0:00:54 > 0:00:57Blue water covers most of our planet,
0:00:57 > 0:01:00but in it are set tiny specks of land,
0:01:00 > 0:01:02some the tips of volcanoes,
0:01:02 > 0:01:04some mere rings of coral.
0:01:04 > 0:01:08They're miniature enclosed worlds
0:01:08 > 0:01:12where animals and plants become transformed into new species
0:01:12 > 0:01:13with extraordinary speed.
0:01:40 > 0:01:43If you wanted to pick a really remote desert island cut off from
0:01:43 > 0:01:47the rest of the world, you might well choose this one.
0:01:47 > 0:01:50This is Aldabra in the Indian Ocean.
0:01:50 > 0:01:55The nearest land in that direction is the coast of Africa,
0:01:55 > 0:01:58about 250 miles away.
0:01:58 > 0:02:01Over there, about the same distance, is Madagascar,
0:02:01 > 0:02:05and if you sailed in that direction, you wouldn't hit anything much
0:02:05 > 0:02:09until you got to the coast of Australia 4,000 miles away.
0:02:09 > 0:02:13The island itself is the tip of an extinct submarine volcano
0:02:13 > 0:02:17that rises 15,000 feet from the bottom of the Indian Ocean
0:02:17 > 0:02:21and is capped with coral rock.
0:02:21 > 0:02:25When it finally rose above the surface of the sea
0:02:25 > 0:02:27about 50,000 years ago, it was of course lifeless,
0:02:27 > 0:02:32but now, a mere 50,000 years later, well, just look.
0:02:36 > 0:02:39Frigate birds, thousands of them, circle above one end of the island.
0:02:39 > 0:02:43They've come from all over the Indian Ocean, even from the shores
0:02:43 > 0:02:47of India itself 2,000 miles away, to nest on this particular island
0:02:47 > 0:02:49in the mangroves.
0:02:55 > 0:02:59The white-headed birds among them are immatures,
0:02:59 > 0:03:04and there are two different species of them, one bigger than the other.
0:03:06 > 0:03:09The males inflate their scarlet throat pouches
0:03:09 > 0:03:11to show other cruising birds that the site is taken,
0:03:11 > 0:03:13and to attract the female.
0:03:15 > 0:03:16When she arrives,
0:03:16 > 0:03:20he persuades her to stay with ecstatic shakes of his head.
0:03:36 > 0:03:41Red-footed boobies are here, too. They're also great travellers,
0:03:41 > 0:03:45and their chicks, which are already fledging,
0:03:45 > 0:03:48may well be fishing 3,000 or 4,000 miles away within a year.
0:03:49 > 0:03:53Noddies nest not on Aldabra but on a neighbouring atoll,
0:03:53 > 0:03:57building platforms of seaweed in the Pisonia trees,
0:03:57 > 0:04:00and beneath, on the open coral sand,
0:04:00 > 0:04:03two million sooty terns lay their eggs.
0:04:06 > 0:04:07Their vast numbers are an indication
0:04:07 > 0:04:11of the richness of the surrounding sea.
0:04:11 > 0:04:13Every day, the birds take from it many tons of small fish,
0:04:13 > 0:04:17little squid and other marine creatures.
0:04:24 > 0:04:27The atoll itself provides no food for them.
0:04:27 > 0:04:30All a pair of sooty terns seek from it
0:04:30 > 0:04:34are a few square inches of dry land on which to place their single egg,
0:04:34 > 0:04:39and an absence of cats, rats and all other egg-stealers and chick-eaters
0:04:39 > 0:04:42that so often plague nesting sites on the mainland.
0:04:43 > 0:04:47Such security is specially important to these terns,
0:04:47 > 0:04:51for not only do they lay their eggs
0:04:51 > 0:04:53exposed and unprotected on the ground,
0:04:53 > 0:04:56but their young remain flightless for several weeks after hatching
0:04:56 > 0:04:59and a hungry cat could cause havoc among them.
0:04:59 > 0:05:03So terns find it well worthwhile, for the sake of such security,
0:05:03 > 0:05:06to fly hundreds of miles to this island.
0:05:22 > 0:05:25But the plants that grow on remote islands like Aldabra...
0:05:25 > 0:05:28how do they get here?
0:05:28 > 0:05:31Well, some certainly come by sea.
0:05:31 > 0:05:34In a short walk along this high-water mark,
0:05:34 > 0:05:37I've picked up already three different kinds of seeds.
0:05:37 > 0:05:41Here's the biggest floating seed of them all. This is a coconut.
0:05:45 > 0:05:49There's the familiar nut which contains the white flesh,
0:05:49 > 0:05:53and this husk, from which we sometimes make coconut mats,
0:05:53 > 0:05:55is the flotation device.
0:05:57 > 0:06:00Nuts like this can float in the sea for up to four months.
0:06:00 > 0:06:02This one is already dead...
0:06:04 > 0:06:07..but here is one that's very much alive and still sprouting.
0:06:07 > 0:06:11The green stem springing from the top,
0:06:11 > 0:06:14a white rootlet striking down underneath.
0:06:14 > 0:06:17Under natural conditions, such coconuts establish themselves
0:06:17 > 0:06:19at the head of the beach.
0:06:19 > 0:06:22As they grow taller, they lean out over the sand so that when they're
0:06:22 > 0:06:26full-grown, their nuts will drop within reach of the high tide
0:06:26 > 0:06:30and be washed out to sea to spread to other islands.
0:06:33 > 0:06:36A land-living animal also reached here by sea.
0:06:36 > 0:06:40The time and place to find it is at night among the coconut groves.
0:06:40 > 0:06:44It travelled here as a larva in much the same way as the coconuts,
0:06:44 > 0:06:46floating in the surface waters.
0:06:46 > 0:06:49One or two in a million were washed up on the beach and crawled ashore
0:06:49 > 0:06:53to take up life on land among the coconuts,
0:06:53 > 0:06:55and indeed, feeding on them.
0:06:55 > 0:06:58It's almost the only creature here likely to give you a painful bite,
0:06:58 > 0:07:00so it needs tackling with care.
0:07:02 > 0:07:03It's the coconut crab.
0:07:14 > 0:07:15Its legs are so long
0:07:15 > 0:07:18that it can easily embrace the trunk of a coconut palm,
0:07:18 > 0:07:22and it has no difficulty at all in clambering up to the top.
