1 00:00:36,000 --> 00:00:39,400 About 340 million years ago, 2 00:00:39,400 --> 00:00:43,760 a brand-new family of animals was evolving in the primeval swamps. 3 00:00:48,840 --> 00:00:52,880 They were to go one step further than the amphibians, 4 00:00:52,880 --> 00:00:55,240 who had emerged onto dry land before them. 5 00:00:57,160 --> 00:01:02,360 For they would eventually completely cut their ties with water. 6 00:01:04,000 --> 00:01:08,760 They were the ancestors of today's lizards. 7 00:01:12,080 --> 00:01:18,280 They evolved scaly, impermeable skins and moved up into the forests. 8 00:01:33,440 --> 00:01:37,680 They diversified into a multitude of different shapes and sizes. 9 00:01:43,920 --> 00:01:48,120 They developed signalling systems to communicate with one another. 10 00:01:55,400 --> 00:02:00,960 And they squabbled as animals do over mates and territory. 11 00:02:00,960 --> 00:02:05,160 For food, they hunted insects 12 00:02:05,160 --> 00:02:10,840 that were already well-established on the land in great numbers. 13 00:02:15,880 --> 00:02:20,760 And here, without returning to water, they produced their families. 14 00:02:27,920 --> 00:02:31,520 They powered their bodies not only with food 15 00:02:31,520 --> 00:02:34,800 but with the heat that they drew directly from the sun. 16 00:02:38,520 --> 00:02:40,120 As they diversified, 17 00:02:40,120 --> 00:02:44,560 so they spread into the harshest of the land's habitats, 18 00:02:44,560 --> 00:02:46,480 the baking, waterless deserts, 19 00:02:46,480 --> 00:02:49,720 which eventually, they would come to dominate. 20 00:02:54,360 --> 00:02:58,640 The bigger ones are truly powerful and fierce. 21 00:02:58,640 --> 00:03:02,000 Rearing up, they're well able to defend themselves 22 00:03:02,000 --> 00:03:04,880 with their front legs if they're threatened. 23 00:03:07,600 --> 00:03:13,120 This is a very intelligent animal. 24 00:03:13,120 --> 00:03:19,240 It is observing me just as I am observing it. 25 00:03:19,240 --> 00:03:21,560 It's a monitor lizard 26 00:03:21,560 --> 00:03:26,640 and it's king of this country, the Australian outback. 27 00:03:26,640 --> 00:03:32,120 It is frightened of pretty well nothing, obviously including me, 28 00:03:32,120 --> 00:03:37,960 and it will chase and hunt and eat pretty well anything. 29 00:03:37,960 --> 00:03:41,840 There are several thousand lizards round the world 30 00:03:41,840 --> 00:03:46,760 and they are truly the dragons of the dry. 31 00:04:01,200 --> 00:04:05,560 Their eggs on land had to be encased in shells 32 00:04:05,560 --> 00:04:08,960 to prevent them from drying out. 33 00:04:08,960 --> 00:04:12,280 And what better place to lay them could a mother lizard find 34 00:04:12,280 --> 00:04:15,240 than a termite's nest? 35 00:04:15,240 --> 00:04:20,000 Worker termites labour unceasingly to keep the temperature and humidity 36 00:04:20,000 --> 00:04:22,920 virtually constant for their own benefit. 37 00:04:22,920 --> 00:04:29,240 But that also makes their mound a near-perfect incubator for eggs of others. 38 00:04:33,240 --> 00:04:36,880 After ten months, they're beginning to hatch. 39 00:04:55,880 --> 00:04:59,440 These are baby lace monitors. 40 00:05:10,680 --> 00:05:12,680 But they face a major problem. 41 00:05:12,680 --> 00:05:17,920 A termite nest's walls can be a foot thick and extremely hard, 42 00:05:17,920 --> 00:05:20,800 too hard for the young monitors to break through. 43 00:05:20,800 --> 00:05:23,960 They are imprisoned with no food. 44 00:05:30,320 --> 00:05:34,760 For a week after hatching, they are sustained by the last of the yolk 45 00:05:34,760 --> 00:05:36,440 that remains in their stomachs. 46 00:05:36,440 --> 00:05:39,800 But when that comes to an end, they could starve. 47 00:05:47,840 --> 00:05:51,320 An adult lace monitor is nearby. 48 00:05:58,600 --> 00:06:02,120 It may or may not be the baby's mother. 49 00:06:02,120 --> 00:06:06,280 If not, then it could be a threat, for monitors are hunters 50 00:06:06,280 --> 00:06:10,440 and will eat most small animals, including baby lizards. 51 00:06:16,120 --> 00:06:20,080 She's nearing the termite nest within which the young are trapped. 52 00:06:29,480 --> 00:06:32,560 She could be looking for a place to lay her eggs. 53 00:06:32,560 --> 00:06:38,040 Alternatively, she might be searching for food, such as little lizards. 54 00:07:12,600 --> 00:07:15,360 The babies are released unharmed. 55 00:07:15,360 --> 00:07:18,160 Perhaps she is indeed the babies' mother, 56 00:07:18,160 --> 00:07:21,600 and not only remembered exactly where she laid her eggs a year ago, 57 00:07:21,600 --> 00:07:26,160 but knew that her babies would need her help to escape from their incubator. 58 00:07:32,000 --> 00:07:33,720 The young, however, are free. 59 00:07:33,720 --> 00:07:37,040 But the outside world is a dangerous place. 60 00:07:43,080 --> 00:07:46,480 They head for safety, up into the trees. 61 00:07:51,240 --> 00:07:54,480 In the branches, there are other kinds of lizards. 62 00:07:56,000 --> 00:07:58,000 Jacky dragons. 63 00:07:58,000 --> 00:08:03,520 Each has its own territory and warns others to keep out. 64 00:08:03,520 --> 00:08:06,480 A wave of the front leg and a bob of the head 65 00:08:06,480 --> 00:08:08,960 is a Jacky dragon's way of claiming territory. 66 00:08:08,960 --> 00:08:12,920 Here, the action is slowed down. 67 00:08:12,920 --> 00:08:14,960 In reality, the leg flick is so swift 68 00:08:14,960 --> 00:08:20,600 it's hard for us to see, but it's very plain to another Jacky dragon. 69 00:08:23,720 --> 00:08:27,080 But sometimes, signals are not enough. 70 00:08:27,080 --> 00:08:29,600 Physical violence is needed. 