1 00:00:54,755 --> 00:01:00,216 Blue water covers most of our planet, but in it are set tiny specks of land, 2 00:01:00,394 --> 00:01:04,888 some the tips of volcanoes, some mere rings of coral. 3 00:01:05,299 --> 00:01:07,426 They're miniature enclosed worlds 4 00:01:07,601 --> 00:01:14,336 where animals and plants become transformed into new species with extraordinary speed. 5 00:01:40,868 --> 00:01:45,999 If you wanted to pick a really remote desert islan cut off from the rest of the world, 6 00:01:46,173 --> 00:01:47,834 you might well choose this one. 7 00:01:48,309 --> 00:01:51,073 This is Aldabra in the Indian Ocean. 8 00:01:51,312 --> 00:01:57,046 The nearest land in that direction is the coast of Africa, about 250 miles away. 9 00:01:57,918 --> 00:02:01,012 Over there, about the same distance, is Madagascar, 10 00:02:01,255 --> 00:02:05,191 and if you sailed in that direction, you wouldn't hit much 11 00:02:05,359 --> 00:02:09,318 until you got to the coast of Australia 4,000 miles away. 12 00:02:09,563 --> 00:02:14,000 The island is the tip of an extinct submarine volcano 13 00:02:14,168 --> 00:02:20,107 that rises 15,000 feet from the bottom of the Indian Ocean and is capped with coral rock. 14 00:02:20,641 --> 00:02:27,547 When it finally rose above the surface of the sea about 50,000 years ago, it was lifeless, 15 00:02:27,848 --> 00:02:32,148 but now, a mere 50,000 years later, well, just look. 16 00:02:35,055 --> 00:02:39,583 Frigate birds, thousands of them, circle above one end of the island. 17 00:02:39,827 --> 00:02:45,766 They've come from all over the Indian Ocean, even from India itself 2,000 miles away, 18 00:02:45,933 --> 00:02:49,425 to nest on this particular island in the mangroves. 19 00:02:56,777 --> 00:02:59,644 The white-headed birds among them are immatures, 20 00:02:59,913 --> 00:03:03,349 and there are two different species of them, one bigger than the other. 21 00:03:06,186 --> 00:03:11,317 The males inflate their scarlet throat pouches to show that the site is taken, 22 00:03:11,525 --> 00:03:13,117 and to attract the female. 23 00:03:15,663 --> 00:03:20,498 When she arrives, he persuades her to stay with ecstatic shakes of his head. 24 00:03:37,151 --> 00:03:38,982 Red-footed boobies are here, too. 25 00:03:39,286 --> 00:03:43,017 They're great travellers, and their chicks, which are already fledging, 26 00:03:43,190 --> 00:03:47,650 may well be fishing 3,000 or 4,000 miles away within a year. 27 00:03:48,896 --> 00:03:52,662 Noddies nest not on Aldabra but on a neighbouring atoll, 28 00:03:52,833 --> 00:03:56,428 building platforms of seaweed in the Pisonia trees, 29 00:03:56,603 --> 00:04:02,735 and beneath, on the open coral sand, two million sooty terns lay their eggs. 30 00:04:05,412 --> 00:04:09,610 Their vast numbers are an indication of the richness of the surrounding sea. 31 00:04:10,184 --> 00:04:13,847 Every day, the birds take from it many tons of small fish, 32 00:04:14,088 --> 00:04:16,886 little squid and other marine creatures. 33 00:04:24,798 --> 00:04:27,528 The atoll itself provides no food for them. 34 00:04:27,801 --> 00:04:29,928 All a pair of sooty terns seek from it 35 00:04:30,104 --> 00:04:34,939 are a few square inches of dry land on which to place their single egg, 36 00:04:35,109 --> 00:04:40,103 and an absence of cats, rats and all other egg-stealers and chick-eaters 37 00:04:40,280 --> 00:04:43,215 that plague nesting sites on the mainland. 38 00:04:44,418 --> 00:04:47,148 Such security is important to these terns, 39 00:04:47,354 --> 00:04:51,757 for not only do they lay their eggs exposed and unprotected on the ground, 40 00:04:52,059 --> 00:04:55,051 but their young remain flightless for several weeks after hatching 41 00:04:55,229 --> 00:04:58,528 and a hungry cat could cause havoc among them. 42 00:04:59,199 --> 00:05:02,999 So terns find it well worthwhile, for the sake of such security, 43 00:05:03,170 --> 00:05:06,867 to fly hundreds of miles to this island. 44 00:05:22,489 --> 00:05:27,586 The plants that grow on remote islands like Aldabra... how do they get here? 45 00:05:27,928 --> 00:05:30,294 Well, some certainly come by sea. 46 00:05:30,597 --> 00:05:33,088 In a short walk along this high-water mark, 47 00:05:33,267 --> 00:05:37,465 I've picked up already three different kinds of seeds. 48 00:05:37,871 --> 00:05:43,434 Here's the biggest floating seed of them all. This is a coconut. 49 00:05:45,946 --> 00:05:49,347 There's the familiar nut which contains the white flesh, 50 00:05:49,516 --> 00:05:55,648 and this husk, from which we sometimes make coconut mats, is the flotation device. 51 00:05:57,524 --> 00:06:03,121 Nuts like this can float in the sea for up to four months. This one is dead... 52 00:06:04,198 --> 00:06:08,430 ...but here is one that's alive and still sprouting 53 00:06:09,403 --> 00:06:14,170 The green stem springing from the top, a white rootlet striking down underneath. 54 00:06:14,608 --> 00:06:19,636 Under natural conditions, coconuts establish themselves at the head of the beach. 55 00:06:20,047 --> 00:06:24,143 As they grow taller, they lean out over the sand so that when they're full-grown, 56 00:06:24,318 --> 00:06:27,151 their nuts will drop within reach of the high tide 57 00:06:27,321 --> 00:06:31,087 and be washed out to sea to spread to other islands. 58 00:06:33,594 --> 00:06:36,563 A land-living animal also reached here by sea. 59 00:06:36,897 --> 00:06:40,924 The time and place to find it is at night among the coconut groves. 60 00:06:41,301 --> 00:06:46,671 It travelled here as a larva in the same way as the coconuts, floating in the surface waters. 61 00:06:47,007 --> 00:06:49,100 One or two in a million were washed up on the beach 62 00:06:49,276 --> 00:06:55,374 and crawled ashore to live on land among the coconuts, feeding on them. 63 00:06:56,083 --> 00:06:59,246 It's almost the only creature here likely to give you a painful bite, 64 00:06:59,419 --> 00:07:01,250 so it needs tackling with care. 65 00:07:02,689 --> 00:07:04,418 It's the coconut crab. 66 00:07:15,002 --> 00:07:19,098 Its legs are so long that it can embrace the trunk of a coconut palm, 67 00:07:19,273 --> 00:07:22,606 and it has no difficulty in clambering up to the top. 68 00:07:22,976 --> 00:07:25,774 There it cuts down young nuts with its pincers, 69 00:07:25,946 --> 00:07:30,042 and returns to the ground to feed on the soft white coconut flesh. 70 00:07:30,551 --> 00:07:35,488 Crabs as a group are sea-living creatures and breathe in water by means of gills. 71 00:07:35,956 --> 00:07:40,017 To breathe in air, the coconut crab has developed large pouches within its shell 72 00:07:40,193 --> 00:07:43,959 that have moist linings and can act as simple lungs. 