The Life of Birds - Limits of Endurance
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00:30The desolate wastes of the Antarctic, so cold that insects would freeze solid.
00:45Volcanic springs in Africa, spouting water so hot and corrosive that it will strip skin
00:50from flesh.
00:54The waterless deserts of the tropics, hundreds of square miles of baking sand.
01:04The earth can be an inhospitable place, yet birds of some kind manage somehow to endure
01:11and survive all its privations.
01:13Indeed, there is scarcely a corner of the globe that birds have not colonized.
01:28Sandgrasses live in the sandy deserts of Africa, as barren a landscape as you can imagine.
01:34Yet hidden in these sands are tiny seeds.
01:38They were shed by plants months or years ago after a storm briefly dampened the desert.
01:44The sandgrass, by searching incessantly, manage to pick out several thousand every day.
01:53But they have to drink.
01:54Water holes are few and far between in this desert, and some birds may have to fly for
01:59as much as 50 miles before they find one.
02:03And when they get there, all it is is a little puddle like this one in front of me.
02:17After such a long fight, their thirst is huge.
02:42But some must do more than satisfy their own needs.
02:57They have left behind them away in the desert their newly hatched chicks.
03:05Chicks can't fly, but they too must have water, and the males will take it to them.
03:12They can't carry it in their crops, they'll need all that water to sustain themselves.
03:17But they have extra tanks.
03:21Their breast feathers have a special adaptation.
03:24They're covered on their inner sides with a mat of filaments so fine that they absorb
03:29water like blotting paper, and then they're off again on the long return flight.
03:47A female is waiting for her mate.
03:50It's roastingly hot, and with her are her chicks.
03:57Here he comes, and the female makes way for him.
04:11While the last chick struggles from its shell, the others cluster around and suck from his
04:17breast for all the world like puppies or kittens.
04:25So one comparatively small adaptation of its feathers has enabled the sandgrouse to
04:30colonize a corner of the world closed to others.
04:41The ground in the wake of one of the bushfires that regularly sweep across the grasslands
04:45of Africa seems initially just as parched as its deserts, yet the courser, a relative
04:52of the plovers, is a nomad who actually seeks it out.
04:57Insects killed by the smoke and flames are easily collected, so it has some attractions.
05:02Yet it is also here that it chooses to nest.
05:12This must be a long-standing habit, for its eggs are camouflaged to match the incinerated
05:18earth.
05:20Once all the scrub has been cleared by fire, the bird has the advantage of being able to
05:24see approaching predators.
05:31Dawn on the shores of the Persian Gulf, and crab plovers, having fed on the edge of the
05:45sea, come back to their breeding grounds.
05:49It will soon be so hot that the sand will be painful to touch.
05:57Yet this is where the crab plovers choose to nest.
06:07Every other plover in the world lays its eggs in a simple scrape on the ground, but not
06:12these.
06:16They, in spite of their unsuitably long legs, have learned how to become borrowers.
06:21They've discovered that only a few inches below the surface, the sand is wonderfully
06:25cool.
06:26There, a bird can sit on its eggs in comfort throughout the crushing heat of the day.
06:37To feed, the plovers have to go down to the edge of the sea.
06:43There, they can keep cool by bathing.
07:02The African rift valley offers no such relief.
07:07This steaming hot water comes from volcanic springs, and is so loaded with soda that around
07:13the margins of the lake it solidifies into white curds.
07:17Yet flamingos come here in thousands.
07:26The attraction?
07:28The salty, tepid water is full of algae and small crustaceans, which the birds can collect
07:33using their specialized beaks like filter pumps.
07:43The fact that so few creatures can tolerate these conditions means that any animal that
07:48can has the place to itself, and so can proliferate in vast numbers.
07:54That applies to the crustaceans and the algae in the water, and also to the birds that feed
07:59on them.
08:02For the birds, there is an additional attraction.
08:06The soda-rich waters are so caustic that hunters such as hyenas, lions or smaller cats won't
08:12made through them, so the center of the lake is one of the safest places for a nest.
08:27The flamingos pile the mud into mounds just high enough to be clear of any salt spray
08:32blown by the wind.
08:33That, if it caked the eggs, would kill them.