71 00:08:47,440 --> 00:08:50,520 He's won. The vanquished acknowledges his defeat 72 00:08:50,520 --> 00:08:56,120 with a different signal - a slow leg wave with no head bob. 73 00:08:58,240 --> 00:09:03,880 The winner returns to his territory in the branches and announces his victory... 74 00:09:05,400 --> 00:09:07,800 ..which his neighbour acknowledges. 75 00:09:14,640 --> 00:09:19,600 So now both can live alongside one another in peace. 76 00:09:23,280 --> 00:09:26,080 Once Jacky dragons stop signalling, 77 00:09:26,080 --> 00:09:29,000 it's quite hard to spot them up in the branches. 78 00:09:30,240 --> 00:09:36,520 American anoles are so well camouflaged that they are virtually invisible. 79 00:09:36,520 --> 00:09:41,480 There is one on this tree right in front of me. 80 00:09:41,480 --> 00:09:46,000 But he too needs to draw attention to himself to warn off rivals 81 00:09:46,000 --> 00:09:50,040 and then to disappear from predators. 82 00:09:50,040 --> 00:09:55,520 This mirror may persuade him to reveal his solution to the problem. 83 00:09:55,520 --> 00:09:58,040 Now then, what do you think of that? 84 00:09:58,040 --> 00:10:01,000 Who's that? 85 00:10:01,000 --> 00:10:03,440 Yes, it's a rival. 86 00:10:06,800 --> 00:10:09,560 A tail wag. 87 00:10:09,560 --> 00:10:11,760 Yes! 88 00:10:13,160 --> 00:10:16,160 HE LAUGHS 89 00:10:16,160 --> 00:10:18,920 You're not going to get rid of me that way. 90 00:10:18,920 --> 00:10:21,440 Show us your signals. 91 00:10:21,440 --> 00:10:25,800 Well, press-up certainly is a keep-away challenge. 92 00:10:28,560 --> 00:10:30,600 And there, that's it! 93 00:10:32,400 --> 00:10:34,000 The full works. 94 00:10:38,160 --> 00:10:39,800 Ah, lovely! 95 00:10:41,320 --> 00:10:44,000 Once more. 96 00:10:44,000 --> 00:10:46,280 Thank you, and again. 97 00:10:48,560 --> 00:10:54,080 He obviously thinks that his position is being contested 98 00:10:54,080 --> 00:10:59,160 and he is displaying to show that he is as good as anyone else. 99 00:10:59,160 --> 00:11:01,560 So I guess I'll leave him in peace. 100 00:11:05,040 --> 00:11:08,560 An anole's throat flap appears for only a second or so, 101 00:11:08,560 --> 00:11:11,360 and then vanishes. 102 00:11:11,360 --> 00:11:13,880 And its owner, after sending his message, 103 00:11:13,880 --> 00:11:16,600 returns to camouflaged obscurity. 104 00:11:19,200 --> 00:11:22,440 Another family of lizards living in the tree-tops 105 00:11:22,440 --> 00:11:25,680 has an even more varied repertoire of signals. 106 00:11:25,680 --> 00:11:30,040 They use not only gestures, but body colours. 107 00:11:43,360 --> 00:11:45,840 They're chameleons. 108 00:11:49,600 --> 00:11:55,400 Their stronghold is the island of Madagascar. 109 00:11:55,400 --> 00:11:58,040 Here, there are over 60 different species of them, 110 00:11:58,040 --> 00:12:00,880 almost more than in the rest of the world put together. 111 00:12:02,800 --> 00:12:07,360 This is a panther chameleon 112 00:12:07,360 --> 00:12:10,360 and it's marvellously adapted 113 00:12:10,360 --> 00:12:12,360 for life among the branches. 114 00:12:14,560 --> 00:12:19,160 Its toes are divided into two bundles, three and two, 115 00:12:19,160 --> 00:12:25,280 and that means that it can use them just like forceps. 116 00:12:25,280 --> 00:12:29,680 Their grasping feet, supplemented by their gripping tail, 117 00:12:29,680 --> 00:12:34,000 enable them to become remarkable slow motion acrobats. 118 00:12:44,560 --> 00:12:49,000 I suppose chameleons are best known for their ability to change colour, 119 00:12:49,000 --> 00:12:51,800 and that does help in camouflage, 120 00:12:51,800 --> 00:12:55,320 but actually, they also use colour change 121 00:12:55,320 --> 00:13:00,360 as a way of communication and expressing their emotions. 122 00:13:06,120 --> 00:13:10,160 When a male panther chameleon spots a rival, 123 00:13:10,160 --> 00:13:14,320 he expresses his fury in glorious technicolour. 124 00:13:21,400 --> 00:13:25,800 Malawi, in central Africa, may not have as many species 125 00:13:25,800 --> 00:13:30,360 of chameleon as Madagascar, but it has one of the largest. 126 00:13:30,360 --> 00:13:32,400 Meller's chameleon, 127 00:13:32,400 --> 00:13:36,720 that can be 60 centimetres, nearly two feet, from nose to tail. 128 00:13:45,800 --> 00:13:48,840 Rival males, when they do battle, 129 00:13:48,840 --> 00:13:52,280 deploy a range of threats that is truly formidable. 130 00:14:47,320 --> 00:14:51,960 If signals don't deter, then they start to joust. 131 00:15:20,200 --> 00:15:22,800 It's not only males that fight. 132 00:15:22,800 --> 00:15:26,080 There are also battles between the sexes. 133 00:15:26,080 --> 00:15:30,880 This is the South African dwarf chameleon, a male in full courtship costume. 134 00:15:35,040 --> 00:15:39,760 This, somewhat less colourful, is a female. 135 00:15:45,720 --> 00:15:48,440 She is not welcoming his advances. 136 00:15:55,240 --> 00:15:59,600 As her mood darkens, so does her skin. 137 00:16:20,080 --> 00:16:22,880 She's driven him away, but why? 138 00:16:30,440 --> 00:16:33,920 There is a reason. 139 00:16:33,920 --> 00:16:35,880 She's pregnant. 140 00:16:35,880 --> 00:16:40,080 Her home, the South African Cape, can get quite cold, 141 00:16:40,080 --> 00:16:44,920 so instead of laying her eggs on the ground as most chameleons do, 142 00:16:44,920 --> 00:16:47,160 she retains them within her body 143 00:16:47,160 --> 00:16:52,440 and warms them by seeking out the sunniest places and sunbathing. 144 00:16:52,440 --> 00:16:56,720 Now they're ready to emerge, alive. 145 00:17:05,120 --> 00:17:09,600 Producing babies in the branches might seem to be a risky business, 146 00:17:09,600 --> 00:17:12,720 but the membrane enclosing each one will stick to a twig. 147 00:17:12,720 --> 00:17:15,960 If it hits one. 148 00:17:17,920 --> 00:17:21,480 And when at last the babies disentangle themselves, 149 00:17:21,480 --> 00:17:25,760 they immediately deploy their formidable chameleon grip. 150 00:18:19,720 --> 00:18:22,640 By the time they are properly dried out, 151 00:18:22,640 --> 00:18:27,040 the babies are as much at home in the branches as their mother. 