73 00:07:44,531 --> 00:07:47,466 But when it breeds, it has to return to the sea. 74 00:07:47,834 --> 00:07:51,201 There it releases its eggs and sperm into the water at high tide, 75 00:07:51,371 --> 00:07:54,363 so that its larvae will circulate through the sea, 76 00:07:54,641 --> 00:07:57,542 and may be washed up on some new island. 77 00:08:06,920 --> 00:08:11,584 One exceptional land animal made the voyage to Aldabra as an adult: 78 00:08:11,758 --> 00:08:15,353 Its most famous inhabitant, the giant tortoise. 79 00:08:16,163 --> 00:08:18,324 Most tortoises are naturally buoyant. 80 00:08:18,565 --> 00:08:24,026 If one on the coast of mainland Africa, grazing among the mangroves, were swept out to sea, 81 00:08:24,204 --> 00:08:28,868 it might survive long enough to be carried by currents to the islands of the Indian Ocean, 82 00:08:29,042 --> 00:08:30,737 and later to spread among them. 83 00:08:30,944 --> 00:08:36,746 That, almost certainly, is how ancestors of the Aldabran giant tortoise reached here. 84 00:08:39,186 --> 00:08:43,247 It's not a very hospitable place for animals like tortoises 85 00:08:43,423 --> 00:08:45,823 that feed on land-living plants. 86 00:08:46,426 --> 00:08:49,259 The coral rock which forms the substance of the island 87 00:08:49,429 --> 00:08:53,729 erodes into a honeycomb of wickedly sharp blades and spikes. 88 00:08:54,768 --> 00:09:00,502 Any creature moving over it has to step with care if it's not to cut itself badly. 89 00:09:13,487 --> 00:09:18,652 Here and there, the rock forms deep pits into which tortoises sometimes tumble. 90 00:09:19,026 --> 00:09:21,460 When that happens, there is no escape, 91 00:09:21,628 --> 00:09:26,895 and the trapped animals, even if they survive the fall, die from starvation 92 00:09:29,369 --> 00:09:34,898 Quite apart from such traps, the island is a harsh, taxing place in which to live. 93 00:09:35,475 --> 00:09:41,175 The tropical sun, beating down on the animals, threatens to bake them alive inside their shells, 94 00:09:41,348 --> 00:09:43,646 and the remains of casualties are common. 95 00:09:48,455 --> 00:09:50,082 So as the day heats up, 96 00:09:50,257 --> 00:09:55,354 the tortoises head determinedly for the few trees that can provide shade. 97 00:09:57,097 --> 00:10:02,831 Here and there on some beaches grow low, windswept Guettarda trees. 98 00:10:03,804 --> 00:10:08,241 By noon, the ground beneath their branches is packed with refugees from the sun, 99 00:10:08,408 --> 00:10:14,210 waiting for the temperature to fall so that they can search for edible leaves. 100 00:10:17,784 --> 00:10:19,979 Birds, too, can overheat. 101 00:10:21,188 --> 00:10:25,852 The frigates swoop over the one almost permanent lagoon of rainwater on the island, 102 00:10:26,026 --> 00:10:28,620 snatching sips from its surface. 103 00:10:55,989 --> 00:10:58,423 Tortoises, too, must have fresh water. 104 00:10:58,725 --> 00:11:00,317 Although they don't drink every day, 105 00:11:00,494 --> 00:11:03,759 they must do every week or so if they're to survive. 106 00:11:21,348 --> 00:11:24,647 Water can also cool an overheated body. 107 00:11:29,556 --> 00:11:31,148 As the dry season progresses, 108 00:11:31,324 --> 00:11:36,057 the water evaporates and the pools get smaller and more crowded. 109 00:12:10,063 --> 00:12:14,397 Many that came here for relief are near the end of their strength. 110 00:12:14,601 --> 00:12:20,039 Some are unable to drag themselves out of the mud, and so die of starvation. 111 00:12:32,285 --> 00:12:37,450 And yet, in spite of all these hardships, the tortoises breed and proliferate. 112 00:12:37,757 --> 00:12:40,988 There are some 150,000 of them on the atoll. 113 00:12:41,628 --> 00:12:46,964 Their staple food is vegetation and they crop the grass right down to the rootstock. 114 00:12:52,505 --> 00:12:55,167 But as island animals everywhere tend to do, 115 00:12:55,408 --> 00:13:00,402 they've broadened their taste in food to include almost anything that is edible, 116 00:13:00,914 --> 00:13:04,315 including the carcasses of their dead companions. 117 00:13:13,727 --> 00:13:17,527 Flesh is too nutritious to be allowed to rot and go to waste 118 00:13:17,697 --> 00:13:20,564 in this land where there is so little to eat. 119 00:13:31,912 --> 00:13:36,815 50,000 years, which is the time, apparently, that Aldabra has been above the sea, 120 00:13:37,083 --> 00:13:40,052 is not a very long time in terms of evolution. 121 00:13:40,353 --> 00:13:43,845 Nonetheless, 50,000 years of isolation on the island 122 00:13:44,024 --> 00:13:48,222 has brought changes to many plants and animals that live here. 123 00:13:48,495 --> 00:13:51,225 They've begun to take on their own character, 124 00:13:51,464 --> 00:13:56,800 so now they differ slightly both from the ancestors which colonised the island 125 00:13:56,970 --> 00:14:00,406 and from their nearest relations elsewhere in the world. 126 00:14:01,608 --> 00:14:05,601 For example, this close-cropped withered turf around me 127 00:14:05,779 --> 00:14:08,907 contains about 20 different species of plants. 128 00:14:09,182 --> 00:14:14,085 All have been relentlessly cropped by giant tortoises like that. 129 00:14:14,354 --> 00:14:18,882 And look, for example, at this little sedge. 130 00:14:19,893 --> 00:14:26,093 Most sedges bear their flowers at the top of stems that rise quite high above the leaves. 131 00:14:26,466 --> 00:14:32,166 Flowers sticking up like this would not survive long on Aldabra. The tortoises would eat them. 132 00:14:32,439 --> 00:14:36,603 These Aldabran sedges bear their flowers and develop their seeds 133 00:14:36,776 --> 00:14:41,713 close to the rootstock where the jaws of the hungry tortoises can't reach them. 134 00:14:43,817 --> 00:14:48,948 The changes that take place in an island species are not always directly useful like that. 135 00:14:49,289 --> 00:14:52,281 Another of Aldabra's plants has changed in a way 136 00:14:52,459 --> 00:14:55,622 that seems to have no practical significance at all. 137 00:14:56,029 --> 00:14:58,691 This is a lily called Lomatophyllum. 138 00:14:58,965 --> 00:15:04,961 It's slightly different in colour from Lomatophyll growing elsewhere, but that's all. 139 00:15:05,238 --> 00:15:07,138 The difference is very trivial. 140 00:15:10,010 --> 00:15:14,811 But some island plants are spectacularly different from their nearest relatives. 141 00:15:15,115 --> 00:15:19,279 Very, very rarely, extraordinary double nuts like this 142 00:15:19,452 --> 00:15:23,718 are washed up on the shores of the coral islands of the Indian Ocean. 