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01:20White stalks.
01:21If you wanted to pick one bird as a representative of all the birds in the world,
01:26you could do worse than pick the white stalk.
01:29It's a marvellous flyer. It's an intrepid traveller.
01:33This pair will have come all the way from Africa to nest in this small town in Bavaria.
01:38They have complicated courtship and greeting rituals.
01:42And they're devoted parents.
01:44And just as they could stand for all the birds in the world,
01:47so this, a stalk's feather,
01:50could be seen as a key to everything that is most crucial about a bird.
01:55The feather is a marvellous aerofoil.
01:59Man has yet to invent anything that's as strong weight for weight.
02:04It's also an extremely efficient insulator, and that too is very important to the bird.
02:10And it's a very complicated structure.
02:13This feather has several hundred separate filaments on either side of the central quill.
02:19And they are held together to form one continuous surface by several hundred thousand microscopic hooks.
02:28The feather is the individual creation of the birds.
02:34No other kind of animal possesses a feather.
02:37And the oldest known feather in the world was discovered as a fossil in the rocks only a few miles from here in Bavaria.
02:46It's two and three-quarter inches long, preserved in miraculous detail,
02:52and to all intents and purposes it looks identical with a stalk feather.
02:57That feather had been found by men quarrying this limestone near the little town of Solenhofden.
03:24The stone had been laid down about 150 million years ago at the bottom of a shallow lagoon.
03:30And its fine, even texture made it ideal for use in lithographic printing.
03:36But that texture also makes it a superb preserver of fossils.
03:41The feather tantalised the world of science.
03:45What sort of creature could it possibly have come from?
03:48Well, immediately there was a huge search mounted in these quarries.
03:52And even now, it's almost impossible to resist the temptation of pulling down almost every boulder you see,
04:00and then opening it like a book to look at each unopened page to see whether maybe it contains yet another fossil.
04:12And after nearly a year, in 1861, in this very quarry, they found what they had been looking for.
04:22A skeleton, a foot or so long, surrounded by feathers.
04:27They called it Archaeopteryx, ancient bird.
04:31Its skull was missing, but then another complete skeleton was found.
04:36The creature had limbs of equal length, so that if it hadn't been for those feathers,
04:41it might have been taken for a four-legged runner, like a lizard.
04:46Its head, too, was very reptilian, with tiny teeth along its bony jaws.
04:52And the front limbs had three toes apiece, each toe ending with a claw.
05:02The tail was supported by a bony rod, an extension of the backbone running down the middle.
05:08But all around, there are the miraculously detailed impressions of feathers.
05:13In some places, it's even possible to see the filaments on either side of a central quill.
05:19So those front limbs with claws are not the legs of a lizard, but the wings of a bird.
05:27So perfect are these fossils that we can make a pretty confident reconstruction of the living animal.
05:33But could this, the earliest of birds, flap its wings?
05:38Its breastbone has no keel on it to carry large muscles,
05:41so its wingbeats at best could only have been very feeble.
05:45It probably depended, for the most part, on gliding.
05:48The long toes on its feet had a good grasp, both forwards and backwards,
05:55so that it would have had no difficulty in perching on branches.
05:59And those claws on its wings, doubtless helped it to steady itself as it clambered around.
06:05In all the world today, there is only one living creature that has claws on its wings.
06:11And this is it.
06:13This is the hoatzin.
06:18Not an adult bird, but a chick.
06:21And it only possesses claws on its wings for a week or so.
06:24But while it does, it gives a vivid hint of how the first birds may have moved about in their trees.
06:31Maybe the ancestors of Archaeopteryx took to the trees
06:50because hungry reptiles roamed below looking for a meal.
06:54The young hoatzin faces just such dangers today.
06:57For its home in the swamps of Venezuela is haunted by crocodiles and caiman.
07:03And reptiles very like them certainly prowled the swamps and forests 150 million years ago.
07:18Although the adult hoatzins don't have claws on their wings,
07:21they nevertheless still have a very reptilian look to them,
07:25with their glittering eyes surrounded with scaly skin and an odd, bristly crest.
07:31Nor do they seem to have totally mastered flight.
