1 00:01:04,631 --> 00:01:08,965 These beautiful flowers belong to one of the most successful, 2 00:01:09,269 --> 00:01:12,067 the most widespread and the commonest of plants. 3 00:01:16,042 --> 00:01:19,500 There are about 10,000 species in this one family, 4 00:01:19,813 --> 00:01:23,943 and they claim over a quarter of all the vegetated land on earth. 5 00:01:24,317 --> 00:01:28,617 They are pollinated by the wind, they need far less water than most trees, 6 00:01:28,822 --> 00:01:34,124 and they can survive both burning and freezing. They are the grasses. 7 00:01:41,768 --> 00:01:46,000 These tough, persistent plants continue to grow even when they're trimmed 8 00:01:46,172 --> 00:01:49,300 day after day by grazing teeth. 9 00:01:50,677 --> 00:01:52,872 They are able to withstand all this rough treatment 10 00:01:53,046 --> 00:01:56,538 because the point from which a grass leaf grows is at its base 11 00:01:56,716 --> 00:01:59,549 close to the ground and is permanently active. 12 00:01:59,853 --> 00:02:05,587 So grass provides a continuous banquet for creatures big and small. 13 00:02:11,698 --> 00:02:16,158 Down among the tangled grass stems live not only creatures that eat grass 14 00:02:16,436 --> 00:02:19,496 but others that feed on the grass-eaters. 15 00:02:20,440 --> 00:02:25,935 Lizards snap up small insects and mantis munch grasshoppers. 16 00:02:37,257 --> 00:02:40,192 Spiders tackle almost any creature that moves 17 00:02:40,360 --> 00:02:43,761 and dung beetles clear up the droppings from above. 18 00:02:45,031 --> 00:02:49,263 Among the most industrious of these tiny labourers are the termites. 19 00:02:49,569 --> 00:02:54,199 On many tropical grasslands, they flourish in such numbers that, one way or another, 20 00:02:54,407 --> 00:02:59,868 they consume more of the grass than big creatures like antelope, cows or kangaroo. 21 00:03:04,250 --> 00:03:09,586 In Brazil's savannahs, there are more termite mounds per acre than anywhere in the world. 22 00:03:09,822 --> 00:03:11,722 And termites are highly nutritious - 23 00:03:11,991 --> 00:03:18,692 so much so that the giant anteater can exist by feeding on them and nothing else whatever. 24 00:03:23,570 --> 00:03:28,735 This creature has very poor eyesight and very poor hearing, 25 00:03:29,309 --> 00:03:35,248 and finds its way around mostly by smell, so, as long as I keep downwind of it, 26 00:03:35,448 --> 00:03:40,147 there's no reason why it should be particularly disturbed by my presence. 27 00:03:40,887 --> 00:03:43,981 You might think that that would make it very vulnerable to enemies. 28 00:03:44,324 --> 00:03:48,454 The fact is, out on the savannahs here, it's got very few enemies. 29 00:03:48,628 --> 00:03:55,261 The only things that might attack it are a jaguar or a puma, or if it was a baby, a savannah fox. 30 00:03:55,568 --> 00:03:59,436 And it has a very good defence against such creatures. 31 00:03:59,806 --> 00:04:05,836 Those huge forelegs, with enormous muscles on them and gigantic claws, 32 00:04:06,179 --> 00:04:12,243 are quite powerful enough to rip the stomach from a puma or a jaguar. 33 00:04:13,052 --> 00:04:19,082 It was always thought that those legs are actually for ripping open termite hills, 34 00:04:19,325 --> 00:04:22,886 and they may be used to some extent for that purpose. 35 00:04:23,062 --> 00:04:27,192 But it seems more likely now that they are primarily defensive weapons, 36 00:04:27,367 --> 00:04:29,358 because when they actually come to feed, 37 00:04:29,535 --> 00:04:33,062 this creature doesn't do so much of a sweep with its front claws 38 00:04:33,239 --> 00:04:39,644 as to use them very, very carefully to open the exit tunnels in the termite hills. 39 00:04:40,980 --> 00:04:44,416 Once it has done that, it pokes its nose into the tunnel entrance 40 00:04:44,584 --> 00:04:48,384 and flicks out its 20-inch-long tongue, coated with sticky mucus, 41 00:04:48,554 --> 00:04:52,581 and picks off the worker termites clinging to the tunnel walls. 42 00:04:59,332 --> 00:05:03,200 After about half a minute, before the soldier termites - which have powerful bites - 43 00:05:03,403 --> 00:05:07,772 can rally to the defence of the opened tunnel, the anteater moves on. 44 00:05:08,941 --> 00:05:12,968 It is a wanderer, always on the move, sleeping at night out in the open, 45 00:05:13,246 --> 00:05:17,012 blanketed against the cold by its huge hairy tail. 46 00:05:22,755 --> 00:05:27,658 Having no permanent den, the female carries her youngster with her, piggyback. 47 00:05:45,178 --> 00:05:48,614 Other termite hunters live on the surface of the mounds themselves. 48 00:05:48,881 --> 00:05:53,545 Beetle larvae lurk in burrows and lure flying ants and other insects to them 49 00:05:53,720 --> 00:05:56,211 by the luminous glow of their heads. 50 00:06:22,715 --> 00:06:27,118 Sometimes the termite mounds are attacked at their very foundations. 51 00:06:27,587 --> 00:06:31,045 This is the biggest insect-eater on earth, the giant armadillo, 52 00:06:31,224 --> 00:06:33,920 a massive animal that weighs over a hundredweight. 53 00:06:34,327 --> 00:06:35,919 There are few more powerful diggers. 