1 00:01:07,900 --> 00:01:12,400 These beautiful flowers belong to one of the most successful, 2 00:01:12,730 --> 00:01:15,650 the most widespread and the commonest of plants. 3 00:01:19,780 --> 00:01:23,410 There are about 10,000 species in this one family, 4 00:01:23,700 --> 00:01:28,040 and they claim over a quarter of all the vegetated land on earth. 5 00:01:28,420 --> 00:01:32,880 They are pollinated by the wind, they need far less water than most trees, 6 00:01:33,130 --> 00:01:38,640 and they can survive both burning and freezing. They are the grasses. 7 00:01:46,600 --> 00:01:51,020 These tough, persistent plants continue to grow even when they're trimmed 8 00:01:51,190 --> 00:01:54,440 day after day by grazing teeth. 9 00:01:55,900 --> 00:01:58,200 They are able to withstand all this rough treatment 10 00:01:58,360 --> 00:02:01,990 because the point from which a grass leaf grows is at its base 11 00:02:02,200 --> 00:02:05,160 close to the ground and is permanently active. 12 00:02:05,450 --> 00:02:11,460 So grass provides a continuous banquet for creatures big and small. 13 00:02:17,800 --> 00:02:22,470 Down among the tangled grass stems live not only creatures that eat grass 14 00:02:22,760 --> 00:02:25,930 but others that feed on the grass-eaters. 15 00:02:26,930 --> 00:02:32,650 Lizards snap up small insects and mantis munch grasshoppers. 16 00:02:44,450 --> 00:02:47,540 Spiders tackle almost any creature that moves 17 00:02:47,700 --> 00:02:51,250 and dung beetles clear up the droppings from above. 18 00:02:52,580 --> 00:02:57,010 Among the most industrious of these tiny labourers are the termites. 19 00:02:57,300 --> 00:03:02,140 On many tropical grasslands, they flourish in such numbers that, one way or another, 20 00:03:02,340 --> 00:03:08,060 they consume more of the grass than big creatures like antelope, cows or kangaroo. 21 00:03:12,600 --> 00:03:18,190 In Brazil's savannahs, there are more termite mounds per acre than anywhere in the world. 22 00:03:18,440 --> 00:03:20,400 And termites are highly nutritious - 23 00:03:20,700 --> 00:03:27,660 so much so that the giant anteater can exist by feeding on them and nothing else whatever. 24 00:03:32,750 --> 00:03:38,130 This creature has very poor eyesight and very poor hearing, 25 00:03:38,760 --> 00:03:44,930 and finds its way around mostly by smell, so, as long as I keep downwind of it, 26 00:03:45,140 --> 00:03:50,060 there's no reason why it should be particularly disturbed by my presence. 27 00:03:50,810 --> 00:03:54,060 You might think that that would make it very vulnerable to enemies. 28 00:03:54,400 --> 00:03:58,690 The fact is, out on the savannahs here, it's got very few enemies. 29 00:03:58,900 --> 00:04:05,820 The only things that might attack it are a jaguar or a puma, or if it was a baby, a savannah fox. 30 00:04:06,120 --> 00:04:10,160 And it has a very good defence against such creatures. 31 00:04:10,540 --> 00:04:16,840 Those huge forelegs, with enormous muscles on them and gigantic claws, 32 00:04:17,170 --> 00:04:23,510 are quite powerful enough to rip the stomach from a puma or a jaguar. 33 00:04:24,340 --> 00:04:30,640 It was always thought that those legs are actually for ripping open termite hills, 34 00:04:30,890 --> 00:04:34,600 and they may be used to some extent for that purpose. 35 00:04:34,810 --> 00:04:39,110 But it seems more likely now that they are primarily defensive weapons, 36 00:04:39,270 --> 00:04:41,360 because when they actually come to feed, 37 00:04:41,530 --> 00:04:45,240 this creature doesn't do so much of a sweep with its front claws 38 00:04:45,410 --> 00:04:52,080 as to use them very, very carefully to open the exit tunnels in the termite hills. 39 00:04:53,500 --> 00:04:57,040 Once it has done that, it pokes its nose into the tunnel entrance 40 00:04:57,250 --> 00:05:01,210 and flicks out its 20-inch-long tongue, coated with sticky mucus, 41 00:05:01,380 --> 00:05:05,590 and picks off the worker termites clinging to the tunnel walls. 42 00:05:12,600 --> 00:05:16,640 After about half a minute, before the soldier termites - which have powerful bites - 43 00:05:16,850 --> 00:05:21,400 can rally to the defence of the opened tunnel, the anteater moves on. 44 00:05:22,650 --> 00:05:26,820 It is a wanderer, always on the move, sleeping at night out in the open, 45 00:05:27,110 --> 00:05:31,030 blanketed against the cold by its huge hairy tail. 46 00:05:37,040 --> 00:05:42,130 Having no permanent den, the female carries her youngster with her, piggyback. 47 00:06:00,400 --> 00:06:03,980 Other termite hunters live on the surface of the mounds themselves. 48 00:06:04,280 --> 00:06:09,160 Beetle larvae lurk in burrows and lure flying ants and other insects to them 49 00:06:09,320 --> 00:06:11,910 by the luminous glow of their heads. 50 00:06:39,560 --> 00:06:44,150 Sometimes the termite mounds are attacked at their very foundations. 51 00:06:44,650 --> 00:06:48,240 This is the biggest insect-eater on earth, the giant armadillo, 52 00:06:48,450 --> 00:06:51,240 a massive animal that weighs over a hundredweight. 53 00:06:51,660 --> 00:06:53,320 There are few more powerful diggers. 