0:07:22 > 0:07:25There it cuts down the young nuts with its huge pincers,
0:07:25 > 0:07:30and returns to the ground to feed on the soft white coconut flesh.
0:07:30 > 0:07:32Crabs as a group are sea-living creatures
0:07:32 > 0:07:36and breathe in water by means of gills. To breathe in air,
0:07:36 > 0:07:39the coconut crab has developed large pouches within its shell
0:07:39 > 0:07:44that have moist linings and can therefore act as simple lungs.
0:07:44 > 0:07:47But when it breeds, it has to return to the sea.
0:07:47 > 0:07:50There it releases its eggs and sperm into the water at high tide,
0:07:50 > 0:07:54so that its larvae will circulate once more through the sea,
0:07:54 > 0:07:57and may be washed up on some new island.
0:08:06 > 0:08:11One exceptional land animal made the voyage to Aldabra as an adult -
0:08:11 > 0:08:15its most famous inhabitant, the giant tortoise.
0:08:15 > 0:08:18Most tortoises are naturally buoyant.
0:08:18 > 0:08:20If one on the coast of mainland Africa,
0:08:20 > 0:08:23grazing perhaps among the mangroves, were swept out to sea,
0:08:23 > 0:08:26it might well survive long enough to be carried by currents
0:08:26 > 0:08:30to the islands of the Indian Ocean, and later to spread among them.
0:08:30 > 0:08:32and that, almost certainly,
0:08:32 > 0:08:36is how the ancestors of the Aldabran giant tortoise reached here.
0:08:38 > 0:08:42It's not however a very hospitable place for animals like tortoises
0:08:42 > 0:08:45that feed on land-living plants.
0:08:45 > 0:08:48The coral rock which forms the substance of the island
0:08:48 > 0:08:53erodes into a honeycomb of wickedly sharp blades and spikes.
0:08:54 > 0:08:56Any creature moving over it
0:08:56 > 0:09:00has to step with care if it's not to cut itself badly.
0:09:12 > 0:09:14Here and there,
0:09:14 > 0:09:18the rock forms deep pits into which tortoises sometimes tumble.
0:09:18 > 0:09:22When that happens, there is no escape, and the trapped animals,
0:09:22 > 0:09:26even if they survive the fall, die from starvation
0:09:28 > 0:09:31Quite apart from such traps,
0:09:31 > 0:09:34the island is a harsh, taxing place in which to live.
0:09:34 > 0:09:39The tropical sun, beating down on the animals, threatens to bake them
0:09:39 > 0:09:43alive inside their shells, and the remains of casualties are common.
0:09:47 > 0:09:49So as the day heats up,
0:09:49 > 0:09:54the tortoises head determinedly for the few trees that can provide shade.
0:09:56 > 0:10:03Here and there on some beaches grow low, windswept Guettarda trees.
0:10:03 > 0:10:06By noon, the ground beneath their branches is packed with
0:10:06 > 0:10:10refugees from the sun, waiting for the temperature to fall a little
0:10:10 > 0:10:13so that they can return to search for a few edible leaves.
0:10:17 > 0:10:19Birds, too, can overheat.
0:10:20 > 0:10:24The frigates swoop over the one almost permanent lagoon of rainwater
0:10:24 > 0:10:28on the island, snatching sips from its surface.
0:10:55 > 0:10:58Tortoises, too, must have fresh water.
0:10:58 > 0:11:00Although they don't drink every day,
0:11:00 > 0:11:03they must do every week or so if they're to survive.
0:11:20 > 0:11:24Water can also cool an overheated body.
0:11:29 > 0:11:30As the dry season progresses,
0:11:30 > 0:11:35the water evaporates and the pools get smaller and more crowded.
0:12:09 > 0:12:14Many that came here for relief are near the end of their strength.
0:12:14 > 0:12:17Some are unable to drag themselves out of the mud,
0:12:17 > 0:12:19and so die of starvation.
0:12:31 > 0:12:34And yet, in spite of all these hardships,
0:12:34 > 0:12:37the tortoises breed and proliferate.
0:12:37 > 0:12:41There are some 150,000 of them on the atoll.
0:12:41 > 0:12:45Their staple food is vegetation and they crop the grass right down
0:12:45 > 0:12:46to the rootstock.
0:12:51 > 0:12:55But as island animals everywhere tend to do, they've broadened their
0:12:55 > 0:13:00taste in food to include almost anything that is remotely edible,
0:13:00 > 0:13:03including the carcasses of their dead companions.
0:13:13 > 0:13:17Flesh is too nutritious to be allowed to rot and go to waste
0:13:17 > 0:13:20in this land where there is so little to eat.
0:13:31 > 0:13:3550,000 years, which is the time, apparently, that Aldabra has been
0:13:35 > 0:13:39above the sea, is not a very long time in terms of evolution.
0:13:39 > 0:13:43Nonetheless, 50,000 years of isolation on the island
0:13:43 > 0:13:48has brought changes to many of the plants and animals that live here.
0:13:48 > 0:13:50They've begun to take on their own character,
0:13:50 > 0:13:54so that now they are slightly different both from the ancestors
0:13:54 > 0:13:56which originally colonised the island
0:13:56 > 0:13:59and from their nearest relations anywhere else in the world.
0:14:01 > 0:14:05For example, this close-cropped withered turf around me
0:14:05 > 0:14:08contains about 20 different species of plants.
0:14:08 > 0:14:13All have been relentlessly cropped by giant tortoises like that.
0:14:13 > 0:14:18And look, for example, at this little sedge.
0:14:20 > 0:14:23Most sedges bear their flowers at the top of stems that rise quite
0:14:23 > 0:14:25high above the rest of the leaves.
0:14:25 > 0:14:30Flowers sticking up like this would not survive long on Aldabra.
0:14:30 > 0:14:31The tortoises would eat them.
0:14:31 > 0:14:36And now, these Aldabran sedges bear their flowers and develop their seeds
0:14:36 > 0:14:39very close to the rootstock where the jaws of the hungry tortoises
0:14:39 > 0:14:41can't reach them.
0:14:43 > 0:14:46The changes that take place in an island species are not always
0:14:46 > 0:14:48directly useful like that.
0:14:48 > 0:14:51Another of Aldabra's plants has changed in a way
0:14:51 > 0:14:55that seems to have no practical significance at all.
0:14:55 > 0:14:58This is a kind of lily called Lomatophyllum
0:14:58 > 0:15:01and it's just slightly different in colour from any other Lomatophyllum
0:15:01 > 0:15:04growing elsewhere, but that's all.