08:42The heat is so extreme, the congealed soda so caustic, that sometimes a whole generation
08:49is lost.
08:50Nonetheless, the success rate is still sufficient to maintain the size of the flocks.
09:06This white desert is also hostile to life, but for a very different reason.
09:15The crust that I'm walking on is not soda, it's snow and ice, and that too causes huge
09:23difficulties for birds.
09:27Here in the Arctic during the winter, such things as are edible are locked away beneath
09:32the snow and ice.
09:34Nonetheless, a few birds manage to survive through this bleak season, provided they get
09:39help from polar bears.
09:54The bears will eat almost every part of the seal, their staple diet, but they leave enough
10:00from their kills to provide scavenging gulls with a meal.
10:24In summer, on the tundra, it's warm enough for plants to grow in the lakes.
10:29Here, spectacled eider duck swim and dive to collect insect larvae and worms from the
10:35muddy bottom.
10:51But when winter comes, the lakes freeze and then the ducks vanish.
10:56Until very recently, no one knew where they went.
10:59The answer was found in 1995.
11:03Hundreds of miles from the coast, they gather together on the surface of the sea, surrounded
11:08by ice.
11:16There are no more than half a dozen such assemblies, and between them they contain the entire world
11:22population of the spectacled eider.
11:37The birds are so tightly packed and so continuously on the move that within their huge pond, the
11:43water does not freeze over.
11:46They can dive to collect food from the bottom of the Arctic Ocean 200 feet below, food that
11:52would otherwise be denied to them by the sea ice.
12:02In the Antarctic, at the other end of the globe, the winter can be even more severe.
12:08Temperatures can fall to 80 degrees below zero, and the gales blow at over 100 miles
12:13an hour.
12:14Yet this is the time the biggest of all penguins, the emperors, have to breed.
12:25Having mated at the beginning of the winter, the females return to the sea, leaving the
12:30eggs with the males, who hold them on top of their feet to keep them off the ice.
12:40Ponds are so big that there is not time in the short Antarctic summer for the chicks
12:45to grow into seagoing adults, so breeding must start before the winter sets in.
12:51The males cannot feed for four months, then the females will return, allowing the males
13:09to go down to the sea for a meal.
13:19Meanwhile, in the continuous darkness of midwinter, broken only by the southern lights, all the
13:25male emperors can do is endure.
13:32The darkness perhaps doesn't trouble them unduly.
13:36Birds, after all, don't fly, but most birds do, and they rely on their sight in order
13:41to navigate.
13:42So, for them, darkness is a major problem, and no darkness is more complete than in a
13:49cave.
13:50This is the Caripe Cavern in Venezuela, and here there is no natural light whatsoever.
14:00And yet, as I can hear from this deafening chorus of calls, there's a huge population
14:06of birds here.
14:07How can they see the sun?
14:10Well, we have with us some very, very dim lights and an extremely sensitive low-light
14:16camera.
14:17So, if I turn this out, I can't see anything at all, and presumably the birds can't either,
14:26but hopefully you can.
14:31These are oilbirds.
14:33They're related to nightjars and, like them, have large eyes that help them fly by the
14:38light of the moon and stars, but in the depths of caves, even eyes like this are of no help.
14:45Instead, the birds navigate by sound.
14:49Their raucous social calls are augmented by high-pitched rattling sounds.
14:54The echoes produced by these enable the birds to visualize their surroundings so well that
15:00they can unfailingly find their own nest.
15:08In the evening, they fly out into the comparative brightness of the starry sky to feed.
15:17They seek out the fruit of palms and laurels, which have a strong fragrance, so the oilbirds
15:22are able to find them by smell.
15:30The birds are now in no danger of being attacked by hawks, as they would have been if they
15:35had not spent the day in the safety of their caves.
15:57So all over the world, birds, by changing their habits or adapting their anatomy, manage
16:03to survive in the most hostile of places.
16:08A century ago, a completely new kind of environment appeared on Earth.
16:13Nothing like it had faced the birds before in their entire 200 million years' history.
16:20Yet some species began to adapt to it almost immediately.
16:24This is it, the modern city.
16:29Sao Paulo in Brazil, a wilderness of glass and brick, concrete and steel, and circling
16:36among the skyscrapers, black vultures.