54 00:06:53,700 --> 00:06:56,580 It's no finicky eater like the giant anteater, 55 00:06:56,750 --> 00:07:00,420 but rips its way through the ground into the heart of the termite hill. 56 00:07:04,960 --> 00:07:08,550 With its defences breached, the termite colony is very vulnerable. 57 00:07:08,970 --> 00:07:13,140 This mouse, oxymicterus, has a particular fondness for termites 58 00:07:13,300 --> 00:07:16,470 and regularly follows in the wake of the giant armadillo. 59 00:07:19,480 --> 00:07:22,350 But the termites' biggest enemies are even smaller. 60 00:07:23,480 --> 00:07:29,530 Carnivorous ants regularly raid the colonies, carrying off the helpless, pallid termite larvae. 61 00:07:31,240 --> 00:07:35,450 The defenders of the colony, the soldier termites, engage the enemy ants. 62 00:07:42,170 --> 00:07:45,460 These termite warriors have jaws so specialised for fighting 63 00:07:45,670 --> 00:07:49,760 that they can't feed for themselves and have to be tended by the workers. 64 00:07:51,050 --> 00:07:53,510 Each species is armed in its own way. 65 00:07:56,930 --> 00:08:00,140 Some have short nippers, some sharp shears. 66 00:08:00,390 --> 00:08:05,400 Others have blades that strike outwards and others nozzles on their forehead 67 00:08:05,560 --> 00:08:08,900 through which they squirt a sticky poison spray. 68 00:08:27,960 --> 00:08:30,880 Other ants are vegetarians, like the termites, 69 00:08:31,210 --> 00:08:36,260 and use their jaws to demolish the living grass plants, scissoring up the leaves, 70 00:08:36,470 --> 00:08:40,100 sawing through the stems and carrying off the plant piecemeal. 71 00:08:44,560 --> 00:08:50,110 Grass consists largely of cellulose and that is a very difficult substance to digest. 72 00:08:50,360 --> 00:08:53,820 Termites do it with the help of bacteria in their gut. 73 00:08:54,320 --> 00:08:57,870 The grass-cutting ants have another and quite extraordinary method 74 00:08:58,070 --> 00:09:00,620 of making its nutriment digestible. 75 00:09:01,120 --> 00:09:04,210 Laboriously, they haul the pieces of grass back to their nest, 76 00:09:04,410 --> 00:09:09,500 which may be as much as 100 yards away and have several hundred small entrances. 77 00:09:12,170 --> 00:09:17,140 Inside an entrance, a tunnel leads down into a vast labyrinth of corridors 78 00:09:17,300 --> 00:09:21,560 that may extend for 80 or 90 feet in a horizontal direction 79 00:09:21,720 --> 00:09:25,940 and lead to as many as 2,000 interlinked chambers. 80 00:09:30,150 --> 00:09:34,860 Such a nest may contain as many as 20 million ants. 81 00:09:43,620 --> 00:09:47,670 The workers carry their cuttings deeper and deeper into the nest. 82 00:09:51,920 --> 00:09:57,050 And here, 15 feet below the surface of the ground, in special chambers, 83 00:09:57,340 --> 00:10:00,720 they feed the grass to a fungus. 84 00:10:01,600 --> 00:10:07,940 This fungus forms crumbly white lumps and grows nowhere else but in these nests. 85 00:10:10,480 --> 00:10:13,730 Carefully, the ant gardeners clean every fragment of grass. 86 00:10:13,940 --> 00:10:17,610 Meticulously, they remove every spore of any other fungus 87 00:10:17,820 --> 00:10:22,330 that might grow down here if it got the chance. Weeds, as you might say. 88 00:10:22,870 --> 00:10:26,120 The waxy skin that covers the leaf surface is stripped away 89 00:10:26,290 --> 00:10:30,250 and then the pieces are cut up into even smaller fragments. 90 00:10:36,510 --> 00:10:41,390 The gardeners push the prepared morsels of grass into the mass of the fungus. 91 00:10:41,680 --> 00:10:45,680 The fungus digests it, cellulose and all, and grows, 92 00:10:45,850 --> 00:10:51,650 and the ants then feed on the fungus, which, unlike grass, they can digest. 93 00:11:03,490 --> 00:11:06,330 The ants tend their gardens with great care. 94 00:11:06,660 --> 00:11:10,500 Dead pieces of fungus and coarse, unsuitable fragments of leaves 95 00:11:10,710 --> 00:11:13,750 are carefully removed and carried away. 96 00:11:20,510 --> 00:11:26,810 With unflagging energy, porter lines of ants carry the waste down the long corridors 97 00:11:26,970 --> 00:11:34,110 to the lowest chambers of all, 20 feet below ground, that serve as the colony's refuse tips. 98 00:11:46,580 --> 00:11:50,540 These are not only rubbish dumps, but cemeteries, 99 00:11:50,750 --> 00:11:54,880 for here they also bring the bodies of dead workers. 100 00:12:07,640 --> 00:12:12,310 Dawn on the grasslands of Brazil, the campo. 101 00:12:26,070 --> 00:12:29,160 It's still chilly and the dew lies heavily. 102 00:12:29,490 --> 00:12:35,170 But the rising sun will soon dry out the pasturage and rouse the daytime inhabitants. 103 00:13:02,530 --> 00:13:09,280 The grassland birds have no trees from which to sing. Some make do with grass stems. 104 00:13:09,950 --> 00:13:15,960 Others, like the scissor-tailed flycatcher, proclaim their territorial rights by visual display 105 00:13:16,170 --> 00:13:20,750 flying incessantly and conspicuously above their chosen plots. 106 00:13:37,270 --> 00:13:44,400 The seriama, a catcher of snakes and insects, surveys the prospects from a termite hill. 107 00:13:45,950 --> 00:13:49,620 The tapir has browsed throughout the night, but now, as the sun rises, 108 00:13:49,780 --> 00:13:54,290 it makes its way back to the forest that grows in the moist ground beside the river, 109 00:13:54,450 --> 00:14:01,420 for it prefers that shady obscurity to the hot conspicuousness of the daytime plains. 