54 00:06:36,262 --> 00:06:39,026 It's no finicky eater like the giant anteater, 55 00:06:39,198 --> 00:06:42,725 but rips its way through the ground into the heart of the termite hill. 56 00:06:47,073 --> 00:06:50,531 With its defences breached, the termite colony is very vulnerable. 57 00:06:50,910 --> 00:06:54,903 This mouse, oxymicterus, has a particular fondness for termites 58 00:06:55,081 --> 00:06:58,107 and regularly follows in the wake of the giant armadillo. 59 00:07:00,987 --> 00:07:03,751 But the termites' biggest enemies are even smaller. 60 00:07:04,824 --> 00:07:10,660 Carnivorous ants regularly raid the colonies, carrying off the helpless, pallid termite larvae. 61 00:07:12,298 --> 00:07:16,325 The defenders of the colony, the soldier termites, engage the enemy ants. 62 00:07:22,742 --> 00:07:25,939 These termite warriors have jaws so specialised for fighting 63 00:07:26,112 --> 00:07:30,048 that they can't feed for themselves and have to be tended by the workers. 64 00:07:31,284 --> 00:07:33,650 Each species is armed in its own way. 65 00:07:36,923 --> 00:07:39,983 Some have short nippers, some sharp shears. 66 00:07:40,226 --> 00:07:45,027 Others have blades that strike outwards and others nozzles on their forehead 67 00:07:45,198 --> 00:07:48,395 through which they squirt a sticky poison spray. 68 00:08:06,686 --> 00:08:09,484 Other ants are vegetarians, like the termites, 69 00:08:09,789 --> 00:08:14,624 and use theirjaws to demolish the living grass plants, scissoring up the leaves, 70 00:08:14,827 --> 00:08:18,319 sawing through the stems and carrying off the plant piecemeal. 71 00:08:22,602 --> 00:08:27,904 Grass consists largely of cellulose and that is a very difficult substance to digest. 72 00:08:28,174 --> 00:08:31,473 Termites do it with the help of bacteria in their gut. 73 00:08:31,944 --> 00:08:35,380 The grass-cutting ants have another and quite extraordinary method 74 00:08:35,548 --> 00:08:38,016 of making its nutriment digestible. 75 00:08:38,484 --> 00:08:41,453 Laboriously, they haul the pieces of grass back to their nest, 76 00:08:41,621 --> 00:08:46,524 which may be as much as 100 yards away and have several hundred small entrances. 77 00:08:49,061 --> 00:08:53,828 Inside an entrance, a tunnel leads down into a vast labyrinth of corridors 78 00:08:54,000 --> 00:08:58,061 that may extend for 80 or 90 feet in a horizontal direction 79 00:08:58,237 --> 00:09:02,298 and lead to as many as 2,000 interlinked chambers. 80 00:09:06,312 --> 00:09:10,840 Such a nest may contain as many as 20 million ants. 81 00:09:19,225 --> 00:09:23,127 The workers carry their cuttings deeper and deeper into the nest. 82 00:09:27,199 --> 00:09:32,136 And here, 15 feet below the surface of the ground, in special chambers, 83 00:09:32,405 --> 00:09:35,636 they feed the grass to a fungus. 84 00:09:36,475 --> 00:09:42,573 This fungus forms crumbly white lumps and grows nowhere else but in these nests. 85 00:09:44,984 --> 00:09:48,112 Carefully, the ant gardeners clean every fragment of grass. 86 00:09:48,321 --> 00:09:51,848 Meticulously, they remove every spore of any other fungus 87 00:09:52,024 --> 00:09:56,358 that might grow down here if it got the chance. Weeds, as you might say. 88 00:09:56,862 --> 00:09:59,990 The waxy skin that covers the leaf surface is stripped away 89 00:10:00,166 --> 00:10:03,966 and then the pieces are cut up into even smaller fragments. 90 00:10:09,942 --> 00:10:14,641 The gardeners push the prepared morsels of grass into the mass of the fungus. 91 00:10:14,914 --> 00:10:18,748 The fungus digests it, cellulose and all, and grows, 92 00:10:18,918 --> 00:10:24,481 and the ants then feed on the fungus, which, unlike grass, they can digest. 93 00:10:35,835 --> 00:10:38,565 The ants tend their gardens with great care. 94 00:10:38,871 --> 00:10:42,568 Dead pieces of fungus and coarse, unsuitable fragments of leaves 95 00:10:42,742 --> 00:10:45,677 are carefully removed and carried away. 96 00:10:52,151 --> 00:10:58,181 With unflagging energy, porter lines of ants carry the waste down the long corridors 97 00:10:58,357 --> 00:11:05,195 to the lowest chambers of all, 20 feet below ground, that serve as the colony's refuse tips. 98 00:11:17,143 --> 00:11:20,977 These are not only rubbish dumps, but cemeteries, 99 00:11:21,147 --> 00:11:25,106 for here they also bring the bodies of dead workers. 100 00:11:37,363 --> 00:11:41,823 Dawn on the grasslands of Brazil, the campo. 101 00:11:55,047 --> 00:11:58,016 It's still chilly and the dew lies heavily. 102 00:11:58,317 --> 00:12:03,755 But the rising sun will soon dry out the pasturage and rouse the daytime inhabitants. 103 00:12:29,982 --> 00:12:36,478 The grassland birds have no trees from which to sing. Some make do with grass stems. 104 00:12:37,123 --> 00:12:42,891 Others, like the scissor-tailed flycatcher, proclaim their territorial rights by visual displa 105 00:12:43,062 --> 00:12:47,499 flying incessantly and conspicuously above their chosen plots. 