152 00:18:51,240 --> 00:18:55,200 But for the most extraordinary chameleons of all, 153 00:18:55,200 --> 00:18:57,680 you have to look, not up in the trees, 154 00:18:57,680 --> 00:18:59,880 but down here on the leaf litter. 155 00:19:06,000 --> 00:19:09,120 A whole range of species live on the ground, 156 00:19:09,120 --> 00:19:12,720 many of which have only recently been discovered. 157 00:19:17,400 --> 00:19:22,600 This is surely the most extraordinary of all chameleons. 158 00:19:22,600 --> 00:19:28,160 It's the pygmy leaf chameleon. 159 00:19:28,160 --> 00:19:33,040 This is a male and he is fully grown, believe it or not. 160 00:19:33,040 --> 00:19:36,520 And yet, within this tiny little body, 161 00:19:36,520 --> 00:19:41,040 there are all the anatomical details of a normal-sized chameleon. 162 00:19:41,040 --> 00:19:43,920 What an extraordinary creature. 163 00:19:49,520 --> 00:19:54,160 Like all chameleons, it catches its food with its tongue. 164 00:19:56,600 --> 00:19:58,720 It eats tiny flies. 165 00:20:02,960 --> 00:20:08,440 Grasshoppers are popular with normal-sized chameleons. 166 00:20:29,160 --> 00:20:34,680 The tongue contains a tapered rod encircled by muscle. 167 00:20:34,680 --> 00:20:40,400 As the muscle contracts, the tongue shoots forward off the rod. 168 00:20:40,400 --> 00:20:44,120 The tip physically grasps the prey 169 00:20:44,120 --> 00:20:48,200 and then longitudinal muscles contract to pull the tongue 170 00:20:48,200 --> 00:20:51,200 back onto its rod, bringing the prey with it, 171 00:20:51,200 --> 00:20:54,240 which may weigh half as much as the chameleon itself. 172 00:21:05,320 --> 00:21:09,240 The whole action in reality is completed in a second or so. 173 00:21:21,280 --> 00:21:24,960 The canopy of a tropical forest is full of food, 174 00:21:24,960 --> 00:21:29,320 and lizards clamber around looking for it in many ways. 175 00:21:29,320 --> 00:21:31,920 Chameleons use their toes to grip the twigs, 176 00:21:31,920 --> 00:21:35,600 and geckos use theirs to stick to leaves, 177 00:21:35,600 --> 00:21:38,880 for their toes have adhesive pads on the ends. 178 00:21:40,400 --> 00:21:45,400 Most geckos feed on insects, but some take nectar from flowers, 179 00:21:45,400 --> 00:21:51,640 and a few collect liquid from insects in much the same way as we take milk from cows. 180 00:21:55,560 --> 00:22:00,360 The insect, a treehopper, is sitting head down drinking sap from the tree. 181 00:22:00,360 --> 00:22:03,680 It would be invisible were it not vibrating its abdomen. 182 00:22:05,200 --> 00:22:10,080 And that is what the gecko wants from it, a drop of honeydew. 183 00:22:10,080 --> 00:22:15,640 Honeydew is what remains of tree sap after the hopper has extracted the protein from it. 184 00:22:15,640 --> 00:22:19,920 It's very sweet and the gecko plainly loves it. 185 00:22:19,920 --> 00:22:23,440 Other less colourful species of gecko also drink honeydew, 186 00:22:23,440 --> 00:22:28,360 and some order it from the hopper by vibrating their heads. 187 00:22:40,240 --> 00:22:43,240 The hopper tells the gecko that a drink is on the way 188 00:22:43,240 --> 00:22:45,200 by waggling its abdomen. 189 00:22:57,240 --> 00:23:00,960 How the hopper benefits from this arrangement is not clear. 190 00:23:00,960 --> 00:23:05,240 Perhaps the gecko keeps predatory insects away 191 00:23:05,240 --> 00:23:07,920 and the honeydew is protection money. 192 00:23:09,440 --> 00:23:11,880 Most geckos are much less conspicuous, 193 00:23:11,880 --> 00:23:14,600 and are very difficult to see. 194 00:23:22,760 --> 00:23:26,800 It's the Madagascan leaf-tailed gecko. 195 00:23:26,800 --> 00:23:30,920 And its tail has wide flanges on either side 196 00:23:30,920 --> 00:23:33,680 so that it has become leaf shaped. 197 00:23:33,680 --> 00:23:36,120 But these aren't the only flanges. 198 00:23:36,120 --> 00:23:42,000 It has also got them all round its toes, its legs, and down its flank. 199 00:23:42,000 --> 00:23:46,920 And the consequence is that if it presses itself close to the bark 200 00:23:46,920 --> 00:23:53,160 and spreads those frills, it sheds no shadow at all. 201 00:23:53,160 --> 00:23:59,080 The irises of its eye are also part of this amazing camouflage. 202 00:23:59,080 --> 00:24:03,640 They have a kind of mottled, pale surface which makes them look 203 00:24:03,640 --> 00:24:09,000 exactly like one of these little blotches of lichen on the bark. 204 00:24:09,000 --> 00:24:13,920 All in all, it's a most extraordinary disguise. 205 00:24:15,440 --> 00:24:18,760 It, and indeed the majority of geckos, 206 00:24:18,760 --> 00:24:21,880 only really become active at night. 207 00:24:29,640 --> 00:24:33,680 Here in Bangkok, as in cities throughout the tropics, 208 00:24:33,680 --> 00:24:39,400 geckos have discovered that mankind's lights attract a great banquet of insects. 209 00:24:44,800 --> 00:24:50,880 As a result, almost every building has its own resident gecko population. 210 00:25:05,240 --> 00:25:10,640 Lizards, for the most part, are not known for being caring parents. 211 00:25:10,640 --> 00:25:12,880 But there are exceptions. 212 00:25:12,880 --> 00:25:15,760 It's spring in the woodlands of North America. 213 00:25:15,760 --> 00:25:18,200 An American robin is nesting, 214 00:25:18,200 --> 00:25:23,000 warming her eggs with the heat generated by her own body. 215 00:25:23,000 --> 00:25:27,720 And below on the forest floor, a five-lined skink 216 00:25:27,720 --> 00:25:31,480 is warming her cold-blooded body by basking in the sunshine, 217 00:25:31,480 --> 00:25:34,240 so that she can do the same thing. 