07:34They can only cover relatively short distances before they need a rest.
07:39In the branches, they use their wings to help them keep their balance.
07:44Nonetheless, they are true birds and very much better adapted for flying than Archaeopteryx ever was.
07:51Flyers must reduce their weight to a minimum and all birds today, including the hoatzin,
07:57have lost the bony tail of the reptile and have instead a lightweight tail constructed entirely of feathers.
08:04Weight has been reduced at the front end as well.
08:07Bony jaws and teeth are particularly heavy and no modern bird possesses them.
08:12Instead, they have beaks of keratin, the same horny substance as that from which feathers are made.
08:18Keratin is not only light and strong, but it can easily be moulded into a great variety of shapes
08:25and turned into the particular tool that a bird needs to gather its food.
08:31The hoatzin has an unusual diet.
08:36It uses its beak to pluck leaves, which it then regurgitates for its chick.
08:44Often the beak is elongated and used as a pair of forceps.
09:02The white stork has a medium-sized model for picking up frogs and little fish.
09:07Another stork, the shoebill, has a heavy-duty version for dragging lungfish from mud.
09:14And the crane, a short pair with which to pick up seeds and insects.
09:19The butchers among birds have turned their beaks into hooks with which to tear flesh.
09:25Vultures.
09:32The monkey-eating eagle from the Philippines.
09:43Others, like the scarlet ibis, have long probes that can pick out small invertebrates from their burrows.
09:55The beak of a spoonbill is not, in fact, a spoon, but a sieve, with which its owner collects small creatures from the water.
10:09The flamingo's bill is a filter pump.
10:12The tongue works like a piston, drawing water in and squirting it out several times a minute.
10:18Coarse hairs on the side of the bill prevent mud getting in,
10:21and hairs inside trap microscopic plants and animals.
10:28Pelicans.
10:34Some dive on shoals of fish.
10:37Others use their baggy bills as nets and go fishing in teams.
10:41Another fisherman.
11:00Little fish, it seems, are eager to swim into the shade.
11:04The black heron provides it with its wings,
11:06and then stabs with precision at any fish that's attracted to it.
11:12The beak is not only a feeding tool.
11:15It's also an essential instrument for keeping in trim those most valuable of a bird's possessions, its feathers.
11:22They need a lot of maintenance if they are to be kept in the best of condition,
11:25and the beak, even the biggest, is used with great delicacy to preen the feathers one by one,
11:33repairing any breaks in their veins by zipping up the hooks on the filaments.
11:37Storks, like most birds, have a preen gland on their rump.
11:59They collect oil from it with their beaks, and then use that to waterproof their feathers.
12:03Waterproofing is obviously particularly important for water birds,
12:12and water only flows off a duck's back because its feathers are well oiled.
12:17But being waterproof does cause problems.
12:33Below water, unwetted feathers hold air trapped between them, like a silver sheath.
12:37And that's very buoyant, so ducks and ducklings have to paddle very hard with their legs
12:43to prevent themselves from bobbing back to the surface.
12:45The business of getting the beak down into the mud of the bottom is made easier
12:55by having legs far back on the body near the tail.
13:02All the same, it's hard work.
13:05The business of getting the beak down into the mud of the bottom
13:10is made easier by having legs far back on the body near the tail.
13:15All the same, it's hard work.
13:17The business of getting the beak down into the air,
13:20I think it's hard work.
13:22It's a tricky part of the bridge to build up the tip of the air with.
13:25It's hard work, it's hard work.
13:27The business of getting the neck is hard to find them.
13:30It's hard work.
13:32It's hard work.
13:35The little bit of the shape of the neck is hard for you to find the neck.
13:37The kind of shape is hard work for you to find any more than an inch.
13:41The ounce of the dirt.
13:42The boiled rock is hard work for you to find the inner hair.
13:44As well as oiling their feathers, many birds, like the peacock, ruffle them in dust.
13:58The skin beneath the feathers must make a very attractive home for parasites like fleas and lice,
14:04and dust bathing is one way of getting rid of them.
14:07Another way is to enlist the help of other insects, ants.
14:11Many ants, when they're irritated, squirt acid, and that will shift most insect parasites.