0:15:04 > 0:15:06The difference of course, is very trivial.
0:15:09 > 0:15:12But some island plants are spectacularly different
0:15:12 > 0:15:14from their nearest relatives.
0:15:14 > 0:15:18Very, very rarely, extraordinary double nuts like this
0:15:18 > 0:15:23are washed up on the shores of the coral islands of the Indian Ocean.
0:15:23 > 0:15:26For centuries, nobody had any idea where they came from.
0:15:26 > 0:15:30Some people said they were produced by fantastic palm trees
0:15:30 > 0:15:35that grew under the surface of the sea, so they were called coco-de-mer.
0:15:35 > 0:15:39People believed that their kernels could be made into absolutely
0:15:39 > 0:15:43irresistible love potions and that their shells, when turned into a cup,
0:15:43 > 0:15:48would render even the most powerful poison absolutely harmless.
0:15:48 > 0:15:52And so a single nut like this was literally worth a king's ransom.
0:15:52 > 0:15:54It wasn't until the 18th century
0:15:54 > 0:15:58that people discovered that the palms that produced these nuts grew in
0:15:58 > 0:16:02just one tiny group of islands in the Seychelles,
0:16:02 > 0:16:05some 700 miles from Aldabra.
0:16:06 > 0:16:09The largest surviving group of these trees
0:16:09 > 0:16:12stands on the little island of Praslin.
0:16:44 > 0:16:47There are male and female trees.
0:16:47 > 0:16:52The males produce small yellow flowers on long spikes,
0:16:52 > 0:16:56and on them lives a little gecko, feeding on their nectar and pollen.
0:16:57 > 0:17:01Once again, it's an island original, slightly different in colour
0:17:01 > 0:17:04from others in its kind in neighbouring islands.
0:17:05 > 0:17:09The female flowers start as small reddish buds, no bigger than
0:17:09 > 0:17:12a man's fist, but they will eventually develop
0:17:12 > 0:17:15into the biggest seed produced by any plant.
0:17:22 > 0:17:26It takes seven years for the nuts to develop,
0:17:26 > 0:17:31and when they are mature, they are so large and so heavy
0:17:31 > 0:17:34that almost the only way of opening them is with a saw.
0:17:34 > 0:17:39Inside, you can see how very different they are from coconuts.
0:17:39 > 0:17:42Not only do they have two lobes to them,
0:17:42 > 0:17:47but the nut itself is full solid with flesh.
0:17:47 > 0:17:51Flesh that is so heavy that these mature nuts won't float in sea water.
0:17:51 > 0:17:53Indeed, sea water kills them.
0:17:54 > 0:17:57And that means two things.
0:17:57 > 0:18:00First of all, that these palms have never been able
0:18:00 > 0:18:03to spread naturally to any other islands,
0:18:03 > 0:18:07and secondly, that they must have actually evolved here.
0:18:08 > 0:18:11Isolation changes not only plants but animals.
0:18:11 > 0:18:15On Aldabra, wandering among the tortoises are sacred ibis
0:18:15 > 0:18:18with light blue eyes.
0:18:18 > 0:18:20Others elsewhere have dark eyes.
0:18:20 > 0:18:23The Aldabran ibis are residents, breeding among themselves and
0:18:23 > 0:18:26feeding on small shore creatures.
0:18:26 > 0:18:28Land crabs are far too big to be eaten,
0:18:28 > 0:18:32but they have to be pecked to clear them out of the way.
0:18:36 > 0:18:40Several species of Aldabran birds have developed slight variations
0:18:40 > 0:18:41that make them unique.
0:18:41 > 0:18:45The kestrel here is slightly smaller than the Madagascar species,
0:18:45 > 0:18:47but otherwise the same.
0:18:47 > 0:18:49The Aldabran sunbird, however,
0:18:49 > 0:18:52is a little darker than its African relations.
0:19:01 > 0:19:05But perhaps the most dramatic and certainly the most endearing quality
0:19:05 > 0:19:10brought to some of the birds of Aldabra by isolation is this.
0:19:12 > 0:19:16Not only extreme tameness, but flightlessness.
0:19:16 > 0:19:18This is the Aldabran rail.
0:19:18 > 0:19:21Flying takes a lot of energy.
0:19:21 > 0:19:25It's of obvious value when escaping ground-living enemies,
0:19:25 > 0:19:29but there are no such enemies on Aldabra or many other remote islands.
0:19:29 > 0:19:34So some birds that reach such islands by air have now given up flying.
0:19:34 > 0:19:36Their wing muscles have dwindled
0:19:36 > 0:19:39and they can't fly even if they wanted to.
0:19:39 > 0:19:41The Aldabran rail is only one example.
0:19:42 > 0:19:47A kind of pigeon once lived on another island in the Indian Ocean -
0:19:47 > 0:19:48Mauritius.
0:19:48 > 0:19:52It, too, became flightless and grew as big as a turkey.
0:19:52 > 0:19:56It was so tame that European sailors were able to kill it with clubs
0:19:56 > 0:19:58without any difficulty.
0:19:58 > 0:20:02They called it the dodo, and in less than 200 years after finding it,
0:20:02 > 0:20:04they'd exterminated it.
0:20:05 > 0:20:08Grazing alongside the dodo in Mauritius,
0:20:08 > 0:20:11and living in other islands in the Indian Ocean as well,
0:20:11 > 0:20:13were giant tortoises.
0:20:13 > 0:20:15They, too, were taken for food by seamen
0:20:15 > 0:20:18and they too were eventually exterminated.
0:20:18 > 0:20:22But Aldabra is so remote that few ships come anywhere near it,
0:20:22 > 0:20:25and here alone, the tortoises have survived.
0:20:28 > 0:20:32It seems likely that the African ancestors of these creatures
0:20:32 > 0:20:35were of a normal size, and that these tortoises became giants
0:20:35 > 0:20:38as a consequence of living on islands.
0:20:41 > 0:20:45Isolation may have had another effect on the tortoises as well.
0:20:45 > 0:20:47When African tortoises are threatened,
0:20:47 > 0:20:51they behave in the same way as this baby Aldabran tortoise does.
0:20:51 > 0:20:54that is to say, they first pull in their head,
0:20:54 > 0:20:58and then they pull after it their heavily armoured front legs
0:20:58 > 0:21:00so that nothing sticks out
0:21:00 > 0:21:04and they're comparatively safe from their enemies.