218 00:25:41,880 --> 00:25:45,840 She has a nest below the log. 219 00:25:50,840 --> 00:25:55,040 It can get quite chilly in these woodlands, and she warms her eggs 220 00:25:55,040 --> 00:25:59,760 by transferring to them the heat that she's collected from the sun. 221 00:26:12,880 --> 00:26:17,760 She takes just as much care of her eggs as the robin does. 222 00:26:26,400 --> 00:26:29,440 A month later, and her eggs are hatching. 223 00:26:42,640 --> 00:26:45,160 The robin's eggs have hatched, too. 224 00:26:45,160 --> 00:26:50,240 Her nestlings are helpless, and need constant feeding. 225 00:26:50,240 --> 00:26:55,200 The young skinks, however, are already capable of finding food for themselves. 226 00:27:04,520 --> 00:27:07,160 Within a day or so, they've left their mother 227 00:27:07,160 --> 00:27:10,880 and are independently exploring the woodland floor for themselves. 228 00:27:18,880 --> 00:27:24,400 But there are other skinks whose family life lasts rather longer. 229 00:27:24,400 --> 00:27:28,960 These fields in South Australia are home to a little lizard 230 00:27:28,960 --> 00:27:34,080 that is so rare that it had been thought to be extinct for over 30 years 231 00:27:34,080 --> 00:27:37,640 until it was rediscovered in 1992. 232 00:27:37,640 --> 00:27:40,920 And the equipment you need to find it is, 233 00:27:40,920 --> 00:27:44,200 believe it or not, a fishing rod. 234 00:27:44,200 --> 00:27:47,280 Now let's see if I can tempt him out with this. 235 00:27:48,800 --> 00:27:52,280 Oh! Gosh. 236 00:27:52,280 --> 00:27:57,800 Now come up a little farther so we can see what you look like. 237 00:27:57,800 --> 00:28:02,120 That is a very rare little creature. 238 00:28:02,120 --> 00:28:05,840 It's a pygmy blue-tongued skink, 239 00:28:05,840 --> 00:28:11,480 and it lives in the holes that are made by trap-door spiders. 240 00:28:11,480 --> 00:28:15,680 And this one's clearly very hungry. 241 00:28:15,680 --> 00:28:19,120 Come on, won't you come out a little more? Come on. 242 00:28:19,120 --> 00:28:22,520 Just for us. Oh, ha-ha! 243 00:28:22,520 --> 00:28:24,320 It won. 244 00:28:27,400 --> 00:28:28,920 Let's have a closer look. 245 00:28:28,920 --> 00:28:32,480 I can do that with this optical probe 246 00:28:32,480 --> 00:28:36,240 with this viewing screen on the end. 247 00:28:36,240 --> 00:28:38,040 He's quite a long way down. 248 00:28:38,040 --> 00:28:40,200 There he is, 249 00:28:40,200 --> 00:28:42,680 all safe and snug. 250 00:28:42,680 --> 00:28:45,560 And he really is safe down here. 251 00:28:45,560 --> 00:28:51,160 Even a bushfire sweeping by wouldn't harm him, and of course 252 00:28:51,160 --> 00:28:55,640 this explains why no-one had seen these little lizards for so long. 253 00:28:55,640 --> 00:28:57,800 They're very difficult to find. 254 00:29:00,080 --> 00:29:06,560 But what's really special about this little lizard is its family life. 255 00:29:06,560 --> 00:29:10,760 Just look at these shots we got with that optical probe. 256 00:29:10,760 --> 00:29:13,960 That is a close-up of an adult's head, 257 00:29:13,960 --> 00:29:20,960 and there, just beside her head, is a tiny little head of a baby. 258 00:29:20,960 --> 00:29:24,080 That's one, and if we push past her, 259 00:29:24,080 --> 00:29:27,720 there's a baleful look of Mum, who doesn't appreciate this, 260 00:29:27,720 --> 00:29:32,200 and beyond, two. 261 00:29:32,200 --> 00:29:34,760 Two more babies. So that's three. 262 00:29:35,720 --> 00:29:39,720 Quite a crowded little home. 263 00:29:39,720 --> 00:29:43,880 So there they are, a nice little lizard family. 264 00:29:43,880 --> 00:29:49,680 And the babies will stay in that crowded hole for three weeks or so 265 00:29:49,680 --> 00:29:53,640 before they're ready to be able to go out into the outside world 266 00:29:53,640 --> 00:29:57,040 and look for a spider's burrow for themselves. 267 00:30:01,040 --> 00:30:06,960 There's another skink here whose family relations last for decades. 268 00:30:08,960 --> 00:30:12,360 This is a shingleback, 269 00:30:12,360 --> 00:30:15,840 or as it's called here in its home in Australia, 270 00:30:15,840 --> 00:30:17,960 a sleepy lizard. 271 00:30:17,960 --> 00:30:20,480 It's really quite a baffling creature because 272 00:30:20,480 --> 00:30:24,040 its head and the tail look very similar, 273 00:30:24,040 --> 00:30:25,880 maybe that confuses the predator. 274 00:30:25,880 --> 00:30:31,360 But if you get closer, it quickly shows which end is which, 275 00:30:31,360 --> 00:30:34,920 by threatening with this gape display. 276 00:30:34,920 --> 00:30:36,200 Ha-ha. 277 00:30:36,200 --> 00:30:39,040 Oh, you're very perky. 278 00:30:39,040 --> 00:30:42,240 And I have to be reasonably careful 279 00:30:42,240 --> 00:30:47,120 because it can bite, 280 00:30:47,120 --> 00:30:50,080 but at this time of the year, in the spring, 281 00:30:50,080 --> 00:30:56,320 it also has another, rather more gentle side to its character. 282 00:30:56,320 --> 00:30:59,000 There, I'll let you get on with it. 283 00:31:02,160 --> 00:31:05,480 A female catches the eye of a male. 284 00:31:17,440 --> 00:31:20,520 He starts to follow her wherever she goes. 285 00:31:28,120 --> 00:31:32,320 Couples stay side by side for up to two months. 286 00:31:46,920 --> 00:31:50,760 He courts her by gently nudging and licking her. 287 00:32:11,080 --> 00:32:13,760 Six months pass, 288 00:32:13,760 --> 00:32:19,640 and then eventually the results of this prolonged courtship begin to arrive. 289 00:32:24,280 --> 00:32:28,480 It's a long and strenuous business for a mother shingleback. 