14:20Jays and crows are particularly addicted to this habit.
14:23By spreading its wings, the bird makes it easier for angry ants to swarm all over its skin, between the feathers.
14:44And often the bird seems to enjoy the process so much that it goes into a kind of ecstasy.
14:50So, one way or another, birds go to a lot of trouble to keep their feathers in good condition.
15:15And in truth, their lives depend on them, and not only for support in the air.
15:20Birds are warm-blooded.
15:22They have to be to produce the energy they need for their very active lives.
15:26So, insulation for their bodies is essential, and nothing does it better than a coat of feathers.
15:32Only a bird, wrapped in a coat of fine feathers, can live in the coldest place on earth, the Antarctic ice cap, in winter.
15:51Some species of penguin survive temperatures of 40 degrees below freezing, and for weeks on end.
15:58The feathers of both adult and chick are specially adapted to provide warmth.
16:15They're very fine and grow in a thick mat.
16:18But the feathers of most birds have to serve another purpose as well.
16:22Flight.
16:22If beauty comes from perfection, if grace is a measure of skill,
16:29then a bird in the air must be among the loveliest sights in nature.
16:33Al silicon.
16:35Terrific.
16:40Than a bird.
16:43To be seen again.
16:44A bird.
16:48Okay.
16:50When you look at the land.
16:52Terns are among the most graceful of flyers,
17:17responding to every tiny variation in the wind currents
17:21with the subtlest adjustment to the contours of the tail and the wings.
17:51The tropic bird, by using updrafts and working hard,
17:55can hang in the air in order to display to its mate.
17:58Ocean-going birds, like the frigate, sail on long, thin wings,
18:03the best shape for efficient gliding.
18:07One of the most skilled gliders of all, the albatross,
18:14which beats up and down the ocean,
18:16supported by the lightest of breezes,
18:18with only the gentlest of flaps of its wings.
18:25The albatross, which beats up and down the ocean,
18:27supported by the lightest of breezes,
18:29with only the gentlest of flaps of its wings.
18:33But long wings for gliding flight don't make for easy landings.
18:52Having missed its touchdown, the booby has to labour to regain speed
19:12and avoid a stall and a crash.
19:28The frigate bird has similar problems, but solves them successfully.
19:33The booby has another try.
19:58There are helpful winds to be exploited over land as well as over the sea,
20:02and above wild mountainous country like the Grand Canyon,
20:06where the sun heats the naked rock,
20:08there are hot thermal currents that sweep up the cliff faces.
20:12So vultures can sail and soar with an economy that rivals that of the albatross.
20:27Such birds as these, sliding effortlessly through the air,
20:31can reach great speeds.
20:33But the airspeed record is held by a much smaller flyer, the swift.
20:38Here it is in slow motion.
20:42One species is said to reach speeds in level flight of 170 km an hour.
20:48The swift is the most aerial of birds,
20:51hardly ever alighting except to nest,
20:53mating and even sleeping on the wing,
20:55and every day flying up to 1,000 km a day to gather insects from the air.
21:02Other birds also feed on the wing,
21:04and just as ground feeders have beaks that are modified for their particular diets,
21:09so many of these flying hunters have beaks that are specially suited to their own particular techniques,
21:15and what's more, ones that require great acrobatic skill to manage properly.
21:22The skimmer has the oddest of beaks.
21:25It's the only bird with a lower mandible longer than the upper,
21:28and to use it requires perfect flight control.
21:32When the lower mandible strikes an object like a little fish,
21:42the beak automatically snaps shut.
21:47And some say that there's more to it than that.
21:52The furrow cut in the surface of the water sparkles and attracts surface-feeding fish.
21:57And having made one run, the skimmer often turns and flies back along exactly the same course,
22:03perhaps to collect anything that has taken the lure.
22:27In the Andes live other birds with superb aerial control and extraordinary beaks to manipulate.
22:42The tatura plant is rich in nectar, and hummingbirds are nectar addicts.
22:48But those with normal-sized bills can't reach the main supply at the top of the tubular blossoms,
22:53even when they cling to the flowers with their feet.