0:21:04 > 0:21:08But when the Aldabran tortoise grows up, its proportions change,
0:21:08 > 0:21:12as this one's have done. This one is now so big
0:21:12 > 0:21:16that these huge legs won't fit into this space, here,
0:21:16 > 0:21:19so that whatever it does, something sticks out.
0:21:19 > 0:21:24It's a fair bet that if there was let's say, a hyena on the island,
0:21:24 > 0:21:27it would make a meal of the giant tortoise.
0:21:27 > 0:21:30But there isn't on Aldabra, so this creature's safe
0:21:32 > 0:21:36Just why the island tortoises should have grown so huge,
0:21:36 > 0:21:40and another species has done the same in the Galapagos islands,
0:21:40 > 0:21:41is by no means clear.
0:21:42 > 0:21:45It may be that a large animal with big reserves of fat
0:21:45 > 0:21:50is better able to survive really bad seasons when there's little to eat.
0:21:50 > 0:21:53It may even be that with no predators on the island,
0:21:53 > 0:21:56these long-lived creatures just go on growing,
0:21:56 > 0:21:59but it is not a phenomenon that is restricted to tortoises.
0:21:59 > 0:22:03On an island 3,000 miles away from Aldabra,
0:22:03 > 0:22:05there is another giant reptile.
0:22:08 > 0:22:11Komodo is a small island in Indonesia.
0:22:11 > 0:22:13From here, back in the 1920s,
0:22:13 > 0:22:18came stories of a huge lizard that became known as the Komodo dragon,
0:22:18 > 0:22:21and here the dragons still live.
0:22:45 > 0:22:46It's not difficult to find them.
0:22:46 > 0:22:48All you need is the carcass of a goat,
0:22:48 > 0:22:51preferably somewhat decayed and smelly,
0:22:51 > 0:22:53and the scent will attract them from miles around.
0:23:24 > 0:23:30It used to be thought that these very big ones were entirely scavengers,
0:23:30 > 0:23:33relying on what carrion they could find,
0:23:33 > 0:23:38but now we know that actually they are active killers.
0:23:38 > 0:23:48They attack and kill goats, young buffalo, and even on occasion, man.
0:23:48 > 0:23:52The reason that I can stand here with relative safety
0:23:52 > 0:23:57is that their eyesight is not very good, they are almost deaf,
0:23:57 > 0:24:00and they rely on their senses,
0:24:00 > 0:24:05primarily on that big yellow tongue which flicks out and tastes the air.
0:24:08 > 0:24:12So with any luck, the smell of these dead goats is more powerful
0:24:12 > 0:24:15than mine, so they will take no notice of me.
0:24:16 > 0:24:21They are, in fact, the kings of their island. They are the top predator.
0:24:21 > 0:24:26There is nothing here which preys upon them and is bigger,
0:24:26 > 0:24:29and nothing with which they have to share their food.
0:24:30 > 0:24:32So, from that point of view,
0:24:32 > 0:24:36there is no reason why they shouldn't grow big.
0:24:36 > 0:24:40And the fact is that there is a positive advantage in growing big,
0:24:40 > 0:24:44because, as you can see, the big ones are getting
0:24:44 > 0:24:46the bigger share of the food.
0:24:47 > 0:24:49Not only that,
0:24:49 > 0:24:54but we now know that these big ones actually eat small ones.
0:24:54 > 0:25:00So that perhaps is a reason why, in the isolation of their island,
0:25:00 > 0:25:03these kings of Komodo have grown so huge.
0:25:05 > 0:25:08And they are indeed immense.
0:25:08 > 0:25:11They're related to the water monitors of Asia and Africa
0:25:11 > 0:25:14and the goannas of Australia, but they are much more massive,
0:25:14 > 0:25:18for whereas some two-thirds of the length of these other monitors
0:25:18 > 0:25:20is taken up by a long thin tail,
0:25:20 > 0:25:24the dragon's tail is only about half its length.
0:25:24 > 0:25:28Big ones like this can weigh up to 100 pounds
0:25:28 > 0:25:30and grow to over nine feet long.
0:25:37 > 0:25:39Komodo is not, like Aldabra,
0:25:39 > 0:25:43a coral atoll growing on the drowned tip of a submarine volcano, but the
0:25:43 > 0:25:47eroded remains of one that stood many thousands of feet above sea level.
0:25:49 > 0:25:53Volcanoes, indeed, have built many of the most isolated islands.
0:25:53 > 0:25:57The Hawaiian islands, lying in the eastern Pacific, are all volcanic,
0:25:57 > 0:26:00and the biggest and newest of them is still erupting.
0:26:29 > 0:26:31Torrents of basaltic lava
0:26:31 > 0:26:34erupting from vents 10,000 feet up on the mountain
0:26:34 > 0:26:38sometimes flow for many miles down the volcano's flanks.
0:26:56 > 0:26:58When, eventually, they cool and solidify,
0:26:58 > 0:27:02they become vast slopes of black naked rock.
0:27:05 > 0:27:10Such areas as this may remain virtually sterile for decades.
0:27:13 > 0:27:17Some vents produce vast quantities of granular ash which builds up
0:27:17 > 0:27:20around them into cones.
0:27:20 > 0:27:23Plants have a better chance of getting root on such material,
0:27:23 > 0:27:27and within a century or so, the ash slopes may be covered with green.
0:27:29 > 0:27:32These high islands collect moisture-laden clouds,
0:27:32 > 0:27:36and on the windward side, rain falls very heavily indeed.
0:27:37 > 0:27:39Streams flowing down the mountainside
0:27:39 > 0:27:44cut through the layers of loosely compacted ash, eroding deep valleys.
0:27:44 > 0:27:47So, unlike a coral atoll,
0:27:47 > 0:27:51which is a plain platform of coral, sand and rock only a few feet high,
0:27:51 > 0:27:53these immense volcanic islands of Hawaii
0:27:53 > 0:27:57offered their colonists a great variety of habitats
0:27:57 > 0:28:00from high cold slopes of ash on the summits
0:28:00 > 0:28:05to well-watered valleys, hot, lush and humid, near sea level,
0:28:05 > 0:28:09from new, naked basalt to long-established forest growing
0:28:09 > 0:28:10on ancient lava flows.
0:28:10 > 0:28:16To exploit them, the animal colonists changed not into just one new form,
0:28:16 > 0:28:18but into a multitude.