143 00:15:23,957 --> 00:15:27,017 For centuries, nobody knew where they came from. 144 00:15:27,260 --> 00:15:31,196 Some said they were produced by fantastic palm trees 145 00:15:31,364 --> 00:15:36,165 that grew under the surface of the sea, so they were called coco-de-mer. 146 00:15:36,403 --> 00:15:41,204 People believed that their kernels could be made into irresistible love potions 147 00:15:41,374 --> 00:15:44,002 and that their shells, when turned into a cup, 148 00:15:44,177 --> 00:15:48,307 would render the most powerful poison harmless. 149 00:15:48,548 --> 00:15:52,484 A single nut like this was literally worth a king's ransom. 150 00:15:52,752 --> 00:15:54,982 It wasn't until the 18th century 151 00:15:55,155 --> 00:15:58,716 that people discovered that the palms that produced these nuts 152 00:15:58,892 --> 00:16:06,196 grew in one tiny group of islands in the Seychelles, some 700 miles from Aldabra. 153 00:16:07,100 --> 00:16:12,595 The largest surviving group of these trees stands on the little island of Praslin. 154 00:16:45,271 --> 00:16:47,762 There are male and female trees. 155 00:16:48,508 --> 00:16:52,205 The males produce small yellow flowers on long spikes, 156 00:16:52,545 --> 00:16:56,777 and on them lives a little gecko, feeding on their nectar and pollen. 157 00:16:57,851 --> 00:17:00,115 Once again, it's an island original, 158 00:17:00,353 --> 00:17:04,551 slightly different in colour from others in neighbouring islands. 159 00:17:06,392 --> 00:17:10,920 The female flowers start as small reddish buds, no bigger than a man's fist, 160 00:17:11,164 --> 00:17:16,192 but they will develop into the biggest seed produced by any plant. 161 00:17:23,209 --> 00:17:26,610 It takes seven years for the nuts to develop, 162 00:17:26,913 --> 00:17:31,782 and when they are mature, they are so large and so heavy 163 00:17:31,951 --> 00:17:34,852 that almost the only way of opening them is with a saw. 164 00:17:35,054 --> 00:17:39,514 Inside, you can see how very different they are from coconuts. 165 00:17:39,792 --> 00:17:42,761 Not only do they have two lobes to them, 166 00:17:42,962 --> 00:17:47,296 but the nut itself is full solid with flesh. 167 00:17:47,534 --> 00:17:52,301 Flesh that is so heavy that these mature nuts won't float in sea water. 168 00:17:52,472 --> 00:17:54,201 Indeed, sea water kills them. 169 00:17:55,341 --> 00:17:57,673 And that means two things. 170 00:17:58,011 --> 00:18:03,643 First of all, that these palms have never been able to spread to other islands, 171 00:18:03,917 --> 00:18:08,149 and secondly, that they must have actually evolved here. 172 00:18:09,122 --> 00:18:12,216 Isolation changes not only plants but animals. 173 00:18:12,425 --> 00:18:18,330 On Aldabra, wandering among the tortoises are sacred ibis with light blue eyes. 174 00:18:18,598 --> 00:18:20,657 Others elsewhere have dark eyes. 175 00:18:20,900 --> 00:18:26,634 The Aldabran ibis breed among themselves and feed on small shore creatures. 176 00:18:27,006 --> 00:18:29,304 Land crabs are far too big to be eaten, 177 00:18:29,475 --> 00:18:32,535 but they have to be pecked to clear them out of the way. 178 00:18:36,749 --> 00:18:41,846 Several species of Aldabran birds have developed slight variations that make them unique. 179 00:18:42,055 --> 00:18:47,493 The kestrel here is slightly smaller than the Madagascar species, but otherwise the same. 180 00:18:47,694 --> 00:18:52,495 The Aldabran sunbird, however, is a little darker than its African relations. 181 00:19:02,175 --> 00:19:06,202 But perhaps the most dramatic and certainly the most endearing quality 182 00:19:06,379 --> 00:19:11,146 brought to some of the birds of Aldabra by isolation is this. 183 00:19:13,152 --> 00:19:16,713 Not only extreme tameness, but flightlessness. 184 00:19:16,923 --> 00:19:19,050 This is the Aldabran rail. 185 00:19:19,425 --> 00:19:21,484 Flying takes a lot of energy. 186 00:19:21,728 --> 00:19:25,630 It's of obvious value when escaping ground-living enemies, 187 00:19:25,798 --> 00:19:29,734 but there are no such enemies on Aldabra or other remote islands. 188 00:19:30,003 --> 00:19:34,633 So some birds that reach such islands by air have given up flying. 189 00:19:34,874 --> 00:19:39,243 Their wing muscles have dwindled and they can't fly even if they wanted to. 190 00:19:39,545 --> 00:19:41,604 The Aldabran rail is only one example. 191 00:19:43,383 --> 00:19:48,184 A kind of pigeon once lived on another island in the Indian Ocean: Mauritius. 192 00:19:48,554 --> 00:19:52,115 It, too, became flightless and grew as big as a turkey. 193 00:19:52,525 --> 00:19:58,157 It was so tame that European sailors were able to kill it with clubs. 194 00:19:58,498 --> 00:20:02,400 They called it the dodo, and in less than 200 years after finding it, 195 00:20:02,568 --> 00:20:04,536 they'd exterminated it. 196 00:20:06,339 --> 00:20:08,364 Grazing alongside the dodo in Mauritius, 197 00:20:08,541 --> 00:20:13,410 and living in other islands in the Indian Ocean as well, were giant tortoises. 198 00:20:13,713 --> 00:20:18,946 They, too, were taken for food by seamen and were exterminated. 199 00:20:19,319 --> 00:20:22,982 But Aldabra is so remote that few ships come near it, 200 00:20:23,156 --> 00:20:26,182 and here alone, the tortoises have survived. 201 00:20:28,594 --> 00:20:33,827 It seems likely that the African ancestors of these creatures were of a normal size, 202 00:20:34,000 --> 00:20:38,460 and that these tortoises became giants as a consequence of living on islands. 203 00:20:41,541 --> 00:20:45,443 Isolation may have had another effect on the tortoises as well. 204 00:20:45,812 --> 00:20:47,973 When African tortoises are threatened, 205 00:20:48,147 --> 00:20:52,447 they behave in the same way as this baby Aldabran tortoise. 206 00:20:52,652 --> 00:20:54,779 They first pull in their head, 207 00:20:54,954 --> 00:20:58,617 and then they pull after it their heavily armoured front legs 208 00:20:58,791 --> 00:21:04,525 so that nothing sticks out and they're comparatively safe from their enemies. 209 00:21:04,764 --> 00:21:08,928 But when the Aldabran tortoise grows up, its proportions change, 210 00:21:09,135 --> 00:21:10,625 as this one's have done. 211 00:21:10,837 --> 00:21:16,639 This one is now so big that these huge legs won't fit into this space, 212 00:21:16,809 --> 00:21:20,108 so that whatever it does, something sticks out. 213 00:21:20,279 --> 00:21:24,409 It's a fair bet that if there was a hyena on the island, 214 00:21:24,584 --> 00:21:27,144 it would make a meal of the giant tortoise. 