It's a universal dream to fly like a bird.

 To soar on wings into the heavens.

 But it's nothing compared to the reality.

 This is our planet seen as never before.

 A bird's-eye view.

 Theirs is a journey that covers the world.

 Filled with astonishing natural events extreme challenges and hard-won rewards.

 This is the world on the wing.

 Our story begins on the southern tip of Africa.

 A bird's-eye view of Cape Town's Table Mountain gives no hint of what's stirring in the seas far offshore.

 Beneath the waves a great gathering is occurring.

 Its innermost secrets are known by a bird.

 The Cape gannet. (塘鹅，any large, web-footed, seabird of the family Sulidae, having a sharply pointed bill, long wings, and a wedge-shaped tail, noted for its plunging dives for fish)

 An intelligent and curious creature that works as part of a team.

 Small groups spread out across the ocean looking for clues that might lead them to the great event.

 They keep their eye on humpback whales as they seek the same reward.

 But dolphins make even better allies.

 The two creatures work together.

 The gannets are the dolphins' eyes in the sky.

 From their high vantage point, the gannets can see what the dolphins can't. (a position or place that affords a wide or advantageous perspective; viewpoint)

One finally spots what they're looking for.

He dives, a signal to all his followers that they've finally arrived.

 20 meters dive, they reach their target.

 The Great Sardine Run, the biggest fish migration in the world. (洄游（的鱼群）)

 But at this depth the sardines are quite a challenge.

 He comes up with nothing.

 But guiding the dolphins here is about to pay off.

 They attack from below, breaking up the shoals and driving them to the surface.

 Now the sardines are much easier to catch.

 But the commotion also attracts bronze whaler sharks.

 At every dive, the birds now dice with death.

 And some hunters could swallow a dozen gannets in just one gulp.

 Fortunately, Bryde's whales are only here for the sardines.

 It's their extraordinary knowledge of ocean life that allows 65,000 pairs to thrive here.

 Back on the mainland, vultures have an unrivalled knowledge of the creatures that live on the land.

 These canny scavengers soar for hours, studying the movements of animals.

 Their all-seeing eyes watch for clues that might lead them to a meal.

 Running animals are a good sign.

 But lions are even better.

 But in the high-stakes world of the African bush, the watched also do the watching.

 There is an uneasy alliance between vultures and lions as both spy on one another to find fresh meat.

 This time there's nothing, but she will keep looking.

 Her bird's-eye view reveals many secrets.

 This S-shaped island is actually alive.

 It is made up entirely of lesser flamingos.

 Flamingos may be the most beautiful and graceful birds in Africa, but they spend their lives in the most unsavoury places.

 They wade in toxic soda lakes.

 The only lagoons where the algae they eat is found.

 They filter it from the caustic water with their bills.

 It not only keeps them alive, pigments in the algae create their flamboyant colour.

 As the amount of algae varies with the seasons, the flamingos are on a continual quest for the perfect lake.

 But wherever they go, these delicate birds fall prey to hunters of every kind.

 Fish eagles are their main enemy.

 These clever and solitary predators are found over every body of water south of the Sahara.

 They eat mainly fish, but here flamingos are easier prey.

 Fish eagles have become expert at hunting them.

 The fish eagle is small and highly manoeuvrable.

 But it still won't be easy.

 This battle plays out wherever flamingos roam.

 For now, the lake's algal bloom gives them all they could wish for.

 But all good things must end.

 Soon they will be gone.

 Vultures never get the chance to stop travelling.

 Her broad wings ride the air for hours as she searches for the dead or done for.

 Every feather reacts to the tiniest breath of air, adjusting its angle to perfect her flight.

 She splays her wing-tip feathers to reduce drag.

 And uses her tail to steer.

 Her efficient flight is helped by a weather phenomenon often found in these hot climes.

 Dust devils form when the sun bakes the ground and hot air rises in a thermal, sucking up dirt. (a small whirlwind 10–100 feet (3–30 meters) in diameter and from several hundred to 1000 feet (305 meters) high, common in dry regions on hot, calm afternoons and made visible by the dust, debris, and sand it picks up from the ground)(thermal: a rising air current caused by heating from the underlying surface, especially such a current when not producing a cloud)

 Thermals are usually invisible, but vultures know just where to find them.

 She uses them as express elevators to the sky.

 Just as she watches other vultures, they watch her too.