110 00:14:07,550 --> 00:14:13,220 On the other hand, the savannah deer has slept all night and only grazes when it is light. 111 00:14:13,720 --> 00:14:16,100 It prefers to be able to see its enemies. 112 00:14:18,940 --> 00:14:24,280 The armadillo is no grass-eater. It's looking for insects, roots and birds' eggs, 113 00:14:24,480 --> 00:14:26,900 and even a lizard or a small snake. 114 00:14:32,910 --> 00:14:36,870 As the day warms up, reptiles become active. 115 00:14:40,880 --> 00:14:45,760 The tegu lizard is sufficiently powerful to be able to take on all-comers. 116 00:14:47,090 --> 00:14:54,180 Just what it likes, and no small bird, no matter how aggressive, is able to repel a hungry tegu. 117 00:15:08,650 --> 00:15:11,950 Eggs on the ground are very much at risk from creatures like this. 118 00:15:12,160 --> 00:15:16,080 But where else can you put them? There are few trees on the grassland. 119 00:15:16,620 --> 00:15:18,830 But there are termite hills. 120 00:15:23,670 --> 00:15:27,170 The flicker is a kind of woodpecker and drills into termite hills 121 00:15:27,340 --> 00:15:30,930 just as efficiently as its cousins do into tree trunks. 122 00:15:33,600 --> 00:15:38,180 And when the flicker has finished with its hole, kestrels often take it over. 123 00:15:44,560 --> 00:15:46,110 The male has a lizard. 124 00:15:46,360 --> 00:15:50,990 Softly, he summons the female, who is incubating her eggs in the hole beneath. 125 00:16:02,330 --> 00:16:05,380 The burrowing owls nest in holes in the ground, 126 00:16:05,540 --> 00:16:08,550 taking over ones that have been abandoned by armadillos 127 00:16:08,710 --> 00:16:11,090 or even digging them for themselves. 128 00:16:11,420 --> 00:16:16,550 The male perches on a termite hill on guard, for the chicks are about to emerge. 129 00:16:23,400 --> 00:16:25,150 Danger - a harrier. 130 00:16:37,830 --> 00:16:40,080 Now it's safe once more. 131 00:16:40,450 --> 00:16:46,630 As long as the chicks can't fly, they're in danger from armadillos, tegus and other predators. 132 00:16:46,920 --> 00:16:50,630 So it is very important that they get their flight feathers as quickly as possible, 133 00:16:50,800 --> 00:16:55,390 and already, only a couple of weeks after hatching, they are showing through the down. 134 00:17:04,690 --> 00:17:09,610 Out in the fresh air, there is space to preen and a chance to sunbathe. 135 00:17:42,180 --> 00:17:48,860 Once more there is an alarm... It's the spur-winged plovers. 136 00:17:59,820 --> 00:18:01,870 The plovers are quarrelsome birds. 137 00:18:02,040 --> 00:18:05,910 Even though each pair has established its claims over a patch of grassland, 138 00:18:06,080 --> 00:18:09,250 the birds continually dispute with their neighbours. 139 00:18:09,880 --> 00:18:13,960 Rivals display aggressively, running along the frontier between their territories 140 00:18:14,130 --> 00:18:16,220 and dive-bombing one another. 141 00:18:28,980 --> 00:18:33,070 Their nest is probably as safe as it would be even if they remained sitting on it, 142 00:18:33,360 --> 00:18:37,530 for their eggs are marvellously camouflaged and very difficult to see. 143 00:18:42,990 --> 00:18:47,790 The adult tinamou, on the other hand, is just as well-disguised as the plover's eggs. 144 00:18:48,250 --> 00:18:50,830 Its strategy is to stay put and freeze. 145 00:18:51,250 --> 00:18:55,960 Just as well, for its eggs are very conspicuous, a brilliant shiny purple. 146 00:19:01,010 --> 00:19:04,680 One ground-nester on the open plains, however, fears nothing. 147 00:19:04,930 --> 00:19:09,940 It's big enough and strong enough to take on even an armadillo or a tegu. 148 00:19:11,190 --> 00:19:14,020 The rhea, the South American ostrich. 149 00:19:16,360 --> 00:19:19,400 It's the male that makes the nest and incubates the eggs. 150 00:19:19,700 --> 00:19:25,240 And he is polygamous, with half a dozen or so females, all of whom will lay in his nest. 151 00:19:32,170 --> 00:19:37,130 But with so many contributors, the compiling of a clutch can be a tricky business. 152 00:19:37,590 --> 00:19:43,260 Sometimes several females, each with an egg ready to be laid, will turn up at the same time 153 00:19:43,430 --> 00:19:47,140 and there's some confusion as to who's going to have the first turn. 154 00:19:47,390 --> 00:19:50,600 He doesn't seem to want them to lay in the main clutch. 155 00:19:50,890 --> 00:19:56,320 Perhaps he's worried about them treading on his eggs, so they'll have to sit outside. 156 00:20:01,780 --> 00:20:03,870 The first female goes down. 157 00:20:18,300 --> 00:20:21,550 Once laid, the egg has to be brought in to join the rest of the clutch 158 00:20:21,720 --> 00:20:23,800 if he is to incubate it properly. 159 00:20:26,720 --> 00:20:29,270 Another female settles down to lay. 160 00:20:34,600 --> 00:20:37,150 And another egg joins his collection. 161 00:20:57,710 --> 00:21:01,420 His final clutch may be huge, up to 50 or so. 162 00:21:01,840 --> 00:21:06,180 They've come from many different females and been laid over a period of eight days, 163 00:21:06,340 --> 00:21:08,010 but all hatch together. 