0:28:20 > 0:28:23This bird, the palila, is one of a large family
0:28:23 > 0:28:27of closely related Hawaiian birds the honeycreepers.
0:28:27 > 0:28:29Their ancestors were probably finch-like birds
0:28:29 > 0:28:34that were swept here, perhaps by a storm, many thousands of years ago.
0:28:34 > 0:28:38Once here, they developed into over 30 different species,
0:28:38 > 0:28:40each with its own diet and habitat.
0:28:40 > 0:28:43The palila lives largely on seeds
0:28:43 > 0:28:47and has the kind of short, powerful beak needed to open and crack them.
0:28:52 > 0:28:56The 'amakihi, while its body is so similar to the palila that there's
0:28:56 > 0:28:58no doubt that the two are closely related,
0:28:58 > 0:29:02has a slender beak, suited to picking up small insects
0:29:02 > 0:29:05and sipping nectar from shallow flowers.
0:29:05 > 0:29:06Some species have also developed
0:29:06 > 0:29:09striking feather colours and adornments.
0:29:09 > 0:29:12These enable the male and female to identify one another
0:29:12 > 0:29:15so they don't interbreed with their near cousins,
0:29:15 > 0:29:17and the species becomes increasingly distinct.
0:29:19 > 0:29:21So the 'apapane not only has a longer beak
0:29:21 > 0:29:24to suit its almost exclusive diet of nectar,
0:29:24 > 0:29:26but a conspicuous red head.
0:29:28 > 0:29:32The 'akohekohe lives on a mixed diet of insects and nectar,
0:29:32 > 0:29:35and has developed a little crest of white feathers
0:29:35 > 0:29:36at the base of its beak.
0:29:40 > 0:29:44The 'i'iwi is scarlet and has a particularly long curved bill
0:29:44 > 0:29:49that allows it to probe deep into trumpet-shaped flowers
0:29:49 > 0:29:51such as giant lobelias and bananas.
0:30:02 > 0:30:05And perhaps most engaging of all, the akiapolaau,
0:30:05 > 0:30:09with a splendid dual-purpose beak,
0:30:09 > 0:30:13the lower mandible pick-like to chip away bark to find insects,
0:30:13 > 0:30:14and an upper mandible
0:30:14 > 0:30:18elongated into a probe with which to winkle them out.
0:30:22 > 0:30:25It's located a beetle larva burrowing away within the bark.
0:30:25 > 0:30:29Look how dexterously it uses the two halves of its beak
0:30:29 > 0:30:31for these different purposes.
0:30:44 > 0:30:48The situation amongst Hawaii's insects is even more extreme
0:30:48 > 0:30:49than it is among its birds.
0:30:49 > 0:30:52There is a kind of fly called Drosophila.
0:30:52 > 0:30:54It's found in many parts of the world.
0:30:54 > 0:30:58In North America, for example, there are about 200 species,
0:30:58 > 0:31:03but here in these relatively tiny islands of Hawaii,
0:31:03 > 0:31:05there are at least 800.
0:31:05 > 0:31:08It seems that soon after the islands' formation,
0:31:08 > 0:31:13one or at most two species of Drosophila reached the islands,
0:31:13 > 0:31:17and they found the same situation as the honeycreepers found,
0:31:17 > 0:31:18a lot of vacant niches.
0:31:18 > 0:31:23And so they evolved to fill them, and they are now Drosophila,
0:31:23 > 0:31:29the larvae of which feed on fruit or rotting leaves or fungi,
0:31:29 > 0:31:32or bark or even spiders' eggs.
0:31:32 > 0:31:35But now the situation become more complex because in Hawaii,
0:31:35 > 0:31:40there are lava flows like this, and such lava flows often isolate
0:31:40 > 0:31:44patches of ancient forest like that over there,
0:31:44 > 0:31:49and in one small patch of forest, there may well be one particular
0:31:49 > 0:31:53species of Drosophila that occurs nowhere else.
0:32:16 > 0:32:19And there are some just there.
0:32:28 > 0:32:31These particular ones belong to a group which for some reason
0:32:31 > 0:32:35have evolved, in their isolation, an extraordinary courtship behaviour,
0:32:35 > 0:32:39just as some honeycreepers have evolved bright colours.
0:32:39 > 0:32:42It's an insect equivalent of the arena display of antelope.
0:32:42 > 0:32:45The rival males maintain tiny territories
0:32:45 > 0:32:48and display and battle with one another.
0:32:48 > 0:32:52Instead of antlers, they've developed heads shaped like mallets.
0:33:01 > 0:33:05In another species, the male courts the female by hoisting his abdomen
0:33:05 > 0:33:08over his back and showering her with an aphrodisiac perfume.
0:33:11 > 0:33:15Isolation has also affected the wings of Hawaiian insects.
0:33:15 > 0:33:17Flying on an island is dangerous.
0:33:17 > 0:33:19It risks being blown out to sea...
0:33:21 > 0:33:25..and this extraordinary bug never takes to the air.
0:33:25 > 0:33:29Its wings are tiny, and used only for flirting in courtship.
0:33:32 > 0:33:34This lacewing can't even use them for that.
0:33:34 > 0:33:38Its wings have become fused together to form a shell.
0:33:38 > 0:33:42The Hawaiian cranefly has lost its wings completely.
0:33:42 > 0:33:45This cranefly's taste for fruit is typical of its family,
0:33:45 > 0:33:49but other insects have changed their feeding habits.
0:33:49 > 0:33:53This flightless bug has adopted the hunting techniques of the mantis
0:33:53 > 0:33:55which never naturally reached the island.
0:33:58 > 0:34:00And this fly is going to get a shock.
0:34:03 > 0:34:06The twig caterpillar doesn't, like most twig caterpillars elsewhere,
0:34:06 > 0:34:09feed on leaves, but has become a carnivore.
0:34:20 > 0:34:24It detected the fly with tiny hairs on its back end.
0:34:24 > 0:34:27They trigger the caterpillar to arch backwards and pounce
0:34:27 > 0:34:28on whatever touched it.
0:34:33 > 0:34:34So isolation, by restricting
0:34:34 > 0:34:37the kinds of creature that reached Hawaii,
0:34:37 > 0:34:41allows those that did great freedom to develop into all kinds
0:34:41 > 0:34:43of different and unexpected forms.
0:34:46 > 0:34:49Human beings, the Polynesians,
0:34:49 > 0:34:52reached Hawaii several thousand years ago.