22:57The sapphire wing has a somewhat longer bill.
23:06But even this can't reach into the depths of the flowers.
23:14What is needed is this, the outsized beak of the sword-billed hummingbird
23:24that is longer than its entire body.
23:28The bird's flying control has to be total in order to manoeuvre this huge instrument, and it is.
23:34Slow motion shows how expert it is in keeping its bill perfectly steady in relation to the blossom,
23:40even while its body moves in all directions.
23:42Slowed down still further, you can see how the wings move in order to enable the bird to hang in the air.
23:59The bird tips its body vertically so that air currents from the wings are driven downwards.
24:05Each wing is so jointed that it beats in a figure of eight and produces lift on both the forward and the backward beat.
24:12Their arms are very short and close to the body, so these birds actually fly with their hands.
24:18So, with the help of their feathers, birds have mastered all the manoeuvres in the air.
24:39The stalk's wings carry it for thousands of miles up from Africa to northern Europe each spring to nest,
24:48often on exactly the same site that it's used many times before.
24:53The male usually arrives first, and he immediately proclaims his ownership of the site.
25:11The nest must be refurbished.
25:21No matter how big it is already, the bird seems to reckon that it will be improved with a few more sticks and a fresh lining.
25:31This display not only serves as a notice of possession, but as an invitation to a mate.
25:41Once the pair have come together, the ritual is carried out again and again, strengthening the bond between them.
25:49The sound of the bill clatter is an integral part of the display.
25:56The nightingale also needs a mate and a nesting site, but its feathers are drab, its habits retiring,
26:03and it claims them not with a dance and a clatter, but with a song.
26:08A song that penetrates the thickets in which it lives.
26:11A song, like bright feathers, conveys a thirst for the eyes.
26:16BIRDS CHIRP
26:37Song, like bright feathers, conveys a third message, identity.
26:43This is a relative of the nightingale, the black cat.
26:50He makes his species clear with that distinctive patch of black on his head,
26:54but he also produces a quite different and very characteristic song.
27:08The grasshopper warbler relies almost entirely on song.
27:12That's a rival singing, and he must answer.
27:15Music
27:20All right.
27:50This looks very like another grasshopper warbler, and most birdwatchers, and doubtless most birds, couldn't be quite sure that it isn't until it sings.
28:04It's a willow warbler.
28:07So, with song and dance, identities are established, territories claimed, and the pair bond made.
28:20All is now set for the business of reproduction.
28:23Feathers are particularly suited for display.
28:52They are light, they can be easily erected into great fans and crests, and some birds, like, for example, the cori-bustard, have exploited that potential to an extraordinary degree.
29:04When male meets male on the African plains, they argue over territory with feathers.
29:09The female great-bustard is neatly camouflaged and unobtrusive, but her mate inflates himself in the most spectacular fashion.
29:31But one family has excelled all others in the shape, the colour, the sheer beauty of their display feathers.
29:43They live in New Guinea, the birds of paradise.
29:46They live in New Guinea, the birds of paradise.
30:00They have a story with direction, and they live in the kingdom of paradise.
30:04They are always in our position, and they are always in the middle of the life of paradise.
30:09The superb bird not only has this iridescent shield on its chest,
30:31but on the nape of its neck, a roll of feathers that it can open into an umbrella.
30:36The six wired birds, and there are several kinds, carry half a dozen naked quills on
30:42their heads, each ending in a small black pennant.
30:46The males display on the ground, clearing special dancing floors which they tend every day, keeping
30:52them meticulously clean and tidy.
31:02The female has none of the splendour of the male.
31:05His life during the breeding season is devoted to dancing.
31:09The females tour the courts and eventually mate with one of these dandies.
31:14She rears the young entirely by herself while he continues to strut on his court.
31:20The magnificent bird sprouts two curving quills from its tail and has three capes on his shoulders,
31:25each of a different colour.
31:27He too displays on the ground and strips the leaves from the saplings so that he can dance
31:32in a pool of light.
31:36Other birds of paradise display up in the branches.
31:40The males don't acquire these plumes until they are several years old, and they molt them
31:45every year at the end of the breeding season, so that for much of the time they look very
31:49like their drab females.