164 00:21:08,510 --> 00:21:12,100 The young pipe to one another while they're still inside their shells, 165 00:21:12,310 --> 00:21:17,400 stimulating the eggs that are a bit behind to speed up their development. 166 00:21:38,590 --> 00:21:43,210 The advantage of hatching simultaneously is that the young, soon after they emerge, 167 00:21:43,470 --> 00:21:47,140 can go off and feed together under Father's watchful eye. 168 00:22:21,880 --> 00:22:26,090 The open grassland is full of dangers and there are very few places to hide 169 00:22:26,260 --> 00:22:29,050 from the many enemies that lie in wait for the chicks. 170 00:22:29,590 --> 00:22:33,350 The maned wolf will certainly take one if it gets the chance. 171 00:22:38,020 --> 00:22:42,400 It hunts alone, never forming packs, seldom even seen with its mate. 172 00:22:42,650 --> 00:22:46,990 It maintains contact with others of its kind by an occasional bark 173 00:22:47,200 --> 00:22:52,410 and by leaving its scent on bushes and termite mounds, spraying its urine high up 174 00:22:52,660 --> 00:22:55,950 so that the wind will pick up the smell and broadcast it. 175 00:22:58,370 --> 00:23:04,710 This wolf's tastes are, oddly, strongly vegetarian. Fruit forms a large part of its diet. 176 00:23:29,360 --> 00:23:34,160 But it certainly takes birds if it can, and the tinamou is particularly vulnerable, 177 00:23:34,370 --> 00:23:36,080 for it's almost flightless. 178 00:24:23,880 --> 00:24:28,760 Trees don't grow on the open plains of Argentina and Brazil because, for much of the year, 179 00:24:28,960 --> 00:24:30,510 there is too little rain. 180 00:24:31,010 --> 00:24:35,600 During the dry season, the shallow lakes are reduced to stretches of baked mud. 181 00:24:35,800 --> 00:24:42,560 Capybara, giant semi-aquatic guinea pigs, crowd into the few shrinking pools that remain. 182 00:24:43,480 --> 00:24:46,610 Cayman are compelled to spend much of their time out of water, 183 00:24:46,820 --> 00:24:52,070 and turtles jostle for places along the contracting margins with the capybara. 184 00:24:54,780 --> 00:24:59,410 But during April, the clouds begin to gather and in June they burst. 185 00:25:11,510 --> 00:25:15,300 It's a testing time for many of the grassland creatures. 186 00:25:27,150 --> 00:25:33,400 2,000 miles north of the Brazilian campo, the grasslands of Venezuela, the llanos, 187 00:25:33,610 --> 00:25:38,700 flood over great areas, for the ground is full of clay and holds the water. 188 00:25:40,080 --> 00:25:42,580 For some, this is exactly what they want. 189 00:25:49,130 --> 00:25:53,840 The llanos are flooded like this for almost half the year. 190 00:25:54,130 --> 00:25:56,890 That's all right for those capybara. 191 00:25:57,220 --> 00:26:01,430 They are almost as much at home in the water as they are on land. 192 00:26:01,680 --> 00:26:06,140 Some creatures, even such an unlikely-looking swimmer as the giant anteater, 193 00:26:06,310 --> 00:26:08,770 manage to struggle to dry ground. 194 00:26:09,770 --> 00:26:12,900 The armadillo, too, is very competent in the water. 195 00:26:17,910 --> 00:26:22,700 Many others, such as burrowing rodents that might otherwise crop the grass of the plains, 196 00:26:22,910 --> 00:26:27,420 can't do so because they can't survive being flooded like this every year. 197 00:26:28,170 --> 00:26:32,630 The grass, however, grows tall and lives through even this hardship. 198 00:26:34,210 --> 00:26:39,800 2,000 miles farther north still, water lies on the plains for many months on end, 199 00:26:40,050 --> 00:26:43,430 as snow on the prairies of North America. 200 00:26:44,770 --> 00:26:49,270 Here the temperature can drop to 46 degrees below zero centigrade. 201 00:26:49,690 --> 00:26:53,940 The resistant grass survives it but few animals can. 202 00:26:55,610 --> 00:27:00,950 The ground squirrels retreat to their burrows and go into a state of suspended animation. 203 00:27:01,530 --> 00:27:06,040 Their temperature falls and their breathing rate slows - they hibernate, 204 00:27:06,330 --> 00:27:11,080 using the absolute minimum of their body reserves accumulated during the summer. 205 00:27:22,390 --> 00:27:26,180 A cousin of the ground squirrel, another rodent called the prairie dog, 206 00:27:26,470 --> 00:27:31,230 does remain active, and during milder spells it ventures out onto the snow 207 00:27:31,400 --> 00:27:33,190 to nibble what leaves it can find. 208 00:27:37,690 --> 00:27:43,030 The prairie chicken, actually a grouse, is one of the few birds to stay on the winter prairies, 209 00:27:43,240 --> 00:27:49,250 for although there are no insects to be had now, it can survive on nothing but seeds and leaves. 210 00:27:52,920 --> 00:27:56,420 Things are happening, however, below ground. 211 00:27:58,800 --> 00:28:01,720 The pocket gopher is still hard at work. 212 00:28:04,350 --> 00:28:07,770 Its winter food is roots, and very nourishing they are, 213 00:28:07,930 --> 00:28:11,850 for many plants in autumn withdraw much of their substance from withering leaves 214 00:28:12,020 --> 00:28:13,900 and store it in their roots. 215 00:28:19,990 --> 00:28:24,990 The bison manages to survive even the coldest weather out on the prairie. 