215 00:21:27,587 --> 00:21:30,988 But there isn't on Aldabra, so this creature's saf 216 00:21:33,326 --> 00:21:36,591 Just why the island tortoises should have grown so huge, 217 00:21:36,763 --> 00:21:40,460 and another species has done the same in the Galapagos islands, 218 00:21:40,633 --> 00:21:42,362 is by no means clear. 219 00:21:43,403 --> 00:21:46,133 It may be that a large animal with big reserves of fat 220 00:21:46,305 --> 00:21:50,332 is better able to survive bad seasons when there's little to eat. 221 00:21:50,643 --> 00:21:53,737 It may even be that with no predators on the island, 222 00:21:53,913 --> 00:21:56,404 these long-lived creatures just go on growing, 223 00:21:56,582 --> 00:22:00,143 but it is not a phenomenon that is restricted to tortoises. 224 00:22:00,386 --> 00:22:06,382 On an island 3,000 miles away from Aldabra, there is another giant reptile. 225 00:22:08,928 --> 00:22:11,795 Komodo is a small island in Indonesia. 226 00:22:12,131 --> 00:22:14,122 From here, back in the 1920s, 227 00:22:14,300 --> 00:22:18,862 came stories of a huge lizard that became known as the Komodo dragon, 228 00:22:19,038 --> 00:22:21,768 and here the dragons still live. 229 00:22:45,565 --> 00:22:47,055 It's not difficult to find them. 230 00:22:47,233 --> 00:22:51,363 All you need is the carcass of a goat, preferably decayed and smelly, 231 00:22:51,537 --> 00:22:54,438 and the scent will attract them from miles around. 232 00:23:25,404 --> 00:23:30,637 It used to be thought that these very big ones were entirely scavengers, 233 00:23:30,810 --> 00:23:33,745 relying on what carrion they could find, 234 00:23:34,013 --> 00:23:39,007 but now we know that actually they are active killers. 235 00:23:39,352 --> 00:23:48,317 They attack and kill goats, young buffalo, and even on occasion, man. 236 00:23:48,961 --> 00:23:52,328 The reason that I can stand here with relative safety 237 00:23:52,498 --> 00:23:57,595 is that their eyesight is not very good, they are almost deaf, 238 00:23:57,770 --> 00:24:01,069 and they rely on their senses, 239 00:24:01,240 --> 00:24:06,143 primarily on that big yellow tongue which flicks out and tastes the air. 240 00:24:08,314 --> 00:24:13,980 So with any luck, the smell of these dead goats is more powerful than mine, 241 00:24:14,153 --> 00:24:15,711 so they will take no notice of me. 242 00:24:17,123 --> 00:24:21,685 They are, in fact, the kings of their island. They are the top predator. 243 00:24:22,094 --> 00:24:25,586 There is nothing here which preys upon them and is bigger, 244 00:24:27,333 --> 00:24:29,995 and nothing with which they have to share their food. 245 00:24:31,504 --> 00:24:36,464 So, from that point of view, there is no reason why they shouldn't grow big. 246 00:24:37,443 --> 00:24:40,970 And the fact is that there is a positive advantage in growing big, 247 00:24:41,147 --> 00:24:46,983 because the big ones are getting the bigger share of the food. 248 00:24:48,487 --> 00:24:53,754 Not only that, but we now know that these big ones eat small ones. 249 00:24:54,660 --> 00:25:00,530 That perhaps is a reason why, in the isolation of their island, 250 00:25:00,800 --> 00:25:04,292 these kings of Komodo have grown so huge. 251 00:25:05,838 --> 00:25:08,170 And they are indeed immense. 252 00:25:08,674 --> 00:25:13,577 They're related to the water monitors of Asia and Africa and the goannas of Australia, 253 00:25:13,846 --> 00:25:15,370 but they are much more massive, 254 00:25:15,548 --> 00:25:21,077 for whereas two-thirds of the length of these other monitors is taken up by a long thin tail, 255 00:25:21,287 --> 00:25:24,222 the dragon's tail is only about half its length. 256 00:25:24,924 --> 00:25:31,420 Big ones like this can weigh up to 100 pounds and grow to over nine feet long. 257 00:25:38,104 --> 00:25:39,765 Komodo is not, like Aldabra, 258 00:25:39,939 --> 00:25:43,272 a coral atoll growing on the drowned tip of a submarine volcano, 259 00:25:43,442 --> 00:25:48,402 but the eroded remains of one that stood many thousands of feet above sea level. 260 00:25:49,882 --> 00:25:53,545 Volcanoes, indeed, have built many of the most isolated islands. 261 00:25:53,786 --> 00:25:57,381 The Hawaiian islands, lying in the eastern Pacific, are all volcanic, 262 00:25:57,556 --> 00:26:00,923 and the biggest and newest of them is still erupting. 263 00:26:29,989 --> 00:26:35,086 Torrents of basaltic lava erupting from vents 10,000 feet up on the mountain 264 00:26:35,261 --> 00:26:38,788 sometimes flow for many miles down the volcano's flanks. 265 00:26:56,749 --> 00:26:59,013 When, eventually, they cool and solidify, 266 00:26:59,185 --> 00:27:02,985 they become vast slopes of black naked rock. 267 00:27:05,658 --> 00:27:10,527 Such areas as this may remain virtually sterile for decades. 268 00:27:13,599 --> 00:27:19,902 Some vents produce vast quantities of granular ash which builds up around them into cones. 269 00:27:20,740 --> 00:27:23,573 Plants have a better chance of getting root on such material, 270 00:27:23,843 --> 00:27:28,246 and within a century or so, the ash slopes may be covered with green. 271 00:27:29,648 --> 00:27:32,947 These high islands collect moisture-laden clouds, 272 00:27:33,119 --> 00:27:36,885 and on the windward side, rain falls very heavily indeed. 273 00:27:37,857 --> 00:27:40,087 Streams flowing down the mountainside 274 00:27:40,259 --> 00:27:45,128 cut through the layers of loosely compacted ash, eroding deep valleys. 275 00:27:45,297 --> 00:27:47,390 So, unlike a coral atoll, 276 00:27:47,566 --> 00:27:51,400 which is a plain platform of coral, sand and rock only a few feet high, 277 00:27:51,570 --> 00:27:54,334 these immense volcanic islands of Hawaii 278 00:27:54,507 --> 00:27:57,738 offered their colonists a great variety of habitat 279 00:27:57,910 --> 00:28:00,470 from high cold slopes of ash on the summits 280 00:28:00,646 --> 00:28:05,345 to well-watered valleys, hot, lush and humid, near sea level, 281 00:28:05,885 --> 00:28:11,016 from new, naked basalt to long-established forest growing on ancient lava flows. 282 00:28:11,290 --> 00:28:18,696 To exploit them, the animal colonists changed not into just one new form, but into a multitude. 283 00:28:21,400 --> 00:28:22,833 This bird, the palila, 284 00:28:23,002 --> 00:28:27,132 is one of a large family of closely related Hawaiian birds, the honeycreepers. 285 00:28:27,540 --> 00:28:31,533 Their ancestors were probably finch-like birds that were swept here, 286 00:28:31,811 --> 00:28:35,008 perhaps by a freak storm many thousands of years ago. 287 00:28:35,247 --> 00:28:38,580 Once here, they developed into over 30 different species, 288 00:28:38,751 --> 00:28:40,946 each with its own diet and habitat. 