106 00:13:03,315 --> 00:13:10,153 The seriama, a catcher of snakes and insects, surveys the prospects from a termite hill. 107 00:13:11,657 --> 00:13:15,149 The tapir has browsed throughout the night, but now, as the sun rises, 108 00:13:15,327 --> 00:13:19,627 it makes its way back to the forest that grows in the moist ground beside the river, 109 00:13:19,799 --> 00:13:26,466 for it prefers that shady obscurity to the hot conspicuousness of the daytime plains. 110 00:13:32,344 --> 00:13:37,805 On the other hand, the savannah deer has slept all night and only grazes when it is lig 111 00:13:38,284 --> 00:13:40,548 It prefers to be able to see its enemies. 112 00:13:43,289 --> 00:13:48,420 The armadillo is no grass-eater. It's looking for insects, roots and birds' eggs, 113 00:13:48,594 --> 00:13:50,926 and even a lizard or a small snake. 114 00:13:56,669 --> 00:14:00,469 As the day warms up, reptiles become active. 115 00:14:04,310 --> 00:14:09,009 The tegu lizard is sufficiently powerful to be able to take on all-comers. 116 00:14:10,282 --> 00:14:17,085 Just what it likes, and no small bird, no matter how aggressive, is able to repel a hungry tegu. 117 00:14:30,970 --> 00:14:34,133 Eggs on the ground are very much at risk from creatures like this. 118 00:14:34,306 --> 00:14:38,072 But where else can you put them? There are few trees on the grassland. 119 00:14:38,611 --> 00:14:40,738 But there are termite hills. 120 00:14:45,351 --> 00:14:48,718 The flicker is a kind of woodpecker and drills into termite hills 121 00:14:48,888 --> 00:14:52,324 just as efficiently as its cousins do into tree trunks. 122 00:14:54,860 --> 00:14:59,263 And when the flicker has finished with its hole, kestrels often take it over. 123 00:15:05,404 --> 00:15:06,894 The male has a lizard. 124 00:15:07,139 --> 00:15:11,576 Softly, he summons the female, who is incubating her eggs in the hole beneath. 125 00:15:22,454 --> 00:15:25,355 The burrowing owls nest in holes in the ground, 126 00:15:25,524 --> 00:15:28,391 taking over ones that have been abandoned by armadillos 127 00:15:28,560 --> 00:15:30,858 or even digging them for themselves. 128 00:15:31,163 --> 00:15:36,066 The male perches on a termite hill on guard, for the chicks are about to emerge. 129 00:15:42,641 --> 00:15:44,302 Danger - a harrier. 130 00:15:56,488 --> 00:15:58,649 Now it's safe once more. 131 00:15:58,991 --> 00:16:04,930 As long as the chicks can't fly, they're in danger from armadillos, tegus and other predators. 132 00:16:05,197 --> 00:16:08,758 So it is very important that they get their flight feathers as quickly as possible, 133 00:16:08,934 --> 00:16:13,303 and already, only a couple of weeks after hatching, they are showing through the down. 134 00:16:22,247 --> 00:16:26,980 Out in the fresh air, there is space to preen and a chance to sunbathe. 135 00:16:58,217 --> 00:17:04,588 Once more there is an alarm... It's the spur-winged plovers. 136 00:17:15,100 --> 00:17:17,068 The plovers are quarrelsome birds. 137 00:17:17,236 --> 00:17:20,967 Even though each pair has established its claims over a patch of grassland, 138 00:17:21,140 --> 00:17:24,166 the birds continually dispute with their neighbours. 139 00:17:24,777 --> 00:17:28,679 Rivals display aggressively, running along the frontier between their territories 140 00:17:28,847 --> 00:17:30,838 and dive-bombing one another. 141 00:17:43,095 --> 00:17:46,997 Their nest is probably as safe as it would be even if they remained sitting on it, 142 00:17:47,266 --> 00:17:51,293 for their eggs are marvellously camouflaged and very difficult to see. 143 00:17:56,508 --> 00:18:01,138 The adult tinamou, on the other hand, is just as well-disguised as the plover's eggs. 144 00:18:01,547 --> 00:18:04,038 Its strategy is to stay put and freeze. 145 00:18:04,450 --> 00:18:08,944 Just as well, for its eggs are very conspicuous, a brilliant shiny purple. 146 00:18:13,792 --> 00:18:17,319 One ground-nester on the open plains, however, fears nothing. 147 00:18:17,563 --> 00:18:22,364 It's big enough and strong enough to take on even an armadillo or a tegu. 148 00:18:23,569 --> 00:18:26,265 The rhea, the South American ostrich. 149 00:18:28,507 --> 00:18:31,442 It's the male that makes the nest and incubates the eggs. 150 00:18:31,710 --> 00:18:37,046 And he is polygamous, with half a dozen or so females, all of whom will lay in his nest. 151 00:18:43,689 --> 00:18:48,456 But with so many contributors, the compiling of a clutch can be a tricky business. 152 00:18:48,861 --> 00:18:54,322 Sometimes several females, each with an egg ready to be laid, will turn up at the same time 153 00:18:54,500 --> 00:18:58,027 and there's some confusion as to who's going to have the first turn. 154 00:18:58,270 --> 00:19:01,364 He doesn't seem to want them to lay in the main clutch. 155 00:19:01,640 --> 00:19:06,839 Perhaps he's worried about them treading on his eggs, so they'll have to sit outside. 156 00:19:12,084 --> 00:19:14,075 The first female goes down. 157 00:19:27,933 --> 00:19:31,027 Once laid, the egg has to be brought in to join the rest of the clutch 158 00:19:31,203 --> 00:19:33,194 if he is to incubate it properly. 159 00:19:36,008 --> 00:19:38,442 Another female settles down to lay. 160 00:19:43,549 --> 00:19:46,017 And another egg joins his collection. 