290 00:32:44,800 --> 00:32:50,600 She produces not a small egg, like the five-lined skink, 291 00:32:50,600 --> 00:32:52,160 but a live baby. 292 00:33:06,120 --> 00:33:07,640 It's a whopper. 293 00:33:31,760 --> 00:33:35,440 And there's another one to come. 294 00:33:35,440 --> 00:33:38,560 Together, the two weigh as much as a third of her bodyweight, 295 00:33:38,560 --> 00:33:42,960 the equivalent in human beings of carrying a three-year-old child. 296 00:33:49,640 --> 00:33:52,520 Like the Cape chameleon in South Africa, 297 00:33:52,520 --> 00:33:56,520 the female has been acting as a mobile incubator, 298 00:33:56,520 --> 00:34:00,760 seeking out the warmest spots she can find in order to bask. 299 00:34:01,640 --> 00:34:06,200 Producing such well-developed young is the shingleback's response 300 00:34:06,200 --> 00:34:09,840 to the fact that it can get quite cold in South Australia. 301 00:34:16,680 --> 00:34:20,360 Her young are so advanced that they soon leave her. 302 00:34:26,240 --> 00:34:30,520 But when spring returns, the same male and female 303 00:34:30,520 --> 00:34:34,760 will once again seek one another out and mate again. 304 00:34:34,760 --> 00:34:41,560 In fact, a pair will remain faithful to one another for as long as 20 years or more. 305 00:34:47,720 --> 00:34:53,000 The bond between them may even endure after death. 306 00:34:54,520 --> 00:34:57,720 They're slow-moving creatures and only too often, 307 00:34:57,720 --> 00:34:59,360 when crossing a road, 308 00:34:59,360 --> 00:35:03,840 they're unable to get out of the way of a passing car. 309 00:35:06,440 --> 00:35:08,240 If one of the pair is run over 310 00:35:08,240 --> 00:35:12,640 the other will often remain at its side for days, tenderly nudging it. 311 00:35:12,640 --> 00:35:16,920 You might even say that it was grieving. 312 00:35:22,000 --> 00:35:23,600 On the other side of the world, 313 00:35:23,600 --> 00:35:27,960 there are lizards with a very different lifestyle. 314 00:35:27,960 --> 00:35:33,080 They gather together in groups with densities higher than you can find anywhere else. 315 00:35:33,080 --> 00:35:35,680 And the reason they are able to do so, 316 00:35:35,680 --> 00:35:37,880 you can see alongside the waters of this, 317 00:35:37,880 --> 00:35:41,240 the Orange River in South Africa. 318 00:36:04,400 --> 00:36:09,640 The river is the breeding ground for vast swarms of black flies, 319 00:36:09,640 --> 00:36:13,240 excellent food for a lizard if it can catch them. 320 00:36:30,120 --> 00:36:33,080 In the early morning, the Augrabies flat lizards 321 00:36:33,080 --> 00:36:38,160 emerge from the cracks in the rocks where they've spent the night 322 00:36:38,160 --> 00:36:40,840 and bask in the sun to warm up. 323 00:36:44,520 --> 00:36:47,760 The males are the brightly coloured ones, 324 00:36:47,760 --> 00:36:52,160 as you can see from his marvellous blue head. 325 00:36:52,160 --> 00:36:56,880 But it's not his head that impresses his rivals so much, 326 00:36:56,880 --> 00:36:58,240 it's the underside, 327 00:36:58,240 --> 00:37:01,560 which, if he's a high status male, 328 00:37:01,560 --> 00:37:04,400 will be bright orange and yellow. 329 00:37:04,400 --> 00:37:06,440 And if another one turns up 330 00:37:06,440 --> 00:37:10,440 he will try and impress his rival by exposing that. 331 00:37:13,000 --> 00:37:15,320 These awkward looking postures 332 00:37:15,320 --> 00:37:18,440 reveal why these creatures are called flat lizards. 333 00:37:20,880 --> 00:37:23,960 By regularly displaying their vivid badges, 334 00:37:23,960 --> 00:37:25,920 the males repeatedly confirm 335 00:37:25,920 --> 00:37:30,080 their place in the pecking order, and so keep fighting to a minimum. 336 00:37:34,480 --> 00:37:37,720 As a female moves from one territory to another, 337 00:37:37,720 --> 00:37:40,520 so each male courts her in turn. 338 00:37:51,040 --> 00:37:55,000 And now they're really warmed up and active, 339 00:37:55,000 --> 00:37:59,280 and whole groups of them begin to travel down across the rocks 340 00:37:59,280 --> 00:38:02,360 towards the river where they'll find their food. 341 00:38:08,520 --> 00:38:12,240 But down here, where the flies swarm, it's a free for all. 342 00:38:12,240 --> 00:38:14,440 And that causes a lot of trouble. 343 00:38:16,920 --> 00:38:21,240 Catching flies is necessarily an acrobatic business. 344 00:38:30,840 --> 00:38:34,320 But you can't leap for flies and still keep properly spaced out. 345 00:38:34,320 --> 00:38:39,200 So there are inevitably quarrels between rival males. 346 00:38:47,480 --> 00:38:51,320 Females, on the other hand, are only interested in getting a good meal. 347 00:38:53,240 --> 00:38:56,040 Fired-up males, however, have other ideas. 348 00:38:57,560 --> 00:39:00,880 For them, there is more to life than just dinner. 349 00:39:12,880 --> 00:39:15,120 And some won't take no for an answer. 350 00:39:28,440 --> 00:39:30,120 The females want food. 351 00:39:36,680 --> 00:39:38,680 They need a square meal 352 00:39:38,680 --> 00:39:41,560 to nourish the eggs that are developing within them. 353 00:39:48,200 --> 00:39:51,680 But they won't get any peace until they leave the restaurant 354 00:39:51,680 --> 00:39:54,800 and get back home, where life is better regulated. 355 00:39:57,040 --> 00:40:00,120 The high-octane social life of the flat lizards, 356 00:40:00,120 --> 00:40:04,000 with its constant squabbling, seems to be very stressful. 357 00:40:04,000 --> 00:40:05,880 But for other lizards, 358 00:40:05,880 --> 00:40:10,760 fighting is less frequent but altogether more impressive. 359 00:40:31,880 --> 00:40:34,880 A Mexican beaded lizard. 360 00:40:34,880 --> 00:40:38,320 One of the few lizards in the world with a poisonous bite. 361 00:40:38,320 --> 00:40:41,440 And a very virulent one it is, too. 362 00:40:42,960 --> 00:40:46,280 In the spring, rival males fight, 363 00:40:46,280 --> 00:40:48,760 according to a very specific set of rules. 