31:51When they dress for the dance, however, they spend a lot of time grooming and preening themselves,
31:57lavishing as much care on their display feathers as they do on those more utilitarian ones on
32:03which they depend for flight.
32:18The females visit the display trees to select their partners, but the males display whether
32:23they're there or not.
32:42Each species, this is the lesser bird, has its own particular dance, its own characteristic
32:59way of showing off its finery to the best advantage.
33:12The emperor of Germany's bird begins with a throbbing fluffing up of the plumes beneath
33:17his wings, but has developed a most surprising climax to his performance.
33:40And Raj's bird throws his plumes over his back in a quivering fountain of red.
33:50But to me the most remarkable and thrilling display of all is that of the bluebird.
33:59And as he quivers and trembles, he sings as extraordinary and unbird-like a song as comes from the throat of any bird.
34:06And as he quivers and trembles, he sings as extraordinary and unbird-like a song as comes from the throat of any bird.
34:21And he's very
34:29The
34:44and these are some of the largest feathers in the world and surely among the most spectacular
35:04the peacock's feathers and there's still something of a mystery darwin himself confessed that he was
35:10baffled by the sheer perfection of such feathers as these where they really developed just to enable
35:17a peacock to compete in splendor with other peacocks or to impress the peahen there are a lot
35:23of people who think we've got some way to go before we know the full answer to questions like those
35:40and this is one characteristic of the reptiles that the birds never abandoned laying eggs in nests
35:51every other vertebrate group has some species that retain the eggs in the body and give birth
35:58to live young some fish do it some amphibians some reptiles and of course all mammals but there's not
36:04a single bird that does it and the reason is pretty obvious it would be a severe handicap for
36:11a bird to fly around with the weight of this in its body let alone the weight of a whole clutch for as
36:17long as it takes for it to hatch much better to lay it in a nest as soon as it forms but that of course
36:27makes the eggs very vulnerable and birds go to a lot of trouble to protect their eggs and their nests
36:34the peahen makes a straightforward nest in a secluded place in the undergrowth and she forgoes the
36:46attention-catching display feathers of her mate so that she's well camouflaged
36:50several water birds including the giant coot in Chile lay their eggs on floating islands of vegetation
37:00well beyond the reach of most robbers
37:03other birds these are oropendulas from south america achieve inaccessibility by weaving bottle-shaped nests at the end of branches
37:28on the pampas of south america the oven bird builds a nest of mud it's shaped like a local
37:37oven and when it's finished it will have a tiny entrance hole which effectively foils most intruders
37:43long-tailed tits weave a domed nest of cobwebs and moss fill the inside with carefully collected
37:56downy feathers and camouflage the outside with bits of lichen the sparrow is one of the untidiest of
38:05builders which will make use of any sticks around including those that are being used by others for
38:10in Iceland there are great colonies of arctic terns shores where they nest provide very little building material and no cover whatsoever so they largely dispense with nests and do their best to deflect intruders by diving at them
38:17in Iceland there are great colonies of arctic terns
38:24in Iceland there are great colonies of arctic terns shores where they nest provide very little building material and no cover whatsoever so they largely dispense with nests and do their best to deflect intruders by diving at them
38:36the safety of their eggs depends largely on their camouflage shells inside the eggs the developing chicks like their parents have warm blood and if they get chilled they die
38:53the eider duck which also breeds in Iceland develops special downy feathers on its breast and with them builds one of the warmest of all nests
39:08man himself has yet to devise anything more luxuriously warming than eider down
39:15the colour of birds eggs varies hugely and so does their size this is the smallest of all laid by a hummingbird and no bigger than a pea and this is the biggest
39:28is probably the largest egg that it's possible to have because obviously the shell has to be pretty thick to hold two gallons of liquid and if it were any bigger it might have to be so thick
39:44that the young chick inside would be unable to hammer its way out
39:48this egg was found down here in these thorn forests of southern Madagascar
39:53and it was laid by a giant flightless bird one of the biggest bird that's ever existed
39:59rather like the ostrich standing about ten feet tall
40:03it was called the elephant bird or eepionis and it seems that it was alive up to about two or three hundred years ago
40:12but now alas it's certainly extinct
40:18parent birds have to labour hard keeping their eggs warm in cold climates and in warm ones protecting them from the sun so that they don't overheat