289 00:28:41,420 --> 00:28:43,388 The palila lives largely on seeds 290 00:28:43,556 --> 00:28:47,925 and has the short, powerful beak needed to open and crack them. 291 00:28:53,165 --> 00:28:58,967 The 'amakihi, while there's no doubt that it and the palila are related, 292 00:28:59,171 --> 00:29:02,572 has a slender beak, suited to picking up small insects 293 00:29:02,741 --> 00:29:05,141 and sipping nectar from shallow flowers. 294 00:29:05,611 --> 00:29:09,570 Some species have developed striking feather colours and adornments. 295 00:29:09,815 --> 00:29:12,682 These enable the male and female to identify one another 296 00:29:12,852 --> 00:29:15,753 so they don't interbreed with near cousins, 297 00:29:15,921 --> 00:29:18,389 and the species becomes increasingly distinct. 298 00:29:19,625 --> 00:29:25,188 So the 'apapane not only has a longer beak to suit its almost exclusive diet of nectar, 299 00:29:25,364 --> 00:29:27,298 but a conspicuous red head. 300 00:29:29,134 --> 00:29:33,093 The 'akohekohe lives on a mixed diet of insects and nectar, 301 00:29:33,272 --> 00:29:37,072 and has developed a little crest of white feathers at the base of its beak. 302 00:29:41,413 --> 00:29:45,713 The 'i'iwi is scarlet and has a particularly long curved bill 303 00:29:45,885 --> 00:29:49,446 that allows it to probe deep into trumpet-shaped flowers 304 00:29:49,622 --> 00:29:52,386 such as giant lobelias and bananas. 305 00:30:02,735 --> 00:30:06,933 And perhaps most engaging of all, the akiapolaau, 306 00:30:07,106 --> 00:30:09,597 with a splendid dual-purpose beak, 307 00:30:09,775 --> 00:30:13,711 the lower mandible pick-like to chip away bark to find insects, 308 00:30:13,879 --> 00:30:18,578 and an upper mandible elongated into a probe with which to winkle them out. 309 00:30:22,521 --> 00:30:26,082 It's located a beetle larva burrowing away within the bark. 310 00:30:26,392 --> 00:30:31,557 Look how dexterously it uses the two halves of its beak for these different purposes. 311 00:30:45,177 --> 00:30:49,910 The situation amongst Hawaii's insects is even more extreme than it is among its birds. 312 00:30:50,249 --> 00:30:54,948 There is a kind of fly called Drosophila. It's found in many parts of the world. 313 00:30:55,120 --> 00:30:58,817 In North America, for example, there are about 200 species, 314 00:30:58,991 --> 00:31:04,793 but in these tiny islands of Hawaii, there are at least 800. 315 00:31:05,698 --> 00:31:09,259 It seems that soon after the islands' formation, 316 00:31:09,435 --> 00:31:14,168 one or at most two species of Drosophila reached the islands, 317 00:31:14,340 --> 00:31:18,936 and they found the same situation as the honeycreepers found, a lot of vacant niches. 318 00:31:19,178 --> 00:31:23,512 And so they evolved to fill them, and they are now Drosophila, 319 00:31:23,682 --> 00:31:29,382 the larvae of which feed on fruit or rotting leaves or fungi, 320 00:31:29,555 --> 00:31:32,217 or bark or even spiders' eggs. 321 00:31:32,591 --> 00:31:38,393 But now the situation becomes more complex because in Hawaii, there are lava flows like this, 322 00:31:38,931 --> 00:31:44,699 and such lava flows often isolate patches of ancient forest like that over there, 323 00:31:44,903 --> 00:31:47,064 and in one small patch of forest, 324 00:31:47,306 --> 00:31:53,575 there may well be one particular species of Drosophila that occurs nowhere else. 325 00:32:16,935 --> 00:32:19,631 And there are some just there. 326 00:32:29,314 --> 00:32:33,910 These particular ones belong to a group which have evolved, in their isolation, 327 00:32:34,086 --> 00:32:36,054 an extraordinary courtship behaviour, 328 00:32:36,221 --> 00:32:39,384 just as some honeycreepers have evolved bright colours. 329 00:32:39,925 --> 00:32:42,951 It's an insect equivalent of the arena display of antelope. 330 00:32:43,128 --> 00:32:48,828 The males maintain tiny territories and display and battle with one another. 331 00:32:49,368 --> 00:32:53,327 Instead of antlers, they've developed heads shaped like mallets. 332 00:33:02,181 --> 00:33:06,174 In another species, the male courts the female by hoisting his abdomen over his back 333 00:33:06,351 --> 00:33:09,343 and showering her with an aphrodisiac perfume. 334 00:33:12,224 --> 00:33:15,682 Isolation has also affected the wings of Hawaiian insects. 335 00:33:15,894 --> 00:33:17,885 Flying on an island is dangerous. 336 00:33:18,130 --> 00:33:20,360 It risks being blown out to sea, 337 00:33:21,967 --> 00:33:25,095 and this extraordinary bug never takes to the air. 338 00:33:25,571 --> 00:33:29,507 Its wings are tiny, and used only for flirting in courtship. 339 00:33:32,878 --> 00:33:35,005 This lacewing can't even use them for that. 340 00:33:35,280 --> 00:33:38,215 Its wings have become fused together to form a shell. 341 00:33:39,017 --> 00:33:42,714 The Hawaiian cranefly has lost its wings completely. 342 00:33:43,355 --> 00:33:46,222 This cranefly's taste for fruit is typical of its family, 343 00:33:46,391 --> 00:33:49,383 but other insects have changed their feeding habits. 344 00:33:49,695 --> 00:33:53,358 This flightless bug has adopted the hunting techniques of the mantis 345 00:33:53,532 --> 00:33:55,625 which never naturally reached the island. 346 00:33:58,804 --> 00:34:01,136 And this fly is going to get a shock. 347 00:34:04,076 --> 00:34:07,273 The twig caterpillar doesn't, like most twig caterpillars elsewhere, 348 00:34:07,446 --> 00:34:10,040 feed on leaves, but has become a carnivore. 349 00:34:21,360 --> 00:34:24,761 It detected the fly with tiny hairs on its back en 350 00:34:25,030 --> 00:34:29,433 They trigger the caterpillar to arch backwards and pounce on whatever touched it. 351 00:34:33,605 --> 00:34:38,099 So isolation, by restricting the kinds of creature that reached Hawaii, 352 00:34:38,277 --> 00:34:44,147 allows those that did great freedom to develop into different and unexpected forms. 353 00:34:47,252 --> 00:34:52,280 Human beings, the Polynesians, reached Hawaii several thousand years ago. 354 00:34:52,658 --> 00:34:55,354 When Europeans arrived, they found to their surprise 355 00:34:55,527 --> 00:34:59,190 an unknown people with an elaborate and splendid culture. 356 00:34:59,798 --> 00:35:01,663 The Hawaiians were superb seamen. 357 00:35:01,967 --> 00:35:04,026 They not only paddled dugout canoes, 358 00:35:04,203 --> 00:35:09,368 but sailed immense ocean-going double canoes that could carry several hundred passengers, 359 00:35:09,641 --> 00:35:13,668 and that tradition survives still in many parts of the Pacific. 