364 00:40:56,000 --> 00:40:58,680 They use neither their sharp, powerful claws, 365 00:40:58,680 --> 00:41:02,120 nor their poisonous bite in their battles. 366 00:41:20,640 --> 00:41:25,360 At first they grapple rather warily, to assess each other's strength. 367 00:41:34,640 --> 00:41:37,000 Then they begin to wrestle in earnest, 368 00:41:37,000 --> 00:41:39,920 each trying to pin down the other on the ground. 369 00:41:54,080 --> 00:41:56,520 These two are evenly matched. 370 00:41:56,520 --> 00:41:58,560 Neither can get the crucial throw. 371 00:41:58,560 --> 00:42:01,080 It's rather like an arm-wrestling contest, 372 00:42:01,080 --> 00:42:04,000 and the bout can continue for several hours. 373 00:42:41,560 --> 00:42:46,000 The eventual winner is the one who ends up on top most frequently. 374 00:42:46,000 --> 00:42:49,960 It's a controlled test of strength in which, 375 00:42:49,960 --> 00:42:53,880 despite their lethal weaponry, no-one gets seriously hurt. 376 00:42:57,240 --> 00:42:59,400 Other lizards defend themselves, 377 00:42:59,400 --> 00:43:03,440 not with physical strength, but by deceit. 378 00:43:04,960 --> 00:43:06,480 The South African desert. 379 00:43:08,080 --> 00:43:09,600 A bushveld lizard. 380 00:43:13,960 --> 00:43:15,120 This is another. 381 00:43:15,120 --> 00:43:19,120 It looks very different, but that is because it's a baby. 382 00:43:21,680 --> 00:43:23,840 It not only has different colouration, 383 00:43:23,840 --> 00:43:28,120 it also walks in a very different and quite extraordinary way. 384 00:43:38,120 --> 00:43:39,880 It appears to be imitating 385 00:43:39,880 --> 00:43:41,480 one of the local beetles, 386 00:43:41,480 --> 00:43:42,560 that one. 387 00:43:42,560 --> 00:43:44,000 And to discover why, 388 00:43:44,000 --> 00:43:48,080 I'm going to take defensive measures with these goggles. 389 00:43:50,080 --> 00:43:55,240 This beetle is known as an oogpister - an eye-spitter. 390 00:43:55,240 --> 00:43:58,560 And that is because it's squirting formic acid at me. 391 00:43:58,560 --> 00:44:04,480 Yeah, and if any of that got into my eye it would be extremely painful. 392 00:44:04,480 --> 00:44:05,840 It's a defensive system, 393 00:44:05,840 --> 00:44:08,360 and the lizards are benefiting 394 00:44:08,360 --> 00:44:12,320 by imitating a beetle with that kind of armoury. 395 00:44:14,760 --> 00:44:17,680 A young lizard closely matches the beetle, 396 00:44:17,680 --> 00:44:20,400 both in its appearance and its walk. 397 00:44:20,400 --> 00:44:22,760 So birds that prey on lizards 398 00:44:22,760 --> 00:44:26,400 assume it has a nasty spray, and leave it alone. 399 00:44:35,160 --> 00:44:38,880 Lizards can cope with dry, hot conditions so well 400 00:44:38,880 --> 00:44:42,240 they dominate the fauna in tropical deserts around the world, 401 00:44:42,240 --> 00:44:45,240 including those in central Australia. 402 00:44:49,800 --> 00:44:54,480 Their tough, scaly skins prevent their bodies from losing moisture, 403 00:44:54,480 --> 00:44:56,360 so that they can flourish in these 404 00:44:56,360 --> 00:44:59,600 arid, baking hot lands that other animals find so testing. 405 00:45:09,040 --> 00:45:13,400 Some wear the most elaborate suits of armour. 406 00:45:21,640 --> 00:45:27,240 This is surely the most enchanting of lizards. 407 00:45:27,240 --> 00:45:32,640 It's called the thorny devil or Moloch, 408 00:45:32,640 --> 00:45:37,160 after Moloch, the god in the Bible who ate little children. 409 00:45:37,160 --> 00:45:39,800 Both names surely are a slander 410 00:45:39,800 --> 00:45:41,680 on such an engaging little animal. 411 00:45:41,680 --> 00:45:45,520 It feeds entirely on ants, 412 00:45:45,520 --> 00:45:47,240 and, as you can see, 413 00:45:47,240 --> 00:45:50,600 there's not much of a meal in any one of them. 414 00:45:50,600 --> 00:45:55,120 But the good thing about ants as far as Moloch is concerned, 415 00:45:55,120 --> 00:45:58,360 is that there's always some around. 416 00:45:58,360 --> 00:46:00,840 And this little creature 417 00:46:00,840 --> 00:46:03,720 will sit by an ant trail patiently, 418 00:46:05,920 --> 00:46:07,880 for hours on end, 419 00:46:07,880 --> 00:46:11,080 simply picking off one ant at a time. 420 00:46:13,880 --> 00:46:16,600 The Australian desert is also home 421 00:46:16,600 --> 00:46:20,640 to one of the most powerful of the family. 422 00:46:20,640 --> 00:46:24,520 Monitors are the kings of lizards, 423 00:46:24,520 --> 00:46:27,480 and this is the perentie, 424 00:46:27,480 --> 00:46:32,960 the biggest species of monitor in Australia. 425 00:46:32,960 --> 00:46:37,880 It can grow up to two metres long, six feet. 426 00:46:37,880 --> 00:46:41,200 And it's a highly intelligent animal. 427 00:46:41,200 --> 00:46:46,560 It's got very acute senses of sight and hearing and taste and smell, 428 00:46:46,560 --> 00:46:52,720 and, like all monitors, it can do something no other lizard can do. 429 00:46:52,720 --> 00:46:56,600 It can run continuously for a very long time. 430 00:46:56,600 --> 00:47:01,040 And that enables it to become an endurance hunter, 431 00:47:01,040 --> 00:47:02,800 chasing down its prey. 432 00:47:08,600 --> 00:47:13,680 Most lizards inflate their lungs using the same muscles they use for walking, 433 00:47:13,680 --> 00:47:18,680 so they can't run and breathe effectively at the same time. 434 00:47:24,360 --> 00:47:27,000 But monitors have big muscular throats 435 00:47:27,000 --> 00:47:30,040 which they use like bellows to pump air 436 00:47:30,040 --> 00:47:31,400 into their lungs. 437 00:47:31,400 --> 00:47:35,160 And they can do that even when they're running. 