0:34:52 > 0:34:55When Europeans arrived, they found to their surprise
0:34:55 > 0:34:59an unknown people with an elaborate and splendid culture.
0:34:59 > 0:35:01The Hawaiians were superb seamen.
0:35:01 > 0:35:05They not only paddled dugout canoes, but sailed immense ocean-going
0:35:05 > 0:35:09double canoes that could carry several hundred passengers,
0:35:09 > 0:35:13and that tradition survives still in many parts of the Pacific.
0:35:24 > 0:35:28The last of the really big canoes must have disappeared about
0:35:28 > 0:35:33100 years ago, but still, in the remoter parts of the Pacific,
0:35:33 > 0:35:37people remembered the techniques that were used to sail them,
0:35:37 > 0:35:41and still practise the skills necessary to build them.
0:35:41 > 0:35:45This particular canoe, which is very big for modern times,
0:35:45 > 0:35:47was built on the tiny island of Ribono in Kiribati
0:35:47 > 0:35:51the islands that used to be called the Gilberts.
0:35:51 > 0:35:55It is only about 50 feet long, enormous for today,
0:35:55 > 0:35:57but only half the size of the old canoes,
0:35:57 > 0:35:59and still the people are perfectly
0:35:59 > 0:36:03prepared to sail on journeys of up to 1,000 miles in it.
0:36:03 > 0:36:08And the techniques for building it are exactly those that were used
0:36:08 > 0:36:09for the old canoes.
0:36:09 > 0:36:12The lashings, for instance.
0:36:12 > 0:36:15They are made from the fibres of coconut husks.
0:36:15 > 0:36:18Clumps are teased out, rolled and twisted
0:36:18 > 0:36:22so that each fibre binds with its neighbours. It is a repetitious job,
0:36:22 > 0:36:25but a very skilled one if the string is going to be strong,
0:36:25 > 0:36:28and it is taken on by the women and the old people.
0:36:28 > 0:36:32Many hundreds of yards will be needed to build a big canoe.
0:36:39 > 0:36:42It's used not only for lashing one spar to another
0:36:42 > 0:36:44but for sewing together the planks
0:36:44 > 0:36:47that form the sides of the big canoes.
0:37:12 > 0:37:16The Pandanus tree produces strap-like leaves, which,
0:37:16 > 0:37:20when dried and split, provide flat ribbons that are woven into
0:37:20 > 0:37:23strong and durable mats to serve as sails.
0:37:32 > 0:37:35So if you have the necessary knowledge and skill,
0:37:35 > 0:37:38even a small atoll can provide
0:37:38 > 0:37:42all the materials necessary to build an ocean-going canoe.
0:37:42 > 0:37:46In such craft, the Polynesians travelled right across the Pacific.
0:37:46 > 0:37:50For a long time, Europeans, so proud of their own navigating skills,
0:37:50 > 0:37:53maintained that the Polynesian voyages were accidental,
0:37:53 > 0:37:56made when fishing canoes were blown off course.
0:37:56 > 0:37:59But the huge canoes carried women and children,
0:37:59 > 0:38:02and were loaded with plants and animals,
0:38:02 > 0:38:05clearly with every intention of founding new colonies.
0:38:07 > 0:38:11The Polynesian navigators had and have the most astonishing
0:38:11 > 0:38:14powers of observation by which they find their way.
0:38:14 > 0:38:17A particular kind of bird during one season of the year
0:38:17 > 0:38:20will always be travelling in a certain direction.
0:38:20 > 0:38:22Some birds are ocean-goers,
0:38:22 > 0:38:26others seldom travel far from their nesting grounds,
0:38:26 > 0:38:30so spotting one can indicate that there's land close by,
0:38:30 > 0:38:32and following it may take you there.
0:38:35 > 0:38:37Distant islands can be detected
0:38:37 > 0:38:41by their effect on the ripples on the surface of the sea.
0:38:42 > 0:38:45Tall islands trail clouds of characteristic shape
0:38:45 > 0:38:47like smoke from a chimney blown by the wind,
0:38:47 > 0:38:51and since they are so high in the sky, they can be recognised
0:38:51 > 0:38:54and identified long before the island itself is visible.
0:38:55 > 0:38:59Using such techniques as well as observing the sun and the stars,
0:38:59 > 0:39:00the pattern of the winds,
0:39:00 > 0:39:04and feeling through the rudder the movements of swells and currents,
0:39:04 > 0:39:07the Polynesians colonised island after island.
0:39:07 > 0:39:10Their original home was in the western Pacific.
0:39:10 > 0:39:13They reached the Tahitian islands, right in the centre of the ocean,
0:39:13 > 0:39:15over 2,000 years ago.
0:39:18 > 0:39:19They sailed so far eastward
0:39:19 > 0:39:22that eventually they reached Easter Island,
0:39:22 > 0:39:25three-quarters of the way to the coast of South America.
0:39:26 > 0:39:30Those that settled here seem to have been more isolated than most,
0:39:30 > 0:39:32and, like so many other islanders,
0:39:32 > 0:39:35they developed their own individual culture.
0:39:35 > 0:39:39They carved the rocks of their headlands into strange shapes.
0:39:39 > 0:39:41On the flanks of the great volcano that built their island,
0:39:41 > 0:39:46they set up huge images whose enigmatic faces have haunted
0:39:46 > 0:39:47the European imagination
0:39:47 > 0:39:52ever since they were discovered by westerners two centuries ago.
0:40:04 > 0:40:06The heyday of the Easter Island culture
0:40:06 > 0:40:10seems to have been passed long before Europeans arrived,
0:40:10 > 0:40:15for many of the statues were already overturned and some lay half-finished
0:40:15 > 0:40:18and abandoned where they had been carved in the quarries.
0:40:29 > 0:40:33The scale of these Polynesian voyages is difficult to imagine.
0:40:33 > 0:40:35From their headquarters in Samoa
0:40:35 > 0:40:39to their most northerly colony in Hawaii,
0:40:39 > 0:40:44which they reached by way of the Marquesas, was some 5,000 miles.
0:40:44 > 0:40:48The journey to Easter Island, about 3,300 miles.
0:40:48 > 0:40:51But the most extraordinary voyage of all is that which
0:40:51 > 0:40:56took them across 4,000 miles of open ocean, south to New Zealand.
0:40:57 > 0:41:01The group that landed here, ancestors of the Maori,
0:41:01 > 0:41:04arrived about 1,500 years ago.