16:40There are plenty of ledges on these man-made cliffs to serve as nest sites, and the vultures
16:46have little hesitation in using them.
17:06This devoted parent has brought back a cropload to feed its chicks.
17:32The adults have little difficulty in finding all the food they need for themselves and
17:37their young.
17:41There is literally tons of it around.
18:01A short flight away on the outskirts of the city, the rotting leftovers of a million meals
18:07are dumped daily, mixed with inedible refuse of all kinds, some of it actively poisonous.
18:15Not many birds have either the temperament to tolerate such places or the digestion to
18:20cope with such food.
18:25Those that have swarm in huge numbers, like flamingos on an African soda lake.
18:44In the same way, when farmers bring industrial methods into agriculture and devote huge fields
18:50to raising just one particular crop, and it particularly suits the taste of one particular
18:56bird, that bird will turn up in huge numbers to feast on it.
19:03Waxwings.
19:11They love these blueberries, ripening in plantations in Florida, so they come in thousands to collect
19:17them.
19:18If these assemblies reach plague proportions, then that is no more than a reflection of
19:23the intensive way in which man grows his crops.
19:29Few other birds can manage to eat these large cultivated blueberries, and indeed even waxwings
19:34sometimes have a little trouble in doing so.
19:52Crows have become highly skilled at making a living in these new urban environments.
19:57In this Japanese city, they have devised a way of eating a food that normally they can't
20:04eat.
20:23Dropping a nut from a great height onto a hard road does sometimes crack it, but some
20:28nuts are particularly tough.
20:32So the crows have devised a better way.
20:42Drop it among the traffic.
20:59The problem now is collecting the bits without getting run over.
21:10So some birds have refined their technique.
21:14They station themselves beside pedestrian crossings.
21:33Wait for the lights to stop the traffic.
21:47Then collect your cracked nut in safety.
22:08City life may offer birds attractions that are rather less obvious than just food.
22:13This is the centre of Glasgow, five o'clock on an autumn evening.
22:18For half an hour, thousands of starlings put on a spectacular display of formation flying
22:25over the darkening city.
22:32Why they do this, we don't really know.
22:35Maybe it is to get to know one another, creating some kind of team spirit, for they tend to
22:40spend the winter in parties.
22:42Maybe it's because there's safety in numbers when trying to avoid predators such as hawks.
22:51When it's too dark for aerobatics, they come in to roost.
22:57Such assemblies may be information centres.
23:00Birds that fed well today will head back tomorrow to where they know there is food, and those
23:05that are hungry will follow them.
23:08Here in Europe, towns are also attractive because it's a little warmer than out in
23:12the countryside.
23:19You might think that this is just about the last place that a bird or any other animal
23:25would choose to sleep.
23:27This is an oil refinery on the banks of the Amazon River in central Brazil.
23:33Just across the water, there's lovely virgin rainforests, yet here, well, just look and
23:41listen.
23:46A fine mist of aquid droplets stings your eyes.
23:50The noise hurts your ears.
23:55Yet promptly, at five minutes past six o'clock every evening, there is an invasion.
24:11These are small martins.
24:12Stay still and they will settle within inches of you.
24:23Why they come here in such numbers is a mystery.
24:27It can hardly be that they seek warmth in this muggy, tropical atmosphere of central
24:31Brazil.
24:33They don't feed here.
24:35Perhaps it's because there are fewer hawks around to harry them than in the forest.
24:42But whatever the reason, come they do.
24:48In March, however, many of them will migrate north to the United States, and there they
24:53take up residence in very different homes.
24:57Hurry up, we're moving out.
25:02Okay.
25:03Smells great.
25:04A small, lakeside town in Pennsylvania.
25:21This luxury tower block has accommodation for over 40 adults and 200 youngsters.
25:44Each apartment has all modern conveniences.
25:47It can be wound down regularly by the local people, and the shelf brought out to make
25:54sure that the young are fit and don't need any help with their housekeeping.
25:59In fact, these apartments are so luxurious that these days purple martins don't nest
26:05in natural sites anymore.
26:08The purple martin has become totally dependent on human beings.