 Sharing their knowledge of where thermals can be found.

 When she finds lift, others rush to join her on her free ride.

 Gliding from thermal to thermal, she surveys hundreds of square kilometers with hardly any effort at all.

 A descending spiral of other birds marks the spot where a carcass might be found.

 She folds her wings to lose height and uses her legs as air brakes.

 Feathers along her wings spring up to slow her even more.

 With two and a half metres of wing to deal with, landing among trees is a challenge.

 Once down, the hard bit is finding the carcass.

 But backup is never far behind.

 The spiralling vultures have also attracted the lions.

 Things could easily turn nasty.

 Especially as something doesn't seem right.

 Swallows and carmine bee-eaters are here, not the usual suspects at a murder scene. (a crimson or purplish-red color)

Marabou storks, the undertaker birds, are more like it. (秃鹳) (funeral director)

 But these wily scavengers are not here for a carcass. (full of, marked by, or proceeding from wiles; crafty; cunning)

 They're eating termites.

 The vultures and lions have messed up, big-time. (a blunder; state of confusion; mix-up) (Very much; totally)

 It was an easy mistake to make.

 A gathering of birds always means food.

They weren't to know that for them it wouldn't even be a snack.

Only the smaller hooded vulture has the right tool for the job.(冠鹫)

 Much to the lion's frustration.

 When messing with lions, the stakes are high.

 Unfortunately, it's an occupational hazard.

 

Cape Point, at the southern tip of Africa, is home to another bird that mixes with dangerous predators.

Kelp gulls may not have the charisma of a vulture, but they certainly know their wildlife.

The aptly-named Seal Island is home to 10,000 Cape fur seals. The perfect meal, if only the gulls were hunters.

But by studying the seal's behaviour, these inoffensive birds have put seal meat at the top of their menu.

They pick out the youngest and wait for them to brave the open waters of the bay.

 Then they look for someone to prepare their meal.

 A great white shark will do nicely! To be first at the kill means a feast.

 But the shark has to catch dinner first.

 The commotion is a signal to other gulls.

 In the killing season, over 30 attacks happen around Seal Island each day.

 The gulls have become experts on the great white's killing technique.

 Back on the South African mainland, a very different wildlife spectacle occurs every evening.

 These are barn swallows. （家燕）

 Three million of them.

 They roost in these reed beds before travelling 9,500 kilometers to their spring breeding grounds in northern Europe. (a perch upon which birds or fowls rest at night. 2. a large cage, house, or place for fowls or birds to roost in. 3. a place for sitting, resting, or lodging. verb (used without object), to sit or rest on a roost, perch, etc. to settle or stay, especially for the night)

 They are well equipped for their migration.

 Few can beat their aerobatic skills.

 They even drink without missing a beat.

 Their streamlined body and long, pointed wings allow them to effortlessly manoeuvre, and their forked tail helps their sublime control.

 Taking a bath couldn't be easier.

 Their flying abilities will soon be tested as they embark on one of the riskiest and most epic journeys on earth.

 But they will not be alone.

 In the skies above, thousands of white storks join them in a race against time to reach their European breeding grounds.

 But while swallows flap their wings all the way, white storks glide on thermals.

 On a good day, the storks can travel 500 kilometers with hardly any effort at all.

 But flying isn't always such a breeze. (an easy task; something done or carried on without difficulty)

 They can only travel when the sun shines.

 Victoria Falls is a major landmark on their journey, 15,000 kilometers from where they first set off.

 As the Zambezi river plummets into the chasm below, it creates huge updraughts that make the falls a paradise for soaring birds.

 It's the perfect place for a fish eagle to set up home.

 It might be wet and wild, but these are the conditions eagles relish.

 He patrols the mile-long canyon, surfing on air pushed up by the falling water.

 Birds understand and feel the air currents in ways that are difficult to imagine.

 As well as detecting thermals, they see their landscape in terms of how it shapes and deflects the air.

 This knowledge allows them to glide with little effort, allowing them to concentrate on what really matters.

 Finding a meal.

 Swooping from the air provides the best element of surprise.

 the thermals that support storks in the air simply vanish.

 Below lies the problem.

 Lake Malawi.

 The first of many lakes in East Africa's Great Rift Valley.

 Thermals can't form over water, so the storks have to work hard just to stay airborne.