360 00:35:25,023 --> 00:35:30,620 The last of the really big canoes must have disappeared about 100 years ago, 361 00:35:30,862 --> 00:35:33,524 but still, in the remoter parts of the Pacific, 362 00:35:33,765 --> 00:35:37,496 people remembered the techniques that were used to sail them, 363 00:35:37,669 --> 00:35:41,161 and still practise the skills needed to build them 364 00:35:41,506 --> 00:35:45,340 This particular canoe, which is very big for modern times, 365 00:35:45,544 --> 00:35:51,505 was built on the tiny island of Ribono in Kiribati the islands that used to be called the Gilberts. 366 00:35:51,817 --> 00:35:57,881 It is only about 50 feet long, enormous for today, but only half the size of the old canoes, 367 00:35:58,056 --> 00:36:04,120 and still the people are prepared to sail on journeys of up to 1,000 miles in it. 368 00:36:04,363 --> 00:36:10,199 The techniques for building it are those that were used for the old canoes. 369 00:36:10,435 --> 00:36:12,300 The lashings, for instance. 370 00:36:12,504 --> 00:36:15,439 They are made from the fibres of coconut husks. 371 00:36:15,974 --> 00:36:18,704 Clumps are teased out, rolled and twisted 372 00:36:18,877 --> 00:36:21,368 so that each fibre binds with its neighbours. 373 00:36:21,647 --> 00:36:25,879 It is a repetitious job, but a skilled one if the string is going to be strong, 374 00:36:26,051 --> 00:36:28,986 and it is taken on by the women and the old people. 375 00:36:29,221 --> 00:36:33,089 Hundreds of yards will be needed to build a big canoe. 376 00:36:39,798 --> 00:36:42,733 It's used not only for lashing one spar to another 377 00:36:42,901 --> 00:36:47,565 but for sewing together the planks that form the sides of the big canoes. 378 00:37:13,432 --> 00:37:18,233 The Pandanus tree produces strap-like leaves, which, when dried and split, 379 00:37:18,403 --> 00:37:23,966 provide ribbons that are woven into strong and durable mats to serve as sails. 380 00:37:33,318 --> 00:37:35,809 So if you have the necessary knowledge and skill, 381 00:37:35,987 --> 00:37:41,948 even a small atoll can provide all the materials to build an ocean-going canoe. 382 00:37:42,861 --> 00:37:46,297 In such craft, the Polynesians travelled right across the Pacific. 383 00:37:46,765 --> 00:37:50,565 For a long time, Europeans, so proud of their navigating skills, 384 00:37:50,736 --> 00:37:53,728 maintained that the Polynesian voyages were accidental, 385 00:37:53,905 --> 00:37:56,271 made when fishing canoes were blown off course. 386 00:37:56,842 --> 00:38:03,042 But the huge canoes carried women and children, and were loaded with plants and animals, 387 00:38:03,215 --> 00:38:06,480 with every intention of founding new colonies. 388 00:38:07,953 --> 00:38:12,617 The Polynesian navigators had and have the most astonishing powers of observation 389 00:38:12,791 --> 00:38:14,383 by which they find their way. 390 00:38:15,427 --> 00:38:18,123 A particular kind of bird during one season of the year 391 00:38:18,296 --> 00:38:20,890 will always travel in a certain direction. 392 00:38:21,500 --> 00:38:26,199 Some birds are ocean-goers, others seldom travel far from their nesting grounds, 393 00:38:26,371 --> 00:38:30,774 so spotting one can indicate that there's land close by, 394 00:38:30,942 --> 00:38:33,274 and following it may take you there. 395 00:38:36,448 --> 00:38:38,075 Distant islands can be detected 396 00:38:38,250 --> 00:38:41,686 by their effect on the ripples on the surface of the sea. 397 00:38:42,721 --> 00:38:45,519 Tall islands trail clouds of characteristic shape 398 00:38:45,690 --> 00:38:48,124 like smoke from a chimney blown by the wind, 399 00:38:48,293 --> 00:38:50,261 and since they are so high in the sky, 400 00:38:50,429 --> 00:38:54,991 they can be recognised and identified long before the island is visible. 401 00:38:56,368 --> 00:39:01,237 Using such techniques and observing the sun and stars, the pattern of the winds, 402 00:39:01,406 --> 00:39:04,637 and feeling through the rudder the movements of swells and currents, 403 00:39:04,810 --> 00:39:07,802 the Polynesians colonised island after island. 404 00:39:08,180 --> 00:39:10,444 Their original home was in the western Pacific. 405 00:39:10,615 --> 00:39:15,780 They reached the Tahitian islands, in the centre of the ocean, over 2,000 years ago. 406 00:39:18,790 --> 00:39:22,749 They sailed so far eastward that they reached Easter Island, 407 00:39:22,928 --> 00:39:25,658 three-quarters of the way to the coast of South America. 408 00:39:27,332 --> 00:39:30,460 Those that settled here seem to have been more isolated than most, 409 00:39:30,635 --> 00:39:35,470 and, like so many other islanders, they developed their own culture. 410 00:39:35,907 --> 00:39:39,104 They carved the rocks of their headlands into strange shapes. 411 00:39:39,678 --> 00:39:42,306 On the flanks of the great volcano that built their island, 412 00:39:42,481 --> 00:39:48,317 they set up huge images whose enigmatic faces have haunted the European imagination 413 00:39:48,487 --> 00:39:52,583 ever since they were discovered by westerners two centuries ago. 414 00:40:04,636 --> 00:40:06,763 The heyday of the Easter Island culture 415 00:40:06,938 --> 00:40:10,396 seems to have been passed long before Europeans arrived, 416 00:40:10,709 --> 00:40:16,648 for many statues were overturned and some lay half-finished and abandoned 417 00:40:16,815 --> 00:40:19,375 where they had been carved in the quarries. 418 00:40:29,794 --> 00:40:33,560 The scale of these Polynesian voyages is difficult to imagine. 419 00:40:33,798 --> 00:40:39,361 From their headquarters in Samoa to their most northerly colony in Hawaii, 420 00:40:39,538 --> 00:40:43,838 which they reached by way of the Marquesas, was some 5,000 miles. 421 00:40:44,709 --> 00:40:48,770 The journey to Easter Island, about 3,300 miles. 422 00:40:49,214 --> 00:40:51,148 But the most extraordinary voyage of all 423 00:40:51,316 --> 00:40:56,754 took them across 4,000 miles of open ocean, south to New Zealand. 424 00:40:58,290 --> 00:41:01,589 The group that landed here, ancestors of the Maori, 425 00:41:01,760 --> 00:41:05,025 arrived about 1,500 years ago. 426 00:41:05,964 --> 00:41:09,195 The land they discovered must have been a great surprise to them, 427 00:41:09,367 --> 00:41:13,463 for it was very different from the tropical island from which they had come. 428 00:41:14,272 --> 00:41:16,968 For much of the year, it was bitterly cold. 429 00:41:17,976 --> 00:41:22,470 In the South Island stood great mountain ranges covered with snow and ice 430 00:41:22,647 --> 00:41:25,309 that the Maori can never have seen before. 