26:31It's said that the tradition was started by the people native to this part of North America,
26:36Choctaw and Chickasaw Indians, who were glad to see the birds when they arrived each spring
26:42and hung out gourds to encourage them to nest around their settlements.
26:46Today, over a million people in the United States offer hospitality to purple martins
26:53in this way.
26:57It seems that those of us who live in towns and cities feel increasingly cut off from
27:02the natural world that lies beyond our buildings, and so we treasure any contact we can find
27:07with wild creatures.
27:09Certainly, an affection for birds is shared by all kinds and conditions of people all
27:15over the world.
27:25In Arizona, Jesse Hendricks is particularly devoted to hummingbirds.
27:38His home lies on the migration routes of several species.
27:43The black-chinned is one of the most common.
27:45In spring, they travel up from Mexico on their way to nest as far north as Montana and British
27:51Columbia.
27:53Then in autumn, he sees them again on their way back to their winter quarters in the warmth
27:58of the south.
28:09Some of them have been fitted with leg rings, so he knows that the same birds visit him
28:14each year to drink from the same feeder.
28:17It's possible that many now vary their routes to make sure that they pay a call at such
28:23a reliable restaurant.
28:31At the height of the migration, he may be visited in a single day by about 9,000 different
28:38birds, and every day he provides his customers with over 13 gallons of sugar water.
28:46Birds like these must surely make the difference between life and death for many of the little
28:51rufous hummingbirds, which, on leaving Jesse's fuel station, have still to tackle the last
28:56stage of their 2,000-mile migration across the Bay of Mexico in one single 600-mile non-stop
29:04flight.
29:11The very regularity and predictability of birds can be part of their appeal.
29:21On Phillip Island near Melbourne, Australia, people come from all over the continent to
29:26watch a regular evening parade, little penguins, the smallest of the family.
29:56They fish for pilchards and anchovies out at sea during the day, and every evening come
30:05ashore together to return to their nest burrows, following paths that have probably been in
30:10use for thousands of years.
30:26Scientists started to tag them back in 1968.
30:30It's the longest-running bird study in the whole of Australia, so by now they are well
30:35used to being stared at.
30:50Human beings over the last century have built houses for themselves along the penguins'
30:54beach, but that hasn't deterred the birds.
31:10Two half-grown chicks are awaiting their evening meal, and the human residents are only too
31:16delighted to have such engaging lodgers with regular habits living beneath their front
31:21doorstep.
31:48Australia's impact on the bird world, however, has not always been so helpful.
31:54Birds reached all the islands of the Pacific a very long time before people did.
31:59Small birds, such as white-eyes, are not very powerful flyers, but they probably made the
32:04sea crossings inadvertently carried by storms.
32:10Once on land, they and others, like fantails, found insects to eat which doubtless had made
32:16the journey in the same sort of way.
32:21Honey-eaters found plants in bloom from which they could drink nectar.
32:34And pigeons found fruit.
32:51But when people sailed across the sea, they brought animals that by themselves could never
32:56have made the journey.
32:59This is the small island of Guam that, during the Second World War, became a major military
33:05base.
33:08Sometime in the 1940s, brown tree snakes from New Guinea appeared here, brought accidentally
33:14by ships.
33:16Tree snakes hunt birds, and Guam's white-eyes, flycatchers and fantails, having no experience
33:23of predators, had no defence against them.
33:40Today Guam is an island without birds.
33:44Species that evolved here and differed from any elsewhere have now gone for good.
33:49Insects and spiders, without birds to keep their numbers in check, have proliferated.
33:55And the forests have fallen totally silent.
34:11These New Zealand forests have also been invaded by foreigners, foreigners that have caused
34:17great problems for the local birds, and in particular the caca, the local parrot.
34:22These invaders are surprisingly very small.
34:25They're European wasps, but their effects have been devastating.
34:37Cacas eat a great deal of vegetable food, fruit and seeds and nectar.
34:44But they also feast on honeydew, a sticky fluid excreted by insects that live beneath
34:50the bark of these trees, drinking sap.
34:53Female cacas rely on this high-energy food to bring them into breeding condition.
35:04But the European wasps found honeydew much to their taste as well.
35:12The cacas are unable to compete, and they're already under severe attack from entities
35:17predators such as stoats.