161 00:20:05,737 --> 00:20:09,264 His final clutch may be huge, up to 50 or so. 162 00:20:09,675 --> 00:20:13,839 They've come from many different females and been laid over a period of eight days, 163 00:20:14,012 --> 00:20:15,604 but all hatch together. 164 00:20:16,081 --> 00:20:19,539 The young pipe to one another while they're still inside their shells, 165 00:20:19,718 --> 00:20:24,587 stimulating the eggs that are a bit behind to speed up their development. 166 00:20:44,910 --> 00:20:49,370 The advantage of hatching simultaneously is that the young, soon after they emerge, 167 00:20:49,615 --> 00:20:53,107 can go off and feed together under Father's watchful eye. 168 00:21:26,451 --> 00:21:30,478 The open grassland is full of dangers and there are very few places to hide 169 00:21:30,656 --> 00:21:33,318 from the many enemies that lie in wait for the chicks. 170 00:21:33,859 --> 00:21:37,454 The maned wolf will certainly take one if it gets the chance. 171 00:21:41,933 --> 00:21:46,131 It hunts alone, never forming packs, seldom even seen with its mate. 172 00:21:46,371 --> 00:21:50,535 It maintains contact with others of its kind by an occasional bark 173 00:21:50,709 --> 00:21:55,703 and by leaving its scent on bushes and termite mounds, spraying its urine high up 174 00:21:55,947 --> 00:21:59,110 so that the wind will pick up the smell and broadcast it. 175 00:22:01,420 --> 00:22:07,518 This wolf's tastes are, oddly, strongly vegetarian. Fruit forms a large part of its diet. 176 00:22:31,149 --> 00:22:35,779 But it certainly takes birds if it can, and the tinamou is particularly vulnerable, 177 00:22:35,954 --> 00:22:37,615 for it's almost flightless. 178 00:23:23,435 --> 00:23:28,134 Trees don't grow on the open plains of Argentina and Brazil because, for much of the year, 179 00:23:28,306 --> 00:23:29,796 there is too little rain. 180 00:23:30,275 --> 00:23:34,678 During the dry season, the shallow lakes are reduced to stretches of baked mud. 181 00:23:34,880 --> 00:23:41,342 Capybara, giant semi-aquatic guinea pigs, crowd into the few shrinking pools that remain. 182 00:23:42,254 --> 00:23:45,246 Cayman are compelled to spend much of their time out of water, 183 00:23:45,424 --> 00:23:50,487 and turtles jostle for places along the contractin margins with the capybara. 184 00:23:53,064 --> 00:23:57,501 But during April, the clouds begin to gather and in June they burst. 185 00:24:09,114 --> 00:24:12,777 It's a testing time for many of the grassland creatures. 186 00:24:24,129 --> 00:24:30,125 2,000 miles north of the Brazilian campo, the grasslands of Venezuela, the llanos, 187 00:24:30,302 --> 00:24:35,205 flood over great areas, for the ground is full of clay and holds the water. 188 00:24:36,508 --> 00:24:38,908 For some, this is exactly what they want. 189 00:24:45,217 --> 00:24:49,711 The llanos are flooded like this for almost half the year. 190 00:24:49,988 --> 00:24:52,650 That's all right for those capybara. 191 00:24:52,958 --> 00:24:56,985 They are almost as much at home in the water as they are on land. 192 00:24:57,229 --> 00:25:01,529 Some creatures, even such an unlikely-looking swimmer as the giant anteater, 193 00:25:01,700 --> 00:25:04,032 manage to struggle to dry ground. 194 00:25:05,003 --> 00:25:07,995 The armadillo, too, is very competent in the water. 195 00:25:12,811 --> 00:25:17,407 Many others, such as burrowing rodents that might otherwise crop the grass of the plains, 196 00:25:17,582 --> 00:25:21,916 can't do so because they can't survive being flooded like this every year. 197 00:25:22,621 --> 00:25:26,921 The grass, however, grows tall and lives through even this hardship. 198 00:25:28,426 --> 00:25:33,796 2,000 miles farther north still, water lies on the plains for many months on end, 199 00:25:34,032 --> 00:25:37,297 as snow on the prairies of North America. 200 00:25:38,570 --> 00:25:42,870 Here the temperature can drop to 46 degrees below zero centigrade. 201 00:25:43,275 --> 00:25:47,371 The resistant grass survives it but few animals can. 202 00:25:48,980 --> 00:25:54,077 The ground squirrels retreat to their burrows and go into a state of suspended animation. 203 00:25:54,653 --> 00:25:58,953 Their temperature falls and their breathing rate slows - they hibernate, 204 00:25:59,257 --> 00:26:03,819 using the absolute minimum of their body reserves accumulated during the summer. 205 00:26:14,639 --> 00:26:18,268 A cousin of the ground squirrel, another rodent called the prairie dog, 206 00:26:18,543 --> 00:26:23,105 does remain active, and during milder spells it ventures out onto the snow 207 00:26:23,281 --> 00:26:25,010 to nibble what leaves it can find. 208 00:26:29,321 --> 00:26:34,452 The prairie chicken, actually a grouse, is one of the few birds to stay on the winter prairies, 209 00:26:34,626 --> 00:26:40,394 for although there are no insects to be had now, it can survive on nothing but seeds and leaves. 210 00:26:43,935 --> 00:26:47,268 Things are happening, however, below ground. 