216 00:28:25,200 --> 00:28:27,870 Big animals are not as easily chilled as small ones, 217 00:28:28,040 --> 00:28:31,580 and the bison is the most massive animal in North America. 218 00:28:32,000 --> 00:28:33,420 A bull can weigh a ton. 219 00:28:39,670 --> 00:28:43,800 The extreme temperatures have, in effect, put the grass into deep freeze, 220 00:28:44,090 --> 00:28:49,100 so that, although it's frozen solid, such nutriment as it contained is preserved. 221 00:28:49,770 --> 00:28:53,600 The bison, being so big, have no difficulty in sweeping away the snow 222 00:28:53,770 --> 00:28:55,940 and reaching the frozen tufts. 223 00:28:58,020 --> 00:29:01,900 Bison share the prairies with pronghorn antelope which, in winter, 224 00:29:02,110 --> 00:29:05,410 often visit areas that the bison have just cleared of snow. 225 00:29:05,870 --> 00:29:11,750 They are the swiftest animals in North America, capable of speeds of 50 mph at full stretch. 226 00:29:14,330 --> 00:29:20,050 Coyotes, a small relation of the wolf, have little chance of catching a young healthy pronghorn. 227 00:29:20,300 --> 00:29:23,930 But that doesn't mean they won't try, and by chasing, they can discover 228 00:29:24,130 --> 00:29:28,930 if there are any antelope in the group that are less than healthy and therefore catchable. 229 00:30:02,880 --> 00:30:05,010 Another joins the chase. 230 00:30:17,690 --> 00:30:21,900 The bitter cold and the shortage of food kills many animals at this time. 231 00:30:22,110 --> 00:30:27,740 For the coyotes, a carcass is precious, a mass of meat in an otherwise barren land. 232 00:30:28,070 --> 00:30:31,530 A pair has already taken possession of this dead elk. 233 00:30:32,990 --> 00:30:35,620 A third arrives. There will be trouble. 234 00:30:41,250 --> 00:30:47,050 They signal their threats with bristling fur, snarling lips but surprisingly little sound. 235 00:31:24,050 --> 00:31:28,550 As spring approaches, the temperature rises, even below ground, 236 00:31:28,800 --> 00:31:31,510 and the winter sleepers begin to awake. 237 00:31:35,100 --> 00:31:40,440 Rattlesnakes, forced to take shelter from the cold frequently take over the deeper burrows 238 00:31:40,600 --> 00:31:44,150 made by prairie dogs and there, ten feet below ground, 239 00:31:44,320 --> 00:31:47,820 sit out the winter beyond the reach of the lethal frost. 240 00:31:48,360 --> 00:31:52,820 Sometimes as many as two or three hundred will share the same hole. 241 00:31:53,450 --> 00:31:58,250 As the spring sun warms the air, so they too slowly come to life. 242 00:32:04,040 --> 00:32:07,800 The prairie chickens leave the tall grass country where they spent the winter 243 00:32:08,010 --> 00:32:12,640 and assemble on shorter turf, for they are about to start their spring dances. 244 00:32:35,080 --> 00:32:39,370 Each male stays on a small patch of ground that is his dancing stage, 245 00:32:39,540 --> 00:32:45,920 and there erects his feathery horns, inflates his wattles and starts his stamping dance. 246 00:33:36,890 --> 00:33:40,640 The prairie dogs live in such concentrations and such numbers 247 00:33:40,810 --> 00:33:44,140 that their patch of the prairie is called a town. 248 00:33:44,770 --> 00:33:47,480 They mated below ground back in February. 249 00:33:47,730 --> 00:33:52,030 The youngsters were born a month later and now, in the sunshine of early summer, 250 00:33:52,280 --> 00:33:54,110 they get their first view of the world. 251 00:34:19,350 --> 00:34:21,390 The bison, too, have their young. 252 00:34:21,640 --> 00:34:25,890 The thick woollen coat that protected them through the winter is now far too hot, 253 00:34:26,140 --> 00:34:29,150 and the animals begin to shed it in sheets and tatters. 254 00:34:38,450 --> 00:34:43,500 The bison, being such a big animal, has a long gestation period, nine months. 255 00:34:43,750 --> 00:34:47,290 So, soon after the young are born, courting starts again, 256 00:34:47,580 --> 00:34:50,500 and for the bulls that involves battling with rivals. 257 00:34:51,040 --> 00:34:55,090 These jousts, which can be very punishing and even end in death, 258 00:34:55,300 --> 00:34:57,970 establish a ranking among the bulls. 259 00:35:00,890 --> 00:35:05,390 The victors can then seek access to the cows, which is another problem. 260 00:35:40,140 --> 00:35:45,310 The bison herds have a particular liking for the grazing around the prairie dogs' towns, 261 00:35:45,520 --> 00:35:47,680 for the prairie dogs are good farmers. 262 00:35:47,930 --> 00:35:52,610 They deliberately cut down unpalatable plants and remove dead material, 263 00:35:52,770 --> 00:35:56,990 and their constant cropping means that the grass leaves around their burrows 264 00:35:57,150 --> 00:35:59,780 are all young and succulent, and the bison like that 265 00:35:59,990 --> 00:36:01,990 just as much as the prairie dogs do. 266 00:36:16,920 --> 00:36:22,050 The rattlesnakes also haunt the town, on the lookout for young prairie dogs. 267 00:36:22,340 --> 00:36:28,060 The shortness of the cropped turf makes it easy for the town sentinels to see approaching danger. 268 00:36:40,280 --> 00:36:42,700 What to do about it is another question. 269 00:37:01,510 --> 00:37:04,470 Bolting down a burrow is no defence against a rattlesnake. 270 00:37:04,640 --> 00:37:10,680 It will simply follow. The only thing to do is ret and whistle a warning to the neighbours. 