40:27and when the eggs hatch they must collect food to supply their growing and perpetually hungry young
40:33soon these young stalks will fly but where exactly will they go to find out stalk chicks all over Europe have been ringed
40:48the rings are light and of aluminium and carry an address so that anyone finding the bird in mum
41:06months to come will know where it was hatched and reared
41:21the young stalks flap their wings exercising the muscles that will have to sustain them in the air while their parents continue to collect daily supplies of frogs and fish
41:34and then after about sixty days both young and parents depart
41:49the chicks miraculously having most of the skills of flying the very first time they launch into the air
41:55some surprising results have come from ringing stalks in this town in southern Germany
42:12many of the birds make their way to Africa going east around the Mediterranean by way of Istanbul
42:17but the town lies on a fork in the migration route and others go west across the straits of Gibraltar
42:25and as they head south they become more and more concentrated
42:29these immense transcontinental journeys make great demands on a bird's strength
42:34many rely on the upward rising thermal currents produced when the sun heats the land
42:40for if you can get high you can glide effortlessly for great distances
42:47thermals don't occur over the sea so the migrants gain as much height as they possibly can
42:52before embarking on a crossing of the Mediterranean
42:55and near both Gibraltar and Istanbul
42:58they soar round and round in the up currents climbing higher and higher
43:03those that arrive at the coast in the evening roost
43:07for after the sun has gone down there are no more thermals
43:10it's better for them to wait until morning
43:13so the straits of Gibraltar each spring and autumn
43:32are visited by many thousands of bird travelers on their way to or from Africa
43:37the nearby mountains and the rock itself warming in the Mediterranean sun
43:42produce particularly strong up currents of air
43:45and Africa lies only a few kilometers away across the strait
43:49a kestrel taking a rest on its long journey
43:55honey buzzards from much of Europe congregate here
44:00and share the thermals with the stalks
44:03these great invasions of tourists often infuriate the local residents
44:23sometimes on dull days the short-toed eagles can't get the lift they need for launching off to Africa
44:29and fly around Gibraltar Harbour
44:32the local gulls don't care for this kind of intrusion
44:35and mob them and sometimes even drive them down into the water
44:38from which they can't take off again
44:40just another hazard in the risky business of migration
44:44a black kite on its way back to Africa after breeding in Europe
44:56September in Gibraltar is a marvelous place for the bird watcher
45:00as travelers congregate at this international crossroads of migration routes
45:05and one of the best places to watch is from the very top of the rock itself
45:09it's coming to the end of the day and it's been a good one for the migrants
45:17parties of big birds 30 40 50 strong have been passing the rock
45:22gathering to get one last lift from a thermal in Europe
45:26so that they can gain altitude and glide down across the straits to Africa 12 miles away
45:32but how did they find their way here
45:35well some undoubtedly use geographical landmarks
45:39they come along the coast
45:41others follow prominent river valleys
45:44but that can't be all there is to it
45:46because young birds that have never made the journey
45:49can manage to do so by themselves
45:51so presumably they must have some kind of inherited map in their minds
45:57other birds manage to use the sun in some way
46:01because they can cross large expenses of sea and even featureless land
46:06but the sun has one major drawback as a navigational aid
46:10it moves so if you want to find your way by it
46:13you have to know what the time is
46:15so those birds presumably must also have a clock in their minds
46:20but in the evening of course the sun goes down it gets dark
46:25and you may no longer be able to see geographical landmarks
46:29what happens then?
46:33the answer can be found here in the air traffic control tower at the rock
46:38Gibraltar of course is of great strategic importance in the defence of Western Europe
46:42and close watch is kept by radar of all aircraft movements around it
46:47but radar can show up flocks of birds just as it can show up aircraft
46:52and in the autumn and in the spring
46:54the information that can come from these screens
46:57about what goes on in the skies at night is very spectacular indeed
47:05a few hours of an autumn night can be condensed into a few seconds
47:09the numbers of birds crossing the straits of Gibraltar into North Africa
47:12can be estimated from the massive black dots moving southwest
47:17on this night up to 200,000 birds at one time are represented on the screen
47:23and it's estimated that 5,000 million cross the whole Mediterranean each autumn
47:32how do they find their way?