211 00:26:49,574 --> 00:26:52,372 The pocket gopher is still hard at work. 212 00:26:54,879 --> 00:26:58,144 Its winter food is roots, and very nourishing they are, 213 00:26:58,316 --> 00:27:02,082 for many plants in autumn withdraw much of their substance from withering leaves 214 00:27:02,253 --> 00:27:04,050 and store it in their roots. 215 00:27:09,861 --> 00:27:14,662 The bison manages to survive even the coldest weather out on the prairie. 216 00:27:14,899 --> 00:27:17,424 Big animals are not as easily chilled as small ones, 217 00:27:17,602 --> 00:27:21,003 and the bison is the most massive animal in North America. 218 00:27:21,406 --> 00:27:22,771 A bull can weigh a ton. 219 00:27:28,747 --> 00:27:32,740 The extreme temperatures have, in effect, put the grass into deep freeze, 220 00:27:33,018 --> 00:27:37,819 so that, although it's frozen solid, such nutriment as it contained is preserved. 221 00:27:38,456 --> 00:27:42,119 The bison, being so big, have no difficulty in sweeping away the snow 222 00:27:42,293 --> 00:27:44,352 and reaching the frozen tufts. 223 00:27:46,364 --> 00:27:50,095 Bison share the prairies with pronghorn antelope which, in winter, 224 00:27:50,268 --> 00:27:53,431 often visit areas that the bison have just cleared of snow. 225 00:27:53,872 --> 00:27:59,538 They are the swiftest animals in North America, capable of speeds of 50 mph at full stretch. 226 00:28:01,980 --> 00:28:07,475 Coyotes, a small relation of the wolf, have little chance of catching a young healthy pronghorn. 227 00:28:07,719 --> 00:28:11,211 But that doesn't mean they won't try, and by chasing, they can discover 228 00:28:11,389 --> 00:28:16,019 if there are any antelope in the group that are less than healthy and therefore catchable. 229 00:28:48,560 --> 00:28:50,585 Anotherjoins the chase. 230 00:29:02,774 --> 00:29:06,801 The bitter cold and the shortage of food kills many animals at this time. 231 00:29:07,011 --> 00:29:12,415 For the coyotes, a carcass is precious, a mass of meat in an otherwise barren land. 232 00:29:12,717 --> 00:29:16,050 A pair has already taken possession of this dead elk. 233 00:29:17,455 --> 00:29:19,946 A third arrives. There will be trouble. 234 00:29:25,363 --> 00:29:30,926 They signal their threats with bristling fur, snarling lips but surprisingly little sound. 235 00:30:06,404 --> 00:30:10,704 As spring approaches, the temperature rises, even below ground, 236 00:30:10,975 --> 00:30:13,569 and the winter sleepers begin to awake. 237 00:30:17,015 --> 00:30:22,112 Rattlesnakes, forced to take shelter from the cold frequently take over the deeper burrows 238 00:30:22,287 --> 00:30:25,688 made by prairie dogs and there, ten feet below ground, 239 00:30:25,857 --> 00:30:29,190 sit out the winter beyond the reach of the lethal frost. 240 00:30:29,727 --> 00:30:33,993 Sometimes as many as two or three hundred will share the same hole. 241 00:30:34,599 --> 00:30:39,195 As the spring sun warms the air, so they too slowly come to life. 242 00:30:44,742 --> 00:30:48,371 The prairie chickens leave the tall grass country where they spent the winter 243 00:30:48,546 --> 00:30:53,006 and assemble on shorter turf, for they are about to start their spring dances. 244 00:31:14,539 --> 00:31:18,635 Each male stays on a small patch of ground that is his dancing stage, 245 00:31:18,810 --> 00:31:24,908 and there erects his feathery horns, inflates his wattles and starts his stamping dance. 246 00:32:13,798 --> 00:32:17,393 The prairie dogs live in such concentrations and such numbers 247 00:32:17,568 --> 00:32:20,765 that their patch of the prairie is called a town. 248 00:32:21,372 --> 00:32:23,966 They mated below ground back in February. 249 00:32:24,208 --> 00:32:28,338 The youngsters were born a month later and now, in the sunshine of early summer, 250 00:32:28,579 --> 00:32:30,308 they get their first view of the world. 251 00:32:54,539 --> 00:32:56,473 The bison, too, have their young. 252 00:32:56,708 --> 00:33:00,804 The thick woollen coat that protected them through the winter is now far too hot, 253 00:33:01,045 --> 00:33:03,912 and the animals begin to shed it in sheets and tatters. 254 00:33:12,824 --> 00:33:17,693 The bison, being such a big animal, has a long gestation period, nine months. 255 00:33:17,929 --> 00:33:21,330 So, soon after the young are born, courting starts again, 256 00:33:21,599 --> 00:33:24,397 and for the bulls that involves battling with rivals. 257 00:33:24,902 --> 00:33:28,804 These jousts, which can be very punishing and even end in death, 258 00:33:29,007 --> 00:33:31,567 establish a ranking among the bulls. 259 00:33:34,345 --> 00:33:38,679 The victors can then seek access to the cows, which is another problem. 260 00:34:11,983 --> 00:34:16,977 The bison herds have a particular liking for the grazing around the prairie dogs' towns, 261 00:34:17,155 --> 00:34:19,248 for the prairie dogs are good farmers. 262 00:34:19,490 --> 00:34:23,950 They deliberately cut down unpalatable plants and remove dead material, 263 00:34:24,128 --> 00:34:28,155 and their constant cropping means that the grass leaves around their burrows 264 00:34:28,332 --> 00:34:30,857 are all young and succulent, and the bison like that 265 00:34:31,035 --> 00:34:32,969 just as much as the prairie dogs do. 266 00:34:47,285 --> 00:34:52,188 The rattlesnakes also haunt the town, on the lookout for young prairie dogs. 267 00:34:52,490 --> 00:34:57,951 The shortness of the cropped turf makes it easy for the town sentinels to see approaching danger. 