271 00:37:19,570 --> 00:37:23,320 Bison are cattle. Like antelope and sheep, they are ruminants, 272 00:37:23,570 --> 00:37:28,740 dealing with the problem of digesting cellulose by regurgitating pellets of grass they graze 273 00:37:28,950 --> 00:37:31,040 and giving it all a second chew. 274 00:37:31,540 --> 00:37:36,250 They also maintain a digestive broth of bacteria in their huge stomachs. 275 00:37:36,580 --> 00:37:40,710 Only 150 years ago, they lived in such numbers on the prairies 276 00:37:40,960 --> 00:37:43,840 that a herd could stretch from one horizon to another. 277 00:37:44,510 --> 00:37:49,390 How many there were altogether is uncertain. Thirty million is one of the lower estimates. 278 00:37:49,640 --> 00:37:53,390 That was a measure of the great fertility of these natural grasslands. 279 00:37:54,190 --> 00:37:59,270 Today, most of the prairie has been turned over to the raising of domesticated cattle for beef, 280 00:37:59,440 --> 00:38:03,280 or ploughed up to grow domesticated grass, wheat. 281 00:38:04,030 --> 00:38:08,160 By the beginning of this century, less than a thousand wild bison were left. 282 00:38:08,330 --> 00:38:14,750 But today, thanks to careful conservation, there are some 35,000 living in reserves. 283 00:38:15,920 --> 00:38:21,460 The prairies receive comparatively little rain because they lie in the centre of a huge continent 284 00:38:21,670 --> 00:38:24,880 and the Rocky Mountains screen off the rain. 285 00:38:29,350 --> 00:38:33,350 Across the northern Pacific, the biggest continental mass of all, Eurasia, 286 00:38:33,520 --> 00:38:38,190 also contains a heartland where relatively little rain falls - 287 00:38:38,400 --> 00:38:41,610 the grass-covered steppes of Russia and Eastern Europe. 288 00:38:41,860 --> 00:38:46,910 And here another grass feeder survives that once formed vast herds, 289 00:38:47,160 --> 00:38:49,990 an extraordinary antelope, the saiga. 290 00:38:54,200 --> 00:38:58,380 Its huge nose contains, internally, a convoluted arrangement of passages 291 00:38:58,580 --> 00:39:02,550 lined with mucous glands that apparently serve to warm and moisten 292 00:39:02,750 --> 00:39:05,720 the dry air of the steppes and filter out the dust 293 00:39:16,310 --> 00:39:18,310 The steppes are not as fertile as the prairie 294 00:39:18,520 --> 00:39:21,860 and are ravaged by regular and disastrous droughts. 295 00:39:22,270 --> 00:39:27,200 But the saiga seem to have adapted to this and have a quite extraordinary rate of reproduction 296 00:39:27,360 --> 00:39:31,950 that enables them to recover their numbers after such a catastrophe with great speed. 297 00:39:32,530 --> 00:39:37,120 The females, when they are a mere four months old and only half-grown, 298 00:39:37,290 --> 00:39:39,870 mate and produce their first calf. 299 00:39:40,380 --> 00:39:44,920 After it is weaned, they grow rapidly, so that by the beginning of the next breeding season, 300 00:39:45,090 --> 00:39:49,300 they are full-size, and then they quickly breed again - and this time 301 00:39:49,470 --> 00:39:52,100 three quarters of them will produce twins. 302 00:39:53,760 --> 00:39:56,430 These animals, too, were hunted close to extinction, 303 00:39:56,640 --> 00:39:59,890 but when people realised that these natural inhabitants of the steppes 304 00:40:00,060 --> 00:40:04,320 could turn their grass into meat much more efficiently than any domesticated animal, 305 00:40:04,610 --> 00:40:10,240 indiscriminate hunting was stopped and now there are over two million in the Soviet Union. 306 00:40:12,820 --> 00:40:17,830 Travel south west from the steppes of central Eurasia, the greatest of all temperate grasslands, 307 00:40:18,080 --> 00:40:22,080 across territory where there is so little rain that not even grass can grow, 308 00:40:22,330 --> 00:40:27,090 and you come to the greatest of all tropical grasslands - in Africa. 309 00:40:35,560 --> 00:40:38,600 Here there is enough rain to create rivers and waterholes, 310 00:40:38,850 --> 00:40:44,610 so in the moist soils around them and on rocky outcrops, a few trees manage to grow. 311 00:40:46,940 --> 00:40:51,660 In the more regularly watered parts, thorn trees stand, distanced from one another, 312 00:40:51,910 --> 00:40:56,580 their widespread root-systems managing to collect just enough water to sustain them. 313 00:40:57,160 --> 00:40:59,950 Elsewhere, there is only enough rainfall for grass 314 00:41:02,000 --> 00:41:05,380 But young trees are threatened not only by drought but by fire. 315 00:41:05,790 --> 00:41:09,050 It sweeps rapidly over the plains, killing the tree seedlings 316 00:41:09,260 --> 00:41:14,010 but leaving the growing buds of the grasses, close to the ground, quite unharmed, 317 00:41:14,340 --> 00:41:17,260 and green shoots of grass appear within days. 318 00:41:17,470 --> 00:41:21,230 So the fire, which starts so easily in withered grass stems, 319 00:41:21,480 --> 00:41:25,440 is one of the factors that keeps the country open, for grass. 