431 00:41:26,918 --> 00:41:31,878 Not only that, but the forests were far richer in animals and plants 432 00:41:32,057 --> 00:41:34,321 than any island they had yet discovered. 433 00:41:34,793 --> 00:41:38,991 That was because these islands had a very different origin and history. 434 00:41:40,131 --> 00:41:44,295 They were neither flat coral atolls nor were they the tips of volcanoes 435 00:41:44,469 --> 00:41:49,497 that had risen above the surface of the Pacific in comparatively recent geological time. 436 00:41:50,375 --> 00:41:52,935 These islands of New Zealand were ancient lands. 437 00:41:53,111 --> 00:41:55,102 Fragments of a great supercontinent 438 00:41:55,280 --> 00:41:59,614 of which Australia, Antarctica and South America had been a part. 439 00:41:59,951 --> 00:42:04,786 In consequence, they had on them many more different kinds of animals 440 00:42:04,956 --> 00:42:06,753 than other more recent islands. 441 00:42:07,025 --> 00:42:09,858 They had animals like this. 442 00:42:11,396 --> 00:42:13,523 This is the tuatara. 443 00:42:13,932 --> 00:42:19,666 It's a reptile, it's nocturnal and solitary, and it's a flesh-eater. 444 00:42:20,005 --> 00:42:25,705 It feeds on insects, earthworms and even young nestling birds. 445 00:42:26,411 --> 00:42:31,110 It might look like a lizard, but it's a more ancient creature than that, 446 00:42:31,282 --> 00:42:33,648 more closely related to the early dinosaurs 447 00:42:33,818 --> 00:42:36,150 than it is to the modern family of lizards. 448 00:42:36,488 --> 00:42:40,822 Once creatures like it must have swarmed over that great supercontinent, 449 00:42:40,992 --> 00:42:44,393 but New Zealand split away from the supercontinent 450 00:42:44,562 --> 00:42:46,621 before the great expansion of the early mammals 451 00:42:46,798 --> 00:42:50,996 which ultimately led to the extinction of most of the early reptiles. 452 00:42:51,202 --> 00:42:56,196 Only in New Zealand did the tuatara remain safe. 453 00:42:56,908 --> 00:43:01,675 And New Zealand also has been a sanctuary for another early creature. 454 00:43:03,815 --> 00:43:07,273 The kiwi. It's a bird, but what an odd one. 455 00:43:07,585 --> 00:43:11,851 It has no visible wings and no tail and lives in a burrow. 456 00:43:16,461 --> 00:43:20,488 There, it produces a single and enormous egg. 457 00:43:27,872 --> 00:43:29,737 Flightless, living in burrows, 458 00:43:29,908 --> 00:43:33,867 with feathers so long and loose they look like shaggy fur, 459 00:43:34,045 --> 00:43:38,243 and running quietly across the forest floor at night in search of food, 460 00:43:38,450 --> 00:43:43,012 this odd animal could be considered a kind of bird equivalent of a mammal. 461 00:43:43,455 --> 00:43:46,982 Indeed, the kiwi does play that role in these islands 462 00:43:47,258 --> 00:43:50,887 where originally there were no land mammals of any kind. 463 00:43:59,871 --> 00:44:03,967 It has, however, retained that characteristic possession of the bird, a beak... 464 00:44:06,044 --> 00:44:07,705 ...and it uses it to collect worms, 465 00:44:07,879 --> 00:44:12,543 plunging it deep into the earth to smell for them as a mammal does. 466 00:44:16,321 --> 00:44:20,655 The ancestors of the kiwi were flightless before New Zealand was isolated, 467 00:44:20,825 --> 00:44:22,759 for the kiwi is a ratite. 468 00:44:23,862 --> 00:44:27,229 Other members of that family of ancient flightless birds 469 00:44:27,398 --> 00:44:30,697 still survive on other fragments of the great supercontinent. 470 00:44:30,869 --> 00:44:36,171 There's the ostrich in Africa, the rhea in South America and the emu in Australia. 471 00:44:36,508 --> 00:44:38,908 All those are bigger than the kiwi, 472 00:44:39,077 --> 00:44:42,569 but the kiwi once had a cousin living here in New Zealand 473 00:44:42,747 --> 00:44:44,647 that was bigger than the lot of them. 474 00:44:44,916 --> 00:44:50,047 It was probably the tallest bird that has ever existed, the moa. 475 00:44:51,689 --> 00:44:55,216 Its bones have been found in great numbers here in New Zealand. 476 00:44:55,393 --> 00:45:01,127 Often in between the ribs have been found piles of polished pebbles. 477 00:45:01,332 --> 00:45:07,168 They were the stones from the gizzard with which the moa ground up its food, 478 00:45:07,338 --> 00:45:14,437 and from the vegetable remains, we know that it ate fruit, twigs and the leaves of trees. 479 00:45:16,414 --> 00:45:20,646 There were a dozen or so different species of moa of varying sizes. 480 00:45:22,287 --> 00:45:24,687 This particular one was the biggest of all. 481 00:45:24,989 --> 00:45:27,958 It was not the heaviest bird that has ever lived, 482 00:45:28,159 --> 00:45:32,186 its relative, the extinct elephant bird that lived in Madagascar was that, 483 00:45:32,363 --> 00:45:37,232 but its weight nonetheless was substantial, about 520 pounds, 484 00:45:37,402 --> 00:45:42,772 and it was the tallest of all birds, standing over 13 feet high. 485 00:45:43,308 --> 00:45:46,300 In fact, it was the bird equivalent of a giraffe. 486 00:45:48,847 --> 00:45:54,251 This is the mummified head and neck of one of the smaller species of moa, 487 00:45:54,519 --> 00:45:59,013 and it suggests, because many necks have been found attached to heads, 488 00:45:59,257 --> 00:46:01,521 that the Maori had so much moa meat 489 00:46:01,693 --> 00:46:06,096 that they could afford to throw away sections like this. 490 00:46:06,564 --> 00:46:10,398 The Maori not only reduced the number of moa by hunting, 491 00:46:10,568 --> 00:46:14,937 they also burnt down the forests on which the moas depended. 492 00:46:15,206 --> 00:46:20,166 And so, by the time the Europeans arrived here in the 18th century, 493 00:46:20,345 --> 00:46:24,042 the last of the moas had been extinct for some 200 years. 494 00:46:26,584 --> 00:46:31,817 But in the millions of years that have passed since New Zealand was isolated as islands, 495 00:46:32,023 --> 00:46:35,151 many more modern creatures have arrived here. 496 00:46:35,360 --> 00:46:40,354 They've got here, as they've managed to get to islands all over the world, by flying. 497 00:46:41,766 --> 00:46:44,257 Some have changed only a little since they arrived. 498 00:46:44,435 --> 00:46:48,337 The kereru is still quite clearly a kind of pigeon 499 00:46:55,013 --> 00:46:58,881 And this, the kea, is still recognisably a parrot. 500 00:46:59,951 --> 00:47:01,816 Its ancestors came, doubtless, 501 00:47:01,986 --> 00:47:06,116 from that great parrot homeland, Australia, 1,000 miles away. 502 00:47:06,291 --> 00:47:09,818 Since it's been here, it's probably changed its habits a good deal, 503 00:47:09,994 --> 00:47:12,588 for it's taken up life in the cold, high mountains 504 00:47:12,764 --> 00:47:17,201 where it feeds on berries and roots, buds and insects. 