds.
0:52:23 > 0:52:26And the dolphins will be waiting for them.
0:52:29 > 0:52:33The best place to ambush the fish is Chanonry Point near Inverness.
0:52:58 > 0:53:01The tidal run here means the fish are directed
0:53:01 > 0:53:03into a deep and narrow channel
0:53:03 > 0:53:04where the dolphins wait
0:53:04 > 0:53:07to ambush them in the murky, fast-moving water.
0:53:14 > 0:53:18Very big fish are running today. Some are 20lbs or more.
0:53:28 > 0:53:31But swallowing such a huge fish isn't easy.
0:53:44 > 0:53:48They need to slip down in exactly the right way and that means
0:53:48 > 0:53:52regurgitating and reswallowing until the position is exactly right.
0:54:00 > 0:54:03Sometimes twisting your body actually seems to help.
0:54:19 > 0:54:21And down it goes.
0:54:26 > 0:54:29Over the next few weeks, the dolphins will be catching more
0:54:29 > 0:54:32and more salmon as the fish start their migratory
0:54:32 > 0:54:34journey into the heart of the Highlands.
0:54:43 > 0:54:47But other migrants will be leaving the Highlands behind.
0:55:00 > 0:55:02In the valley, there are big changes.
0:55:31 > 0:55:34All three chicks have learned to fly and are spending longer
0:55:34 > 0:55:36and longer out of the nest.
0:55:46 > 0:55:48Now the chicks can fly independently,
0:55:48 > 0:55:50their parents are preparing to switch roles.
0:55:52 > 0:55:55For nine weeks, the male has caught every single fish
0:55:55 > 0:55:57while mum has delivered all the care in the nest.
0:55:59 > 0:56:02Now the entire burden of childcare will shift to him.
0:56:11 > 0:56:14For the next fortnight, it'll be his job to teach them
0:56:14 > 0:56:16all he knows about how to soar,
0:56:16 > 0:56:20dive and catch fish before they head off on their epic migration.
0:56:28 > 0:56:32As for the female, relieved of her parental duties, she's already on
0:56:32 > 0:56:37her way south, starting out on the 3,000 mile journey to West Africa.
0:56:49 > 0:56:52The extreme spring weather of the Scottish Highlands provides
0:56:52 > 0:56:55endless challenges for all its residents.
0:57:00 > 0:57:03But animals here are resilient, adaptable and strong.
0:57:10 > 0:57:11For them, these mountains,
0:57:11 > 0:57:15forests and rivers offer unmatched opportunity.
0:57:32 > 0:57:36That's why the ospreys will return here year after year.
0:57:42 > 0:57:46Back to their home, in Scotland's living wild heart.
0:58:03 > 0:58:04Next time...
0:58:04 > 0:58:08Highland animals race towards independence before summer's end.
0:58:10 > 0:58:13Young otters need to stop playing and learn to catch fish.
0:58:15 > 0:58:18Golden eagles ceaselessly hunt for mountain hares.
0:58:20 > 0:58:24And tiny guillemot chicks face a desperate leap for life
0:58:24 > 0:58:27as they fall to the sea from 400-foot cliffs.