0:41:05 > 0:41:08The land they discovered must have been a great surprise to them,
0:41:08 > 0:41:11for it was very different from any of the tropical islands
0:41:11 > 0:41:13from which they had come.
0:41:13 > 0:41:16For much of the year, it was bitterly cold.
0:41:17 > 0:41:21In the South Island stood great mountain ranges covered with snow
0:41:21 > 0:41:24and ice that the Maori can never have seen before.
0:41:26 > 0:41:31Not only that, but the forests were far, far richer in animals and plants
0:41:31 > 0:41:34than any island they had yet discovered.
0:41:34 > 0:41:38That was because these islands had a very different origin and history.
0:41:39 > 0:41:43They were neither flat coral atolls nor were they the tips of volcanoes
0:41:43 > 0:41:47that had risen above the surface of the Pacific in comparatively
0:41:47 > 0:41:49recent geological time.
0:41:49 > 0:41:52These islands of New Zealand were ancient lands.
0:41:52 > 0:41:54Fragments of a great supercontinent
0:41:54 > 0:41:59of which Australia, Antarctica and South America had also been a part.
0:41:59 > 0:42:04And in consequence, they had on them many more different kinds of animals
0:42:04 > 0:42:06than those other more recent islands.
0:42:06 > 0:42:09They had animals for example, like this.
0:42:10 > 0:42:13This is the tuatara.
0:42:13 > 0:42:19It's a reptile, it's nocturnal and solitary, and it's a flesh-eater.
0:42:19 > 0:42:25It feeds on insects, earthworms and even young nestling birds.
0:42:25 > 0:42:27It might look like a lizard,
0:42:27 > 0:42:30but in fact it's a much more ancient creature than that,
0:42:30 > 0:42:33more closely related to the early dinosaurs
0:42:33 > 0:42:36than it is to the modern family of lizards.
0:42:36 > 0:42:38Once, creatures like it must have swarmed
0:42:38 > 0:42:40over that great supercontinent,
0:42:40 > 0:42:44but New Zealand split away from the supercontinent
0:42:44 > 0:42:47before the great expansion of the early mammals which ultimately led
0:42:47 > 0:42:51to the extinction of most of the early reptiles.
0:42:51 > 0:42:56Only in New Zealand did the tuatara remain safe.
0:42:56 > 0:43:01And New Zealand also has been a sanctuary for another early creature.
0:43:03 > 0:43:07The kiwi. It's a bird, but what an odd one.
0:43:07 > 0:43:11It has no visible wings and no tail and lives in a burrow.
0:43:15 > 0:43:20There, it produces a single and enormous egg.
0:43:27 > 0:43:29Flightless, living in burrows,
0:43:29 > 0:43:33with feathers so long and loose they look like a kind of shaggy fur,
0:43:33 > 0:43:37and running quietly across the forest floor at night in search of food,
0:43:37 > 0:43:42this odd animal could be considered a kind of bird equivalent of a mammal.
0:43:42 > 0:43:46And indeed, the kiwi does play that role in these islands
0:43:46 > 0:43:50where originally there were no land mammals of any kind.
0:43:59 > 0:44:00It has, however,
0:44:00 > 0:44:04retained that characteristic possession of the bird, a beak...
0:44:05 > 0:44:07..and it uses it to collect worms,
0:44:07 > 0:44:12plunging it deep into the earth to smell for them as a mammal does.
0:44:15 > 0:44:17The ancestors of the kiwi
0:44:17 > 0:44:20were flightless before New Zealand was isolated,
0:44:20 > 0:44:22for the kiwi is a ratite.
0:44:23 > 0:44:26Other members of that family of ancient flightless birds
0:44:26 > 0:44:30still survive on other fragments of the great supercontinent.
0:44:30 > 0:44:32There's the ostrich in Africa,
0:44:32 > 0:44:35the rhea in South America and the emu in Australia.
0:44:35 > 0:44:38Of course, all those are very much bigger than the kiwi,
0:44:38 > 0:44:42but the kiwi once had a cousin living here in New Zealand
0:44:42 > 0:44:44that was bigger than the lot of them.
0:44:44 > 0:44:49In fact it was probably the tallest bird that has ever existed, the moa.
0:44:51 > 0:44:54Its bones have been found in great numbers here in New Zealand.
0:44:54 > 0:45:00And often in between the ribs have been found piles of polished pebbles.
0:45:00 > 0:45:03They were the stones from the gizzard
0:45:03 > 0:45:06with which the moa ground up its food,
0:45:06 > 0:45:11and from the vegetable remains, among those, we know that it ate fruit,
0:45:11 > 0:45:13twigs and the leaves of trees.
0:45:15 > 0:45:20There were a dozen or so different species of moa of varying sizes.
0:45:21 > 0:45:24This particular one was the biggest of all.
0:45:24 > 0:45:28It was not the heaviest bird that has ever lived, its relative,
0:45:28 > 0:45:31the extinct elephant bird that once lived in Madagascar was that,
0:45:31 > 0:45:36but its weight nonetheless was substantial, about 520 pounds,
0:45:36 > 0:45:42and it was the tallest of all birds, standing over 13 feet high.
0:45:42 > 0:45:45In fact, it was the bird equivalent of a giraffe.
0:45:48 > 0:45:53This is the mummified head and neck of one of the smaller species of moa,
0:45:53 > 0:45:58and it suggests, because many necks have been found attached to heads,
0:45:58 > 0:46:01that the Maori had so much moa meat
0:46:01 > 0:46:06that they could afford to throw away sections like this.
0:46:06 > 0:46:10The Maori not only reduced the number of moa by hunting,
0:46:10 > 0:46:14they also burnt down the forests on which the moas depended.
0:46:14 > 0:46:19And so, by the time the Europeans arrived here in the 18th century,
0:46:19 > 0:46:23the last of the moas had been extinct for some 200 years.
0:46:26 > 0:46:29But in the millions of years that have passed since New Zealand was
0:46:29 > 0:46:34isolated as islands, many more modern creatures have arrived here.
0:46:34 > 0:46:37And they've got here, as they've managed to get to islands
0:46:37 > 0:46:39all over the world, by flying.
0:46:41 > 0:46:43Some have changed only a little since they arrived.
0:46:43 > 0:46:47The kereru is still quite clearly a kind of pigeon
0:46:54 > 0:46:58And this, the kea, is still recognisably a parrot.
0:46:59 > 0:47:01Its ancestors came, doubtless,
0:47:01 > 0:47:05from that great parrot homeland, Australia, 1,000 miles away.