320 00:41:28,820 --> 00:41:34,780 The grasslands of Africa stretch in an immense and almost continuous arc 321 00:41:34,950 --> 00:41:39,700 from the Sahara in the north down through East Africa 322 00:41:39,950 --> 00:41:44,540 and on to the great game plains of Southern Africa and the Cape. 323 00:41:44,790 --> 00:41:51,260 During the eight million years or so of recent history, they've varied quite a lot in their extent 324 00:41:51,460 --> 00:41:55,260 and at the moment, they are not as big as they have been in the past. 325 00:41:55,470 --> 00:42:01,100 But during this period of time, the grasslands have developed, and as they have done so, 326 00:42:01,310 --> 00:42:03,890 the animals that lived on them have evolved, 327 00:42:04,100 --> 00:42:07,270 the nature of one reacting on the nature of the other. 328 00:42:07,440 --> 00:42:13,070 Today, there's a greater variety and a bigger concentration of grass-living creatures 329 00:42:13,280 --> 00:42:16,820 on these African plains than anywhere else in the world. 330 00:42:31,130 --> 00:42:35,380 Different lengths of neck, different sets of teeth, different appetites, 331 00:42:35,550 --> 00:42:40,430 such variety means that almost every growing leaf, short or long, 332 00:42:40,640 --> 00:42:44,730 of every kind of plains plant, is eaten by something. 333 00:42:56,570 --> 00:43:00,660 This vast tonnage of meat on the hoof has led, inevitably, 334 00:43:00,830 --> 00:43:04,330 to the appearance of an abundance of meat-eaters. 335 00:43:06,370 --> 00:43:10,210 And they too are varied, to exploit the variety of meat available. 336 00:43:12,050 --> 00:43:14,210 The serval seeks mice. 337 00:43:31,110 --> 00:43:35,780 The lions, hunting in teams, butcher wildebeest and zebra. 338 00:43:39,740 --> 00:43:41,660 Hunting dogs do the same. 339 00:43:45,410 --> 00:43:49,040 The cheetah goes for animals its own size, gazelle. 340 00:44:17,940 --> 00:44:21,780 Before grass spread over the plains, the ancestors of grazing antelopes 341 00:44:21,950 --> 00:44:25,660 must have lived in bush country, rather as dik-dik do today. 342 00:44:26,330 --> 00:44:29,080 The bushes don't produce many leaves, but they are highly nutritious 343 00:44:29,250 --> 00:44:33,840 and there are enough in an acre or so to sustain a pair of these tiny antelope. 344 00:44:34,210 --> 00:44:38,420 So the dik-dik mate for life and are permanent residents of their territory. 345 00:44:38,800 --> 00:44:42,340 They know it intimately and have their own trails and hiding places, 346 00:44:42,510 --> 00:44:45,600 and they mark out its frontiers with special notices. 347 00:44:47,390 --> 00:44:51,520 The ritual is nearly always the same. The female visits the midden first. 348 00:44:52,940 --> 00:44:57,650 The buck is stimulated to follow and habitually goes through exactly the same sequence 349 00:44:57,820 --> 00:45:01,740 of smelling, urinating, scratching and dunging. 350 00:45:23,180 --> 00:45:28,180 When the ceremony is over, the buck marks the nearby bushes with a sticky perfumed wax 351 00:45:28,350 --> 00:45:30,480 from a gland just below his eyes. 352 00:45:34,770 --> 00:45:40,650 Impala, however, live in more open country and feed not only on bushes but on grass. 353 00:45:40,900 --> 00:45:45,370 Here they can't hide and they find their safety in numbers. 354 00:45:45,740 --> 00:45:49,450 With so many sharp eyes and acute ears, it's very difficult for a hunter 355 00:45:49,620 --> 00:45:51,450 to approach them undetected. 356 00:45:52,040 --> 00:45:55,460 But such a lifestyle obviously makes it impossible for the animals to live 357 00:45:55,670 --> 00:45:59,500 in permanent pairs on their own territory as the dik-dik do. 358 00:46:00,010 --> 00:46:03,170 Instead, the males and females form separate herds. 359 00:46:03,970 --> 00:46:06,260 The bucks then battle among themselves. 360 00:46:06,640 --> 00:46:11,730 Those that win will leave the bachelor herds and set up individual territories. 361 00:46:22,820 --> 00:46:27,780 When the victors have established themselves, the does visit them, one after the other. 362 00:46:28,030 --> 00:46:34,040 It is a very exhausting business for the bucks, repeatedly mating and fighting off challengers. 363 00:46:56,520 --> 00:47:00,980 After about three months of this, the once dominant bucks are worn out. 364 00:47:01,230 --> 00:47:06,360 They yield to other, fresher males and return to the bachelor herd to recover. 365 00:47:11,830 --> 00:47:14,330 Wildebeest live on grass alone. 366 00:47:14,580 --> 00:47:17,580 But the patchy distribution of rain over the African plains 367 00:47:17,750 --> 00:47:21,750 means that they can't stay permanently in the same place. 368 00:47:22,340 --> 00:47:27,180 They quickly exhaust pasture on one patch of the plains and must move to an area 369 00:47:27,340 --> 00:47:31,220 where rain has recently fallen and the grass is springing again. 370 00:47:31,640 --> 00:47:36,180 So the wildebeest are constantly on the move and their social arrangements 371 00:47:36,390 --> 00:47:39,730 have to be different from the dik-dik and impala. 372 00:47:40,150 --> 00:47:46,110 During the short breeding season, the males set up small territories along the migration routes. 373 00:47:46,400 --> 00:47:50,620 They advertise their pretensions by prancing around and snorting, 374 00:47:50,820 --> 00:47:57,790 seeking showy contests with rivals to demonstrate their virility to passing females. 