35:29These latest insect invaders may well be the final competitors that eliminate the caca
35:34from these forests.
35:37But the greatest destruction of the world's birds has been inflicted by human beings.
35:44The huia, which once lived in New Zealand's woodlands, was hunted precisely because it
35:49was rare and was finally totally gone in 1907.
35:54The great auk, a giant flightless relation of the razor bill that lived in the islands
35:59of the North Atlantic, was hunted and exterminated by the middle of the 19th century.
36:06The dodo, a pigeon that's safe in its island sanctuary of Mauritius, also evolved into
36:11a flightless giant, was easy prey for hungry sailors.
36:16They exterminated it by the middle of the 17th century, less than 200 years after men
36:21had first set foot on their island.
36:26It's not only on islands that birds are vulnerable to changes brought by humanity.
36:30150 years ago, prairies like this in the United States were home to flocks of birds 2,000
36:37to 3,000 million strong.
36:40They were so big they darkened the skies and took two or three days to pass.
36:46They were what was probably the most numerous bird that has ever existed on earth, passenger
36:53pigeons.
36:57Their numbers were so astronomic that no-one considered them as anything but pests, nor
37:02could imagine that they would ever be in danger of extinction.
37:06But a combination of hunting and changes to the landscape brought by farming destroyed
37:10them.
37:12The last wild passenger pigeon was sighted in 1889, and the last survivor of all, a lonely
37:20female called Martha, died in Cincinnati Zoo in 1914.
37:27Birds are still being slaughtered in huge numbers, even today, particularly when there
37:32are economic reasons for doing so.
37:37Dickcissels in Venezuela also swarm in flocks millions strong.
37:42The whole world's population comes here in winter, and they sometimes roost in only three
37:47or four sites.
37:49Should anything happen to those sites, the dickcissels could go the same way as the passenger
37:54pigeon, and they are a very serious pest.
38:02Farmers know how to deal with insect pests.
38:12They spray them with poisons.
38:20So the same technique is sometimes used against dickcissels, in spite of the fact that it's
38:25against the law.
38:29The birds, recorded here by amateur video, take several days to die.
38:37Yet humanity, so often in the past the mindless and merciless exterminator of birds, can sometimes
38:44become their guardians.
38:48Here in a remote part of Tasmania, a mining family has become the saviour of the orange-bellied
38:55parrot.
38:57For years, they've been putting out food daily on a bird table, and these parrots became
39:02their best customers.
39:06A century ago, there were certainly many thousands of this bird here, and in Southeast Australia.
39:12But in the 1940s, they began to decline.
39:16The cause was probably competition from introduced seed eaters, such as sparrows, goldfinches
39:21and greenfinches.
39:23Furthermore, 70% of their mainland habitat was destroyed.
39:28European cats living wild in the bush also took their toll.
39:33Now not more than 200 survive, and nearly all of them are here during the nesting season.
39:40The area is very isolated, but bird-watching enthusiasts are very enthusiastic.
39:57They come not only from mainland Australia, but from all over the world to see these rarities.
40:05A special observatory has been built for them.
40:21And special nest boxes within binocular range have been put up for the parrots.
40:32So although the orange-bellied parrot is still few in number, and therefore a very
40:37rare bird, it's seen by thousands, and for the moment at least, seems safe in its remote
40:44sanctuary.
40:53This kestrel comes from Mauritius, the scene of one of mankind's earliest annihilations
40:59of the dodo.
41:01In 1974, only four known individuals survived.
41:06Today there are 540 on the island.
41:11They were saved by conservationists, who took young from the nests and reared them by hand,
41:17so allowing the adults to lay again.
41:19Today each nest is still being carefully monitored.
41:40The bird is now totally self-sufficient in the wild.
41:44Just two free-flying pairs are given extra food as part of a long-term study.
41:58The present population is now just about as many as the island can sustain.
42:11The Mauritian pink pigeon was actually thought to be totally extinct until a small colony
42:16was found in the mountains.
42:19But that dwindled to just nine known individuals.
42:25They too were persuaded to breed in captivity.
42:31The young are taken from nests and given to Barbary doves to rear, so releasing the adults
42:37to breed again.
42:45Now pink pigeons are being released in three different parts of Mauritius.