47:34well some birds seem to be able to fly by the stars
47:38because if you release them in a planetarium where the artificial stars have been twisted around
47:44they fly by way of those
47:46other birds apparently are sensitive to electromagnetic waves
47:51so that it appears that a bird not only has to have a map of the land
47:55and a star chart and a clock
47:57but also a compass in its mind
47:59but the fact of the matter is
48:01there's still a very great deal that we don't know about bird navigation
48:05Gibraltar is only a halfway stage for most migrants
48:10Arctic terns hatched in Iceland in July are here in September
48:16but they still have got 10,000 kilometers to go before they reach their destination
48:22shearwaters move in a different direction
48:25migrating east and west between the Mediterranean and the Atlantic
48:29they're great travelers
48:30one returned to its nest in Wales crossing the Atlantic in 12 days
48:39this Arctic tern has now reached the southern tip of South America
48:43having left the Arctic at the end of its summer when the sun never set
48:47it's flying to the Antarctic summer
48:49so it sees more daylight than any other living creature
48:53the African plains are the target for the stalks
49:00and by the end of September
49:02they're feeding among game
49:04just as they did among herds of dairy cows
49:06only a few weeks earlier
49:09so flight, the bird's supreme achievement
49:12has carried them not only to all parts of the world
49:15but has made them into the greatest of all animal travelers
49:18and yet, most surprisingly, some species have abandoned it
49:23there's no doubt that the ostrich's ancestors could fly
49:26its body still retains many of the adaptations for flight
49:29a beak instead of heavy teeth and jaws
49:32and feathers on its wings that sprout in patterns needed for flight
49:36but now they're used only for display
49:39since the feathers need no longer support the bird in the air
49:57the hooks on the filaments have disappeared
50:00and the feathers have a soft fluffiness
50:02that is found to be irresistibly alluring by other creatures
50:06as well as female ostriches
50:36but why should the ancestral ostrich have given up flight?
50:47well, flying is a very demanding business
50:50if there are no ferocious predators to drive birds into the air
50:54it's a much easier option to remain on the ground
50:57that often happens today on islands
51:00and it happened once to the ancestral ostriches
51:03ostriches
51:10ostriches belong to one of the most ancient of the bird families
51:16when they first appeared about 50 million years ago
51:20the dinosaurs and the other giant reptiles
51:23had only recently vanished
51:25and the position of ruler of the world was vacant
51:28and it seems that birds like that made a bid for it
51:34there was one great flightless bird in North America
51:37that had a huge murderous bill
51:39that looked as though it could kill any animal that was around at the time
51:43and even looking at those ostriches
51:46it's not difficult to imagine how dangerous and frightening they might be
51:51if they suddenly acquired a taste for red meat
51:55they could certainly outrun me
51:57and one kick from those legs could knock me over and rip me open
52:01but that bid for supremacy by the birds failed
52:05there was another unobtrusive little creature around at the time
52:09that also had warm blood
52:11but it was descended from a different group of reptiles than the birds
52:15and it insulated its body not with feathers but with fur
52:20that was the creature whose descendants were to inherit the earth
52:24that was the first mammal
52:28and the ship's taking records
52:29and the Kimoso birds
52:30to find different planets
52:31and its own lilimbs
52:33that were to aristotle
52:34and the drivers of the birds
52:35who actually saw it
52:36but these are the ones that were to be
52:37the força of the birds
52:38who wanted to get the birds
52:39as they were to take off
52:40and how did the birds
52:41where the birds live
52:43and the birds live
52:45are these birds
52:46that would be very special
52:47that birds of the birds
52:48that were never as though
52:50and they were to be
52:51there were too many creatures
52:51that were really
52:52that would be a sort of
52:54in the middle of the birds
52:55that were catching the birds
52:56of a jungle
52:58ORGAN PLAYS
53:28ORGAN PLAYS
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