505 00:47:26,210 --> 00:47:30,408 It has also, with that adaptability of diet characteristic of islanders, 506 00:47:30,581 --> 00:47:32,549 become a general scavenger, 507 00:47:32,750 --> 00:47:36,516 and will even feed on carrion like a crow or small vulture. 508 00:47:38,489 --> 00:47:42,983 One parrot, here, however, has been changed extremely by island life. 509 00:47:43,962 --> 00:47:45,293 The kakapo. 510 00:47:45,797 --> 00:47:48,732 There are no ground-living leaf-eating mammals on the island, 511 00:47:48,900 --> 00:47:52,392 so this has become a kind of parrot-equivalent of a rabbit. 512 00:47:56,074 --> 00:48:01,535 It's extremely nervous, nocturnal, and it lives on vegetation, 513 00:48:01,746 --> 00:48:07,013 but it shows those two characteristics of island-living creatures. 514 00:48:07,752 --> 00:48:10,653 It has lost its powers of flight, 515 00:48:11,022 --> 00:48:17,393 so its only defence is to freeze motionless as it's doing now. 516 00:48:18,463 --> 00:48:21,557 And secondly, it's a giant. 517 00:48:22,467 --> 00:48:26,062 It's the biggest of all the parrots by weight. 518 00:48:27,305 --> 00:48:31,241 A big one can weigh over three kilos. 519 00:48:32,810 --> 00:48:39,648 It also shows only too vividly a third characteristic of island-living forms: 520 00:48:40,451 --> 00:48:43,147 Their extreme vulnerability. 521 00:48:43,588 --> 00:48:49,686 When their islands are invaded by outsiders, they often have no defence. 522 00:48:50,528 --> 00:48:55,192 The kakapo's troubles started when the Polynesians first came to New Zealand. 523 00:48:55,566 --> 00:49:00,503 They brought a kind of rat which may have preyed upon the nestling kakapo, 524 00:49:00,671 --> 00:49:04,072 and the Polynesians themselves hunted it. 525 00:49:05,376 --> 00:49:09,710 The real catastrophe came when Europeans arrived, 526 00:49:09,881 --> 00:49:16,480 because they brought with them those two merciless killers, the stoat and the cat 527 00:49:17,088 --> 00:49:21,548 Against them, the kakapo had no defence whatever. 528 00:49:22,527 --> 00:49:25,325 Very rapidly, its numbers diminished 529 00:49:25,496 --> 00:49:32,493 until today there are not more than 60 individual kakapo left. 530 00:49:34,238 --> 00:49:36,263 To give them some chance of survival, 531 00:49:36,541 --> 00:49:41,911 they've been taken to a small offshore island that has been cleared of cats. 532 00:49:42,713 --> 00:49:47,980 Elsewhere, these domestic pets that were brought here to catch mice in houses 533 00:49:48,152 --> 00:49:51,519 have run wild in the forests, and prey on native birds 534 00:49:51,689 --> 00:49:56,422 which have not acquired the right reflexes to save themselves from its attacks. 535 00:50:21,385 --> 00:50:24,411 Cats are not the only foreign killers here. 536 00:50:24,689 --> 00:50:27,658 Ferrets were imported for hunting introduced rabbits. 537 00:50:28,092 --> 00:50:30,424 They are domesticated polecats. 538 00:50:30,728 --> 00:50:33,720 Some escaped, reverted to their wild state and bred. 539 00:50:34,165 --> 00:50:38,431 This one is feeding on a penguin chick which must have been an easy victim. 540 00:50:38,603 --> 00:50:42,403 None of New Zealand's flightless birds are safe from them. 541 00:50:44,342 --> 00:50:46,902 People also introduced plant-eating animals. 542 00:50:47,345 --> 00:50:50,314 Possums were brought from Australia as pets. 543 00:50:56,521 --> 00:51:00,184 Rabbits were also imported to provide meat and fur, 544 00:51:00,491 --> 00:51:03,892 and to put to good use, as the importers must have thought, 545 00:51:04,162 --> 00:51:07,427 the abundant grass that was going to waste. 546 00:51:07,899 --> 00:51:11,995 And red deer were released in the mountains to provide hunters with sport. 547 00:51:12,303 --> 00:51:17,707 Yet these seemingly harmless vegetarians had a catastrophic effect on the native animals. 548 00:51:18,409 --> 00:51:22,675 They grazed so effectively that they destroyed the trees and bushes. 549 00:51:22,914 --> 00:51:26,042 The soil was washed away and the forest devastated. 550 00:51:26,217 --> 00:51:30,847 Creatures were robbed of their cover and vegetation. 551 00:51:32,290 --> 00:51:35,555 The problems of halting this destruction are very great. 552 00:51:35,860 --> 00:51:39,091 This extraordinary bird is the takahe. 553 00:51:39,430 --> 00:51:43,389 Like the kakapo, it epitomises the effects of island-living. 554 00:51:43,634 --> 00:51:47,161 It's become a giant, for it's a rail, like the one in Aldabra, 555 00:51:47,338 --> 00:51:49,329 and the biggest of its family. 556 00:51:49,607 --> 00:51:52,701 It's unique to these islands, it's flightless, 557 00:51:52,877 --> 00:51:56,278 and has virtually no defence against invaders. 558 00:51:56,747 --> 00:51:59,807 At the beginning of this century, it was thought to be extinct. 559 00:52:00,117 --> 00:52:04,577 Then, after no one had seen a living takahe for over 50 years, 560 00:52:04,755 --> 00:52:09,556 a small population was discovered in a remote valley in South Island. 561 00:52:10,494 --> 00:52:12,860 There are about 200 left. 562 00:52:13,197 --> 00:52:17,827 They are unlikely to spread, for their habitat elsewhere has been destroyed, 563 00:52:18,069 --> 00:52:21,869 and there is the greatest difficulty in getting them to breed in captivity. 564 00:52:24,976 --> 00:52:31,506 So, unless man is prepared to change his attitude and become an active protector 565 00:52:31,816 --> 00:52:33,511 as he has done here in New Zealand, 566 00:52:33,751 --> 00:52:36,618 those strange specialised islanders 567 00:52:36,787 --> 00:52:41,884 are doomed to the fate of the first island-living creature that man exterminated 568 00:52:42,059 --> 00:52:45,222 and become as dead as the dodo. 569 00:52:45,863 --> 00:52:48,491 Of course, not all the creatures that you find on islands 570 00:52:48,666 --> 00:52:51,430 necessarily spend all their time there. 571 00:52:51,736 --> 00:52:56,867 Some like those tough international travellers over there, the gannets, 572 00:52:57,041 --> 00:52:59,066 just come here for lodging. 573 00:53:00,578 --> 00:53:03,240 They, like the frigates and the boobies of Aldabra, 574 00:53:03,414 --> 00:53:06,542 the noddies and the terns of a thousand tropical atolls, 575 00:53:06,717 --> 00:53:12,451 find their food, not on the islands where they come to nest, but in the surrounding seas, 576 00:53:12,757 --> 00:53:18,821 and that is the vast and complex community that we'll be looking at next time.