43:11Breeding programmes have also been started to help these new populations establish themselves.
43:30Today the birds are breeding regularly, and the population has risen from nine to over
43:36300 in just seven years.
43:45The Mauritian echo parakeet was once the world's rarest parrot.
43:50Now using similar captive breeding techniques, there are 20 in captivity and 80 in the wild.
44:05The island of Mauritius, once a black name in the history of humanity's relationship
44:10with birds, has become one of the showplaces of species conservation.
44:34In West Africa, in Cameroon, villagers celebrate the forest beside which they live, and in
44:39particular one of its birds, Bannerman's turaco.
44:52Many of the creatures of the forest, such as the elephant that also figure in this celebration,
44:57have long since disappeared.
45:01The turaco, however, still survives, though in the whole of this forest there are only
45:06about 4,000 pairs, and it lives nowhere else.
45:19For decades, the forest has been felled to make way for fields in which the people can
45:24grow their food.
45:25It's now only half the size it was 30 years ago, yet the people also know that they depend
45:34on the forest for water and firewood, for medicine and for meat, so now a balance has
45:41been struck.
45:46The traditional beliefs of the people have been harnessed to come to the forest's defence.
45:52The masked figure of Mabu, their spirit guardian, accompanied by the village elders, regularly
45:58patrols the margins of the forest.
46:01Stakes are planted to mark the point beyond which no tree may be felled.
46:07The turaco has become a symbol of the villagers' regard for their environment.
46:14And Mabu is now in league with international bird conservation bodies, who are also concerned
46:20about the survival of Bannerman's turaco.
46:33In North America, there are other masquerades to protect a bird that is even rarer than
46:38the turaco.
46:39A hooping crane chick learns to feed, encouraged by the gestures and calls of its human foster
46:46parents.
46:50In 1945, only 16 hooping cranes existed.
46:55Today there are 300, thanks to captive breeding and the patient rearing of chicks by hand.
47:04And this is surely one of the most extraordinary hand-rearing devices yet invented, a hooping
47:12crane adult hand-gloved puppet with a trigger inside so that I can operate the beak.
47:19I'm speaking quietly because behind each one of these doors, there is a hooping crane
47:25chick.
47:26And it's very important that they don't get used to the sound of human voices at this
47:31early stage in their lives.
47:33It's even more important, of course, that they don't see human beings, which is why
47:37they are fed with this glove puppet.
47:49Here at the International Crane Foundation in Wisconsin, they believe that were the chicks
47:54to be fed by humans directly and visibly, they would risk becoming humanised so that
48:00when they became adult, they wouldn't be able to breed with their own kind.
48:17As they grow, the hoopers lose all their brown plumage and replace it with white feathers.
48:25They must now learn how to use them in flight.
48:42And once again, they have to be shown the sort of thing they must do.
48:56Away to the west in Idaho, a farmer with a passion for cranes, Kent Clegg, has also been
49:02rearing a small group of hooper chicks.
49:05He has a mechanised way of persuading his little flock to fly.
49:12He's reared them in a quite different way, initially in small groups, which he believes
49:16will avoid humanising problems.
49:19He then taught them to follow him.
49:22Now he's put them together with the young of a commoner, smaller species, sandhill cranes.
49:27They are the all brown ones.
49:35And so the little mixed flock has become confident in the air.
50:35There's one further problem.
50:58Hooping cranes are migratory.
51:00In the past, some used to overwinter in the United States, but many in the autumn would
51:05fly south to New Mexico.
51:08If these birds were to remain free, they might try to do the same thing.
51:13But how would they know which way to go without their parents to guide them?
51:16And how would they find somewhere safe to feed when they got there?
51:20Well, that problem is being tackled too.
51:35Bent Clegg is planning to lead them there himself in his microlight.
52:25Birds were flying from continent to continent long before we were.
52:29They reached the coldest place on earth, Antarctica, long before we did.
52:34They can survive in the hottest of deserts.
52:37Some can remain on the wing for years at a time.
52:40They can girdle the globe.
52:42Now we have taken over the earth and the sea and the sky.
52:48But with skill and care and knowledge, we can ensure that there is still a place on
52:54earth for birds in all their beauty and variety, if we want to, and surely we should.