0:47:05 > 0:47:09Since it's been here, it's probably changed its habits a good deal,
0:47:09 > 0:47:12for it's taken up life in the cold, high mountains
0:47:12 > 0:47:16where it feeds on berries and roots, buds and insects.
0:47:25 > 0:47:30It has also, with that adaptability of diet characteristic of islanders,
0:47:30 > 0:47:32become a general scavenger,
0:47:32 > 0:47:36and will even feed on carrion like a crow or small vulture.
0:47:37 > 0:47:42One parrot, here, however, has been changed extremely by island life.
0:47:43 > 0:47:45The kakapo.
0:47:45 > 0:47:48There are no ground-living leaf-eating mammals on the island,
0:47:48 > 0:47:51so this has become a kind of parrot-equivalent of a rabbit.
0:47:55 > 0:48:01It's extremely nervous, nocturnal, and it lives on vegetation,
0:48:01 > 0:48:07but it shows the two characteristics of island-living creatures.
0:48:07 > 0:48:10It has lost its powers of flight,
0:48:10 > 0:48:16so its only defence is to freeze motionless as it's doing now.
0:48:17 > 0:48:21And secondly, it's a giant.
0:48:21 > 0:48:25It's the biggest of all the parrots by weight.
0:48:26 > 0:48:30A big one can weigh over three kilos.
0:48:32 > 0:48:35It also shows only too vividly
0:48:35 > 0:48:39a third characteristic of island-living forms -
0:48:39 > 0:48:43their extreme vulnerability.
0:48:43 > 0:48:47When their islands are invaded by outsiders,
0:48:47 > 0:48:50they often have no defence.
0:48:50 > 0:48:51The kakapo's troubles started
0:48:51 > 0:48:55when the Polynesians first came to New Zealand.
0:48:55 > 0:49:00They brought a kind of rat which may have preyed upon the nestling kakapo,
0:49:00 > 0:49:03and the Polynesians themselves hunted it.
0:49:04 > 0:49:09The real catastrophe came when Europeans arrived,
0:49:09 > 0:49:13because they brought with them those two merciless killers,
0:49:13 > 0:49:16the stoat and the cat
0:49:16 > 0:49:21and against them, the kakapo had no defence whatever.
0:49:22 > 0:49:24Very rapidly, its numbers diminished
0:49:24 > 0:49:32until today there are not more than 60 individual kakapo left.
0:49:33 > 0:49:36To give them some chance of survival,
0:49:36 > 0:49:39they've been collected and released on a small offshore island
0:49:39 > 0:49:42that has been cleared of cats.
0:49:42 > 0:49:46But elsewhere, these domestic pets that were brought here to catch mice
0:49:46 > 0:49:51in people's houses have run wild in the forests, and prey on native birds
0:49:51 > 0:49:54which still have not acquired the right reflexes to save themselves
0:49:54 > 0:49:55from its attacks.
0:50:20 > 0:50:24Cats are not the only foreign killers here.
0:50:24 > 0:50:27Ferrets were imported for hunting introduced rabbits.
0:50:27 > 0:50:30They are domesticated polecats.
0:50:30 > 0:50:33Some escaped, reverted to their wild state and bred.
0:50:33 > 0:50:35This one is feeding on a penguin chick
0:50:35 > 0:50:38which must have been an easy victim.
0:50:38 > 0:50:41None of New Zealand's flightless birds are safe from them.
0:50:43 > 0:50:46People also introduced plant-eating animals.
0:50:46 > 0:50:49Possums were brought from Australia as pets.
0:50:56 > 0:50:59Rabbits were also imported to provide meat and fur,
0:50:59 > 0:51:03and to put to good use, as the importers must have thought,
0:51:03 > 0:51:07the abundant grass that was otherwise going to waste.
0:51:07 > 0:51:09And red deer were released in the mountains
0:51:09 > 0:51:11to provide hunters with sport.
0:51:11 > 0:51:15Yet even these seemingly harmless vegetarians had a catastrophic effect
0:51:15 > 0:51:17on the native animals.
0:51:17 > 0:51:22They grazed so effectively that they destroyed the trees and bushes.
0:51:22 > 0:51:25The soil was washed away and the forest devastated.
0:51:25 > 0:51:28So the local creatures were robbed of their cover and vegetation,
0:51:28 > 0:51:30on which they depended.
0:51:31 > 0:51:35The problems of halting this destruction are very great.
0:51:35 > 0:51:38This extraordinary bird is the takahe.
0:51:38 > 0:51:43Like the kakapo, it epitomises the effects of island-living.
0:51:43 > 0:51:46It's become a giant, for it's a rail, like the one in Aldabra,
0:51:46 > 0:51:49and by far the biggest of its family.
0:51:49 > 0:51:52It's unique to these islands, it's flightless,
0:51:52 > 0:51:56and has virtually no defence against invaders.
0:51:56 > 0:51:59At the beginning of this century, it was thought to be extinct.
0:51:59 > 0:52:04Then, after no one had seen a living takahe for over 50 years,
0:52:04 > 0:52:09a small population was discovered in a remote valley in South Island.
0:52:09 > 0:52:12There are about 200 left.
0:52:12 > 0:52:14But they are unlikely to spread,
0:52:14 > 0:52:17for their habitat elsewhere has been destroyed,
0:52:17 > 0:52:19and there is the greatest difficulty
0:52:19 > 0:52:21in getting them to breed in captivity.
0:52:24 > 0:52:29So, unless man is prepared to change his attitude and become
0:52:29 > 0:52:33an active protector as he has done here in New Zealand
0:52:33 > 0:52:36those strange specialised islanders
0:52:36 > 0:52:41are doomed to the fate of the first island-living creature that man
0:52:41 > 0:52:45exterminated and become as dead as the dodo.
0:52:45 > 0:52:48But of course, not all the creatures that you find on islands
0:52:48 > 0:52:51necessarily spend all their time there.
0:52:51 > 0:52:56Some like those tough international travellers over there, the gannets,
0:52:56 > 0:52:58just come here for lodging.
0:53:00 > 0:53:02They, like the frigates and the boobies of Aldabra,
0:53:02 > 0:53:06the noddies and the terns of a thousand tropical atolls,
0:53:06 > 0:53:10find their food, not on the islands where they come to nest, but in the
0:53:10 > 0:53:15surrounding seas, and that is the vast and complex community
0:53:15 > 0:53:18that we'll be looking at next time.