268 00:35:09,674 --> 00:35:12,006 What to do about it is another question. 269 00:35:30,027 --> 00:35:32,860 Bolting down a burrow is no defence against a rattlesnake. 270 00:35:33,030 --> 00:35:38,832 It will simply follow. The only thing to do is ret and whistle a warning to the neighbours. 271 00:35:47,345 --> 00:35:50,974 Bison are cattle. Like antelope and sheep, they are ruminants, 272 00:35:51,215 --> 00:35:56,175 dealing with the problem of digesting cellulose by regurgitating pellets of grass they graze 273 00:35:56,354 --> 00:35:58,345 and giving it all a second chew. 274 00:35:58,856 --> 00:36:03,350 They also maintain a digestive broth of bacteria in their huge stomachs. 275 00:36:03,661 --> 00:36:07,654 Only 150 years ago, they lived in such numbers on the prairies 276 00:36:07,899 --> 00:36:10,629 that a herd could stretch from one horizon to another. 277 00:36:11,269 --> 00:36:15,968 How many there were altogether is uncertain. Thirty million is one of the lower estimates. 278 00:36:16,207 --> 00:36:19,802 That was a measure of the great fertility of these natural grasslands. 279 00:36:20,578 --> 00:36:25,447 Today, most of the prairie has been turned over to the raising of domesticated cattle for beef, 280 00:36:25,616 --> 00:36:29,279 or ploughed up to grow domesticated grass, wheat. 281 00:36:29,987 --> 00:36:33,946 By the beginning of this century, less than a thousand wild bison were left. 282 00:36:34,125 --> 00:36:40,291 But today, thanks to careful conservation, there are some 35,000 living in reserves. 283 00:36:41,399 --> 00:36:46,735 The prairies receive comparatively little rain because they lie in the centre of a huge continent 284 00:36:46,904 --> 00:36:49,998 and the Rocky Mountains screen off the rain. 285 00:36:54,278 --> 00:36:58,112 Across the northern Pacific, the biggest continental mass of all, Eurasia, 286 00:36:58,282 --> 00:37:02,776 also contains a heartland where relatively little rain falls - 287 00:37:02,954 --> 00:37:06,048 the grass-covered steppes of Russia and Eastern Europe. 288 00:37:06,290 --> 00:37:11,125 And here another grass feeder survives that once formed vast herds, 289 00:37:11,362 --> 00:37:14,092 an extraordinary antelope, the saiga. 290 00:37:18,135 --> 00:37:22,128 Its huge nose contains, internally, a convoluted arrangement of passages 291 00:37:22,306 --> 00:37:26,140 lined with mucous glands that apparently serve to warm and moisten 292 00:37:26,310 --> 00:37:29,177 the dry air of the steppes and filter out the dust 293 00:37:39,323 --> 00:37:41,257 The steppes are not as fertile as the prairie 294 00:37:41,425 --> 00:37:44,656 and are ravaged by regular and disastrous droughts. 295 00:37:45,029 --> 00:37:49,762 But the saiga seem to have adapted to this and have a quite extraordinary rate of reproduction 296 00:37:49,934 --> 00:37:54,303 that enables them to recover their numbers after such a catastrophe with great speed. 297 00:37:54,872 --> 00:37:59,275 The females, when they are a mere four months old and only half-grown, 298 00:37:59,443 --> 00:38:01,911 mate and produce their first calf. 299 00:38:02,413 --> 00:38:06,747 After it is weaned, they grow rapidly, so that by the beginning of the next breeding season, 300 00:38:06,917 --> 00:38:10,944 they are full-size, and then they quickly breed again - and this time 301 00:38:11,122 --> 00:38:13,647 three quarters of them will produce twins. 302 00:38:15,226 --> 00:38:17,786 These animals, too, were hunted close to extinction, 303 00:38:17,995 --> 00:38:21,123 but when people realised that these natural inhabitants of the steppes 304 00:38:21,299 --> 00:38:25,360 could turn their grass into meat much more efficiently than any domesticated animal, 305 00:38:25,636 --> 00:38:31,040 indiscriminate hunting was stopped and now there are over two million in the Soviet Union. 306 00:38:33,511 --> 00:38:38,312 Travel south west from the steppes of central Eurasia, the greatest of all temperate grasslands, 307 00:38:38,549 --> 00:38:42,383 across territory where there is so little rain that not even grass can grow, 308 00:38:42,620 --> 00:38:47,216 and you come to the greatest of all tropical grasslands - in Africa. 309 00:38:55,333 --> 00:38:58,234 Here there is enough rain to create rivers and waterholes, 310 00:38:58,469 --> 00:39:03,998 so in the moist soils around them and on rocky outcrops, a few trees manage to grow. 311 00:39:06,243 --> 00:39:10,771 In the more regularly watered parts, thorn trees stand, distanced from one another, 312 00:39:11,015 --> 00:39:15,475 their widespread root-systems managing to collectjust enough water to sustain them. 313 00:39:16,053 --> 00:39:18,715 Elsewhere, there is only enough rainfall for grass 314 00:39:20,691 --> 00:39:23,922 But young trees are threatened not only by drought but by fire. 315 00:39:24,328 --> 00:39:27,456 It sweeps rapidly over the plains, killing the tree seedlings 316 00:39:27,631 --> 00:39:32,193 but leaving the growing buds of the grasses, close to the ground, quite unharmed, 317 00:39:32,503 --> 00:39:35,336 and green shoots of grass appear within days. 318 00:39:35,539 --> 00:39:39,134 So the fire, which starts so easily in withered grass stems, 319 00:39:39,377 --> 00:39:43,143 is one of the factors that keeps the country open, for grass. 