 And these soaring birds aren't designed to flap their wings for long.

 But a promising apparition suddenly appears.

 Dust devils seem to be rising from the lake.

 But these aren't thermals.

 In fact, they're made entirely of flies.

 Each month, billions of lake flies swirl together in a huge mating dance, creating the biggest swarms on Earth.

 Storks must head inland to find the real McCoy.

 But flapping flight takes its toll.

 Tired storks must make frequent stops to rest and feed.

 Tornadoes of flies may be useless for storks, but they are a godsend for the swallows travelling close behind.

 Like the storks, they have already flown over 1,000 kilometers at this point.

 They too are ravenous.

 They head into the very heart of the swarm.

 Swallows put on little weight before their journey, so must feed at every opportunity.

 Windfalls like this make the difference between life and death.

 Refuelled, they continue their travels.

 Further north, along the Rift Valley, the land opens up into a huge expanse of grassland.

 Here, vultures command the skies, soaring up to five kilometers above the Earth.

 From these heights, they can drop down at any time to check out a meal.

 Her favourite scavenging grounds are the Serengeti plains.

 Home to the largest land migration in the world.

 Below, around one and a half million wildebeest perform their yearly journey.

 Vultures escort the herd, and are an expert on their habits, especially as they might bring a meal.

 They know the torrential waters of the Mara river are an accident waiting to happen.

 Thousands of wildebeest must negotiate its dangerous waters and casualties are inevitable.

 The crocs have waited a year for this moment.

 They won't waste their chance.

 It's carnage.

 But there won't be much left for the vultures.

 But as the wildebeest reach the other side, a four-metre wall blocks their path.

 It's a death trap.

 All it takes is just one slip.

 And there it is.

 The perfect meal, ripe for the taking.

 Now the arguing begins.

 The marabou stork is back.

 He uses his bill to dismember carcasses.

 But he's quite happy to use it as a spear.

 Vultures never get to eat in peace.

 That's why they always keep moving.

 Flamingos are also driven by the quest for food.

 In desperate times, many travel up from southern Africa to join East African flamingos as they seek the perfect soda lake.

 Just south of the equator is Lake Nakuru, the most famous flamingo lake in the world.

 The lake is a favourite stopover for flamingos and thousands can arrive in a single day.

 But despite its past glory, it's now a bitter disappointment.

 A change in water quality means little algae grows here now.

 There are other signs of change.

 Great white pelicans arrive, attracted to the salt-tolerant fish that have been introduced by local fishermen to the lake.

 They cruise over the water surface, riding a cushion of air created by the down thrust of their wings.

 The recent appearance of pelicans shows that the lake is changing.

 The flamingos face other problems, too.

 Here, scavengers have turned hunters.

 The delicate flamingos make easy prey for the hyenas.

 They need space for takeoff.

 It's not good to be at the back of the queue.

 And to make things worse, many have been weakened by a lack of food.

 The hyenas' technique is crude but effective.

 Just charge and grab the slowest.

 Lake Nakuru has become a dangerous place with few attractions.

 Hungry and out of condition, the flamingos must try their luck elsewhere.

 Above, the storks continue their migration.

 They carry few reserves and need to make frequent stops to feed.

 Here, the open plains are their best chance of catching the insect life they need.

 But stopovers bring their own hazards.

 The hungry lion will hunt anything.

 Fortunately for the storks, the lions have set their sights on bigger prey.

 On his 6,000-mile safari, the stork must be ready for anything.

 Some birds can't get enough of hunting lions.

 One vulture has hit the jackpot.

 The lionesses have killed.

 And so too has the male.

 She makes her choice.

 Finding the carcass is easy.

 Getting it from the owner won't be.

 Some sneaky tactics are required.

 Tiptoeing around the back could be the answer.

 Hungry lions may be big, but they aren't stupid.

 Dealing with the vulture would be like swatting a gnat.

 Hardly worth the effort.

 But reinforcements arrive, swelling the ranks.

 They include the more burly lappet-faced vultures.

 She has attracted strong support but she must be careful.

 Her masterplan is simple, but dangerous.

 Tease the lion to distraction.

 Lions get hot and bothered keeping vultures from their kill.

 And that's exactly what they want.

 The vulture plays dare, goading the lion.

 In the hot sun, it is a war of attrition.

 Their cunning plan has worked.

 The lion heads for shade.