438 00:47:41,080 --> 00:47:43,240 This special way of breathing 439 00:47:43,240 --> 00:47:47,520 enables them to reach speeds of over 20 miles an hour. 440 00:47:47,520 --> 00:47:50,560 Over distance, they are one of the fastest of all reptiles. 441 00:47:52,720 --> 00:47:57,680 The cold-blooded perentie can even out-run a warm-blooded rabbit. 442 00:48:02,120 --> 00:48:04,800 So, the lizards have colonised the world. 443 00:48:04,800 --> 00:48:08,680 From swamps to rainforests, from woodland to desert. 444 00:48:08,680 --> 00:48:13,920 And in doing so, they reveal such a variety of form and behaviour 445 00:48:13,920 --> 00:48:18,280 that they truly can be called the dragons of the dry. 446 00:48:28,680 --> 00:48:33,880 Much of our filming for this programme was done in Australia. 447 00:48:33,880 --> 00:48:36,000 There, there are lizards everywhere. 448 00:48:36,000 --> 00:48:39,960 Just walk around in the bush and you'll see them. 449 00:48:39,960 --> 00:48:43,400 But usually you won't get much more than a brief glimpse. 450 00:48:47,840 --> 00:48:51,840 To film their intimate behaviour, we needed help from experts. 451 00:48:55,640 --> 00:48:59,080 We travelled to Australia to meet an expert called Mike Bull. 452 00:48:59,080 --> 00:49:03,720 He knows Australian lizards as well as anyone. 453 00:49:03,720 --> 00:49:08,440 He and his team study many species in one small area north of Adelaide, 454 00:49:08,440 --> 00:49:11,560 using all manner of gadgets and gizmos, 455 00:49:11,560 --> 00:49:14,640 to investigate every part of their lives. 456 00:49:22,440 --> 00:49:24,960 We are particularly interested in the lizards 457 00:49:24,960 --> 00:49:29,440 that Mike understands best of all, the shingleback or sleepy lizard. 458 00:49:29,440 --> 00:49:32,960 He knows 10,000 of them individually. 459 00:49:36,520 --> 00:49:40,240 On the face of it, the sleepy lizard doesn't seem to do a lot, 460 00:49:40,240 --> 00:49:42,520 but Mike knows so much about them 461 00:49:42,520 --> 00:49:46,080 that we were able to make them one of the stars of our film. 462 00:49:46,080 --> 00:49:49,320 He's discovered that they're the only lizards in the world 463 00:49:49,320 --> 00:49:53,200 that remain faithful to one partner for all their lives. 464 00:49:53,200 --> 00:49:56,240 But that wasn't the reason that he began to study them. 465 00:49:56,240 --> 00:50:00,240 Tell me first how you first saw sleepy lizards 466 00:50:00,240 --> 00:50:01,920 and what attracted you to them. 467 00:50:01,920 --> 00:50:05,600 I started because I was interested in parasites that live on the lizard. 468 00:50:05,600 --> 00:50:08,080 To find the parasites I had to look at the lizards 469 00:50:08,080 --> 00:50:11,320 and discovered they were more interesting than the parasites. 470 00:50:11,320 --> 00:50:14,680 I think they're one of the most handsome animals you'll ever find. 471 00:50:14,680 --> 00:50:17,760 The other thing is it's probably the only animal that 472 00:50:17,760 --> 00:50:22,840 you know if you're driving in a car and see one 100 metres down the road, you know you've caught it, 473 00:50:22,840 --> 00:50:27,080 and it's also one that I think I'm going to be sufficiently agile 474 00:50:27,080 --> 00:50:30,400 to keep on catching until I'm well past 80! 475 00:50:30,400 --> 00:50:34,640 And even I, I think could scrag a sleepy lizard. 476 00:50:34,640 --> 00:50:37,600 I'll see whether I can manage it. 477 00:50:37,600 --> 00:50:42,280 Sleepy lizards like to bask on warm roads, so they're easy to find, 478 00:50:42,280 --> 00:50:45,320 and they move so slowly they're easy to pick up. 479 00:50:45,320 --> 00:50:49,240 So the team were able to weigh and measure a whole population, 480 00:50:49,240 --> 00:50:52,280 and thus discovered that pairs remained together in a way 481 00:50:52,280 --> 00:50:56,000 that was previously known only in birds and mammals. 482 00:50:56,000 --> 00:50:58,920 But that was just the start. 483 00:50:58,920 --> 00:51:00,760 Next, they turned to technology, 484 00:51:00,760 --> 00:51:05,440 some of it advanced, some a little bizarre. 485 00:51:05,440 --> 00:51:10,160 They used remotely-controlled rubber sleepy lizards 486 00:51:10,160 --> 00:51:12,640 to test how lizards reacted to one another. 487 00:51:14,200 --> 00:51:16,440 In this case, not very much. 488 00:51:20,520 --> 00:51:23,400 Mike's team suspected that another lizard in the area, 489 00:51:23,400 --> 00:51:27,840 the gidgee skink, had an even more complex social life, 490 00:51:27,840 --> 00:51:30,760 but this was difficult to prove because when approached 491 00:51:30,760 --> 00:51:36,160 the skinks wedged themselves in cracks in the rocks, making it impossible to identify who's who. 492 00:51:37,680 --> 00:51:41,280 The solution was to microchip each lizard 493 00:51:41,280 --> 00:51:45,760 so it could then be scanned just like your supermarket shopping, 494 00:51:45,760 --> 00:51:48,800 with a barcode reader on the end of a pole. 495 00:51:51,400 --> 00:51:53,760 This clever use of technology 496 00:51:53,760 --> 00:51:57,280 revealed what looked like a jumble of lizards on a pile of rocks, 497 00:51:57,280 --> 00:52:00,200 to be actually a little lizard family, with young 498 00:52:00,200 --> 00:52:02,440 that stay with their parents for life. 499 00:52:04,920 --> 00:52:10,480 I'm sure that there are going to be many other complex social organisations 500 00:52:10,480 --> 00:52:14,960 that will be uncovered in those species if we just simply take the time to look at them. 501 00:52:14,960 --> 00:52:18,360 But it's just the time and the patience to watch them, 502 00:52:18,360 --> 00:52:21,600 and watching a lizard is very unrewarding 503 00:52:21,600 --> 00:52:26,880 because they will come out and bask, sit by a bush, 504 00:52:26,880 --> 00:52:32,120 and if they see you're there, they'll decide they're not going to do very much for the rest of the day. 505 00:52:33,000 --> 00:52:37,080 To find out just what sleepy lizards get up to when no-one's around, 506 00:52:37,080 --> 00:52:42,200 Mike's team use a rather bizarre device they call a "waddleometer". 