320 00:39:46,384 --> 00:39:52,118 The grasslands of Africa stretch in an immense and almost continuous arc 321 00:39:52,289 --> 00:39:56,851 from the Sahara in the north down through East Africa 322 00:39:57,061 --> 00:40:01,498 and on to the great game plains of Southern Africa and the Cape. 323 00:40:01,732 --> 00:40:07,932 During the eight million years or so of recent history, they've varied quite a lot in their exten 324 00:40:08,105 --> 00:40:11,768 At the moment, they are not as big as they have been in the past. 325 00:40:11,942 --> 00:40:17,380 But during this period of time, the grasslands have developed, and as they have done so, 326 00:40:17,548 --> 00:40:20,039 the animals that lived on them have evolved, 327 00:40:20,251 --> 00:40:23,277 the nature of one reacting on the nature of the other. 328 00:40:23,454 --> 00:40:28,858 Today, there's a greater variety and a bigger concentration of grass-living creatures 329 00:40:29,026 --> 00:40:32,427 on these African plains than anywhere else in the world. 330 00:40:46,143 --> 00:40:50,239 Different lengths of neck, different sets of teeth, different appetites, 331 00:40:50,414 --> 00:40:55,078 such variety means that almost every growing leaf, short or long, 332 00:40:55,286 --> 00:40:59,188 of every kind of plains plant, is eaten by something. 333 00:41:10,568 --> 00:41:14,470 This vast tonnage of meat on the hoof has led, inevitably, 334 00:41:14,638 --> 00:41:18,005 to the appearance of an abundance of meat-eaters. 335 00:41:19,977 --> 00:41:23,640 And they too are varied, to exploit the variety of meat available. 336 00:41:25,416 --> 00:41:27,475 The serval seeks mice. 337 00:41:43,667 --> 00:41:48,161 The lions, hunting in teams, butcher wildebeest and zebra. 338 00:41:51,976 --> 00:41:53,807 Hunting dogs do the same. 339 00:41:57,381 --> 00:42:00,873 The cheetah goes for animals its own size, gazelle. 340 00:42:28,612 --> 00:42:32,275 Before grass spread over the plains, the ancestors of grazing antelopes 341 00:42:32,449 --> 00:42:36,010 must have lived in bush country, rather as dik-dik do today. 342 00:42:36,654 --> 00:42:39,282 The bushes don't produce many leaves, but they are highly nutritious 343 00:42:39,456 --> 00:42:43,825 and there are enough in an acre or so to sustain a pair of these tiny antelope. 344 00:42:44,194 --> 00:42:48,221 So the dik-dik mate for life and are permanent residents of their territory. 345 00:42:48,599 --> 00:42:52,000 They know it intimately and have their own trails and hiding places, 346 00:42:52,169 --> 00:42:55,104 and they mark out its frontiers with special notices. 347 00:42:56,840 --> 00:43:00,799 The ritual is nearly always the same. The female visits the midden first. 348 00:43:02,179 --> 00:43:06,673 The buck is stimulated to follow and habitually goes through exactly the same sequence 349 00:43:06,850 --> 00:43:10,581 of smelling, urinating, scratching and dunging. 350 00:43:31,175 --> 00:43:35,942 When the ceremony is over, the buck marks the nearby bushes with a sticky perfumed wax 351 00:43:36,113 --> 00:43:38,172 from a gland just below his eyes. 352 00:43:42,286 --> 00:43:47,918 Impala, however, live in more open country and feed not only on bushes but on grass. 353 00:43:48,158 --> 00:43:52,424 Here they can't hide and they find their safety in numbers. 354 00:43:52,796 --> 00:43:56,357 With so many sharp eyes and acute ears, it's very difficult for a hunter 355 00:43:56,533 --> 00:43:58,296 to approach them undetected. 356 00:43:58,836 --> 00:44:02,135 But such a lifestyle obviously makes it impossible for the animals to live 357 00:44:02,306 --> 00:44:06,003 in permanent pairs on their own territory as the dik-dik do. 358 00:44:06,477 --> 00:44:09,537 Instead, the males and females form separate herds. 359 00:44:10,280 --> 00:44:12,475 The bucks then battle among themselves. 360 00:44:12,850 --> 00:44:17,719 Those that win will leave the bachelor herds and set up individual territories. 361 00:44:28,365 --> 00:44:33,132 When the victors have established themselves, the does visit them, one after the other. 362 00:44:33,370 --> 00:44:39,104 It is a very exhausting business for the bucks, repeatedly mating and fighting off challengers. 363 00:45:00,698 --> 00:45:04,964 After about three months of this, the once dominant bucks are worn out. 364 00:45:05,202 --> 00:45:10,139 They yield to other, fresher males and return to the bachelor herd to recover. 365 00:45:15,345 --> 00:45:17,779 Wildebeest live on grass alone. 366 00:45:17,981 --> 00:45:20,882 But the patchy distribution of rain over the African plains 367 00:45:21,051 --> 00:45:24,885 means that they can't stay permanently in the same place. 