 Vultures rush in where others fear to tread.

 Now it's everyone for themselves.

 Then the neighbours from hell arrive.

 Somewhere in the mayhem, everyone eventually gets something.

 High in the skies above, the flamingos continue their quest for the perfect lake.

 Just past the equator, in central Kenya, they finally find it.

 Lake Bogoria.

 Here, flamingos gather in their millions, the greatest concentration on Earth.

 Breathtaking gatherings like these happen just once in 20 years.

 Their bodies become a pink blanket, veiling the shallows of the lake.

 For the new arrivals, the lake lives up to its promise.

 It's brimming with all the algae they can eat.

 At Lake Bogoria, they can stop for a while and feed to their heart's content.

 They have reached their Shangri-la.

 But there's trouble in paradise.

 Here, baboons have turned killers.

 And it's not only baboons that hunt in the lake.

 Fish eagles always know what's going on and want a piece of the action.

 They know that baboons hunt in packs and usually there are leftovers.

 Staying airborne puts him in pole position. (a position on the inside of the track in any race. 2. (in auto racing) a starting position on the inside of the front row. 3. an advantageous position.)

 With baboons attacking from every direction the flamingos have little chance.

 The pent-up aggression causes fights to break out.(1.confined; restrained; not vented or expressed; curbed)

 Exactly what the eagle was hoping for.

 Although he's a hunter, he's never too proud to scavenge.

 But two can play at the thieving game.

 A steppe eagle drops in, at 250 kilometers per hour.

 He sends it packing, but many more are waiting in the wings.

 Fish eagles are plucky birds, and don't give up their food easily.

 But, in the end, it's a numbers game.

 Beaten by overwhelming force, the fish eagle has barely had a mouthful.

 Vultures are used to competing for their meals.

 For a scavenger, it comes with the territory.

 But there is one place that usually gives enough to go round.

 The Grumeti river.

 All they have to do is wait for the conveyor belt of food to arrive.

 This river is a favourite drinking spot in the wildebeest migration.(gnu: 牛羚、角马)

 But it is also one of the most dangerous.

 The vulture waits as the crocodiles demonstrate their lethal skills.

 By the end of the killing spree, the crocs are full and there are carcasses to spare.

 But where there are big crocodiles, there are also little ones.

 And they have to practise somewhere.

 Even at this hallowed spot, there's no rest for the wicked.

 A vulture's life is a never-ending journey to find food.

 Among the hot springs and geysers of Lake Bogoria, the flamingos have finally found peace.

 But they must be on their guard.

 The fish eagle is still hungry.

 He looks for any breaks in the ranks.

 He can't afford to fail this time.

 Success at last.

 As ever, the marabou stork never misses a thing.

 He could spear the eagle with just one jab.

 It's David versus Goliath.

 Like all bullies, the marabou crumbles when challenged, pecking the dirt in frustration.

 At last, the fish eagle enjoys the sweet taste of success.

 The flamingos may have lost one of their number, but it's a small price to pay for staying in a pink paradise.

 With two million together in peak condition, they can take time out for dancing.

 True love blossoms as they mirror each other's actions perfectly and lifelong relationships are formed.

 Soon hundreds join the parade.

 Their synchronised dance is one of the most beautiful in the bird world.

 It happens when the birds are fit and truly happy.

 A prelude to breeding that occurs only in special years.

 For the flamingo, it's a fitting end to her journey.

 But the swallows have a long way to go.

 They have travelled 3,000 kilometers from South Africa to reach here, but they are still only halfway home.

 A hatch of midges will help power their journey onwards.

 It's a vital meal.

 The swallows still have to cross the Sahara.

 An area as big as the United States.

 The white storks choose a safer but longer route, one that avoids the Sahara altogether.

 They follow the life-giving waters of the Nile.

 The swallows rely on oases.

 Without them, they could never survive.

 Meanwhile, common cranes have joined the migration and are heading out of Africa towards Europe.

 It's a route that takes them over the Mediterranean Sea.

 The storks try to avoid the sea altogether.

 But things don't always go to plan.

 Thermals can't form over water, so the storks are heading for disaster.

 If a wing tip touches the water, they will fall in and drown.

 Next time, we will follow the storks' fate, as they try to reach their breeding grounds.

 On the wings of birds, we will discover the human and natural world of Europe as it has never been seen before.