375 00:48:07,760 --> 00:48:10,720 The problem then is to keep the females in their territory 376 00:48:10,890 --> 00:48:14,560 and prevent them from moving on to a rival's patch. 377 00:48:32,410 --> 00:48:35,540 The young calves, born only a few months before, 378 00:48:35,740 --> 00:48:42,710 adopt very early the jaunty, slightly crazy way of carrying on affected by their fathers. 379 00:49:03,020 --> 00:49:07,280 Within two weeks, the majority of the females are mated. 380 00:49:13,070 --> 00:49:20,120 And then, suddenly, almost overnight, the whole herd, hundreds of thousands strong, vanishes. 381 00:49:20,660 --> 00:49:23,170 They've gone in search of fresh pastures. 382 00:49:25,380 --> 00:49:31,090 The varying growth of the grass over the year affects the lives of people as well as animals. 383 00:49:31,510 --> 00:49:34,090 In the eastern part of the grasslands, in the Sudan, 384 00:49:34,300 --> 00:49:37,390 the people keep herds of semi-domesticated cattle. 385 00:49:38,140 --> 00:49:41,810 These are their pride and their wealth and their livelihood. 386 00:49:44,650 --> 00:49:50,820 At night they pen them in enclosures made from uprooted thorn bush, to keep out lion. 387 00:49:55,320 --> 00:50:00,450 The people can't settle in permanent villages, for their cattle exhaust the meagre pasture, 388 00:50:00,620 --> 00:50:05,500 just as wildebeest do, so periodically they too have to move. 389 00:50:05,960 --> 00:50:09,670 It is a nice question as to whether the animals are being driven by the people 390 00:50:09,840 --> 00:50:13,930 or whether the people are, willy-nilly, following the herds. 391 00:50:18,760 --> 00:50:24,690 Many people in the Sudan regard not only their semi-wild cattle as their own personal property, 392 00:50:24,850 --> 00:50:30,030 but also the fully wild game that regularly passes through their territory. 393 00:50:31,570 --> 00:50:36,530 The white-eared kob, the males black and white, the females a delicate tan, 394 00:50:36,700 --> 00:50:38,580 live in the southern Sudan. 395 00:50:39,330 --> 00:50:43,040 Here, during the rainy season, the does give birth to their young. 396 00:50:44,960 --> 00:50:50,210 As the rains end and the plains begin to dry out, the herds begin to move north, 397 00:50:50,460 --> 00:50:54,470 following the new flush of grass that springs from the receding waters. 398 00:50:57,510 --> 00:50:59,680 As they go, the herds are funnelled together 399 00:50:59,890 --> 00:51:05,560 by two rivers that flow closer and closer to one another until eventually they join 400 00:51:05,770 --> 00:51:09,360 and the kob have no alternative but to attempt to cross - 401 00:51:09,560 --> 00:51:13,030 and here the Merle people await them. 402 00:51:18,240 --> 00:51:22,660 For the Merle, this is an annual bonanza and a great celebration. 403 00:51:22,830 --> 00:51:26,210 Families have travelled from all over the tribal territory to take part 404 00:51:26,370 --> 00:51:29,000 and to claim their share in their harvest of meat. 405 00:51:29,380 --> 00:51:34,260 If all goes well, there will be great feasting. But that's by no means a certainty. 406 00:51:34,460 --> 00:51:38,050 If the herds don't appear, there will be real hunger in the tribe. 407 00:51:47,440 --> 00:51:51,560 In the early morning, the hunters cross the river to set up their ambush. 408 00:51:51,940 --> 00:51:54,440 There's no guarantee that the kob will come this way. 409 00:51:54,730 --> 00:51:59,410 If the rivers are low, they may well try to cross on a much broader front upstream. 410 00:52:32,190 --> 00:52:36,360 For the kob now, there is no going back. They have to cross. 411 00:53:05,810 --> 00:53:10,890 Day after day, the kob that have arrived at this crossing attempt to run the gauntlet. 412 00:53:57,730 --> 00:54:01,400 It takes several weeks for the whole migration to pass through. 413 00:54:02,650 --> 00:54:07,660 A million kob will make the journey. 5,000 of them will be killed. 414 00:54:08,160 --> 00:54:10,040 The Merle not only feast well now, 415 00:54:10,200 --> 00:54:15,540 they sun-dry the meat so that the families will have full stomachs for many months to come. 416 00:54:26,930 --> 00:54:33,180 In spite of the Merle's ambush, the vast majority of the kob reach the northern grasslands. 417 00:54:34,270 --> 00:54:39,320 There they will find enough food to sustain them throughout the critical months of the dry season. 418 00:54:39,480 --> 00:54:44,860 And there, too, they mate, so that next year herds will reappear to make the river crossing 419 00:54:45,030 --> 00:54:47,450 and provide the Merle, once more, with meat. 420 00:54:50,450 --> 00:54:52,500 And the grass, too, will spring again, 421 00:54:52,660 --> 00:54:59,250 this remarkable plant that can survive intense grazing and burning and flooding. 422 00:54:59,590 --> 00:55:02,550 The one thing it can't tolerate is drought. 423 00:55:02,840 --> 00:55:08,760 If there is just a little less rain, then its leaves wither, its roots shrivel 424 00:55:08,930 --> 00:55:12,720 and can no longer hold the soil together, so that the wind can catch it 425 00:55:12,890 --> 00:55:15,810 and blow away the small nutritious particles. 426 00:55:16,100 --> 00:55:21,520 And then it's reduced to little more than sand and the land becomes a desert.