507 00:52:42,200 --> 00:52:46,480 It may look a little odd, but it records a lizard's GPS co-ordinates, 508 00:52:46,480 --> 00:52:50,840 counts its steps and even notes whether it's in sun or shade, 509 00:52:50,840 --> 00:52:54,560 all without troubling the lizard and without anyone having to be there. 510 00:52:54,560 --> 00:52:58,400 So you think there's probably the secret world of the lizard 511 00:52:58,400 --> 00:53:00,680 which no human being has ever seen, 512 00:53:00,680 --> 00:53:04,480 because if a human being is there the lizard won't behave that way? 513 00:53:04,480 --> 00:53:08,040 I'm sure that's part of it. It's the uncertainty principle, 514 00:53:08,040 --> 00:53:12,200 the closer you get to watch something the less normally it's behaving. 515 00:53:12,200 --> 00:53:16,280 And so it's only by getting these remote and new technologies 516 00:53:16,280 --> 00:53:19,720 that allow us to really get into the secret world of the lizards, 517 00:53:19,720 --> 00:53:22,680 that we can find these amazing things that they're doing. 518 00:53:22,680 --> 00:53:23,760 How extraordinary. 519 00:53:25,280 --> 00:53:29,880 One of their latest techniques uses miniature cameras which they use to study 520 00:53:29,880 --> 00:53:34,280 a very special lizard that we were also particularly keen to film. 521 00:53:39,600 --> 00:53:42,880 It's so rare that it was thought to be extinct for over 30 years, 522 00:53:42,880 --> 00:53:45,720 until it was thrust back into the public eye 523 00:53:45,720 --> 00:53:49,520 when it was discovered in some very unusual circumstances. 524 00:53:51,280 --> 00:53:54,920 A group of biologists were doing a standard biological survey. 525 00:53:54,920 --> 00:54:00,640 They were just coming back to town to pick up supplies and just on the road they saw a dead brown snake. 526 00:54:00,640 --> 00:54:04,680 Most people wouldn't even look at it as they're so common around here, 527 00:54:04,680 --> 00:54:06,680 but these were dedicated biologists. 528 00:54:06,680 --> 00:54:08,920 They had a look, noticed there was a bulge, 529 00:54:08,920 --> 00:54:11,440 so they thought, "Let's see what it's been eating." 530 00:54:11,440 --> 00:54:18,920 Opened it up and there was this lizard that no-one had seen for 30 years, the pygmy blue-tongued lizard. 531 00:54:18,920 --> 00:54:23,160 How lovely, though I dare say it wasn't all that lovely when they actually saw it. 532 00:54:24,120 --> 00:54:26,800 Miniature cameras have produced images 533 00:54:26,800 --> 00:54:33,240 that are slowly helping to build up a comprehensive picture of the life of these rare little creatures. 534 00:54:35,440 --> 00:54:37,560 Their burrows are more than just homes. 535 00:54:37,560 --> 00:54:43,200 They're also hiding places where they can wait in ambush for spiders and crickets. 536 00:54:43,200 --> 00:54:45,920 But they don't seem too keen on ants. 537 00:54:47,960 --> 00:54:50,880 They also serve as bolt holes when danger approaches. 538 00:54:56,960 --> 00:54:58,320 Despite all this work, 539 00:54:58,320 --> 00:55:01,680 Mike's team had never recorded their life underground. 540 00:55:01,680 --> 00:55:05,160 So we were able to help with a little of our own technology 541 00:55:05,160 --> 00:55:09,320 and record the first ever pictures of a pygmy blue-tongue family. 542 00:55:09,320 --> 00:55:13,200 Three babies alongside their mother in their little hole. 543 00:55:19,080 --> 00:55:22,240 But all this technology, ingenious though it is, 544 00:55:22,240 --> 00:55:25,680 is no substitute for years of dedicated observation. 545 00:55:25,680 --> 00:55:29,840 Mike's approach of simply driving for miles across the Australian outback 546 00:55:29,840 --> 00:55:35,080 is very fruitful, and you see lots of other things as well as lizards. 547 00:55:35,080 --> 00:55:40,160 Up here is just a wonderful place for lizards and kangaroos. 548 00:55:40,160 --> 00:55:43,520 Ha, boy! Eastern grey, beautiful. 549 00:55:43,520 --> 00:55:46,040 Now, you won't catch a lizard doing that. 550 00:55:53,880 --> 00:55:56,080 Oh, look, there's a pair just down there. 551 00:56:03,800 --> 00:56:08,160 It turned out that Mike had spotted two old friends. 552 00:56:13,120 --> 00:56:15,720 This is the male and the female. 553 00:56:15,720 --> 00:56:19,040 This is 1172 and 3345, 554 00:56:19,040 --> 00:56:22,120 - I think they've been together for about ten years. - Really? 555 00:56:22,120 --> 00:56:25,680 We've got some other pairs that have been together for over 20 years. 556 00:56:25,680 --> 00:56:27,920 They stay together during the springtime 557 00:56:27,920 --> 00:56:31,120 and mate towards the end of the spring and then they separate, 558 00:56:31,120 --> 00:56:33,160 but the next year the same two lizards, 559 00:56:33,160 --> 00:56:37,680 we'll find them back together again, usually in the same place along this road. 560 00:56:37,680 --> 00:56:40,000 Aren't they terrific? 561 00:56:40,000 --> 00:56:43,200 They use their tongues to pick up chemical signals 562 00:56:43,200 --> 00:56:46,760 and you can see they're actually sensing each other at the moment. 563 00:56:46,760 --> 00:56:49,440 I think that's really very touching. 564 00:56:51,840 --> 00:56:53,600 I'd say that's a risky business. 565 00:56:54,720 --> 00:56:59,200 With obsessive dedication and ever-advancing technology, 566 00:56:59,200 --> 00:57:02,200 who knows what Mike and his team will uncover 567 00:57:02,200 --> 00:57:05,640 about the secret lives of sleepy lizards?