368 00:45:25,456 --> 00:45:30,086 They quickly exhaust pasture on one patch of the plains and must move to an area 369 00:45:30,260 --> 00:45:33,957 where rain has recently fallen and the grass is springing again. 370 00:45:34,364 --> 00:45:38,733 So the wildebeest are constantly on the move and their social arrangements 371 00:45:38,902 --> 00:45:42,133 have to be different from the dik-dik and impala. 372 00:45:42,506 --> 00:45:48,240 During the short breeding season, the males set up small territories along the migration routes. 373 00:45:48,512 --> 00:45:52,573 They advertise their pretensions by prancing around and snorting, 374 00:45:52,750 --> 00:45:59,451 seeking showy contests with rivals to demonstrate their virility to passing females. 375 00:46:08,999 --> 00:46:11,832 The problem then is to keep the females in their territory 376 00:46:12,002 --> 00:46:15,529 and prevent them from moving on to a rival's patch. 377 00:46:32,656 --> 00:46:35,648 The young calves, born only a few months before, 378 00:46:35,826 --> 00:46:42,527 adopt very early the jaunty, slightly crazy way of carrying on affected by their fathers. 379 00:47:01,985 --> 00:47:06,081 Within two weeks, the majority of the females are mated. 380 00:47:11,628 --> 00:47:18,397 And then, suddenly, almost overnight, the whole herd, hundreds of thousands strong, vanishes. 381 00:47:18,936 --> 00:47:21,302 They've gone in search of fresh pastures. 382 00:47:23,440 --> 00:47:28,935 The varying growth of the grass over the year affects the lives of people as well as animals. 383 00:47:29,313 --> 00:47:31,804 In the eastern part of the grasslands, in the Sudan, 384 00:47:31,982 --> 00:47:34,974 the people keep herds of semi-domesticated cattle. 385 00:47:35,686 --> 00:47:39,213 These are their pride and their wealth and their livelihood. 386 00:47:41,925 --> 00:47:47,830 At night they pen them in enclosures made from uprooted thorn bush, to keep out lion. 387 00:47:52,169 --> 00:47:57,072 The people can't settle in permanent villages, for their cattle exhaust the meagre pasture, 388 00:47:57,241 --> 00:48:01,940 just as wildebeest do, so periodically they too have to move. 389 00:48:02,346 --> 00:48:05,907 It is a nice question as to whether the animals are being driven by the people 390 00:48:06,083 --> 00:48:10,019 or whether the people are, willy-nilly, following the herds. 391 00:48:14,658 --> 00:48:20,324 Many people in the Sudan regard not only their semi-wild cattle as their own personal property, 392 00:48:20,497 --> 00:48:25,457 but also the fully wild game that regularly passes through their territory. 393 00:48:26,937 --> 00:48:31,670 The white-eared kob, the males black and white, the females a delicate tan, 394 00:48:31,842 --> 00:48:33,639 live in the southern Sudan. 395 00:48:34,344 --> 00:48:37,939 Here, during the rainy season, the does give birth to their young. 396 00:48:39,750 --> 00:48:44,813 As the rains end and the plains begin to dry out, the herds begin to move north, 397 00:48:45,022 --> 00:48:48,890 following the new flush of grass that springs from the receding waters. 398 00:48:51,795 --> 00:48:53,888 As they go, the herds are funnelled together 399 00:48:54,064 --> 00:48:59,525 by two rivers that flow closer and closer to one another until eventually they join 400 00:48:59,703 --> 00:49:03,161 and the kob have no alternative but to attempt to cross - 401 00:49:03,340 --> 00:49:06,673 and here the Merle people await them. 402 00:49:11,682 --> 00:49:15,914 For the Merle, this is an annual bonanza and a great celebration. 403 00:49:16,086 --> 00:49:19,317 Families have travelled from all over the tribal territory to take part 404 00:49:19,489 --> 00:49:21,980 and to claim their share in their harvest of meat. 405 00:49:22,359 --> 00:49:27,023 If all goes well, there will be great feasting. But that's by no means a certainty. 406 00:49:27,230 --> 00:49:30,666 If the herds don't appear, there will be real hunger in the tribe. 407 00:49:39,676 --> 00:49:43,635 In the early morning, the hunters cross the river to set up their ambush. 408 00:49:44,014 --> 00:49:46,380 There's no guarantee that the kob will come this way. 409 00:49:46,683 --> 00:49:51,143 If the rivers are low, they may well try to cross on a much broader front upstream. 410 00:50:22,619 --> 00:50:26,612 For the kob now, there is no going back. They have to cross. 411 00:50:54,851 --> 00:50:59,720 Day after day, the kob that have arrived at this crossing attempt to run the gauntlet. 412 00:51:44,634 --> 00:51:48,161 It takes several weeks for the whole migration to pass through. 413 00:51:49,372 --> 00:51:54,173 A million kob will make the journey. 5,000 of them will be killed. 414 00:51:54,644 --> 00:51:56,441 The Merle not only feast well now, 415 00:51:56,613 --> 00:52:01,710 they sun-dry the meat so that the families will have full stomachs for many months to come. 416 00:52:12,629 --> 00:52:18,625 In spite of the Merle's ambush, the vast majority of the kob reach the northern grasslands. 417 00:52:19,669 --> 00:52:24,504 There they will find enough food to sustain them throughout the critical months of the dry season. 418 00:52:24,674 --> 00:52:29,839 And there, too, they mate, so that next year herds will reappear to make the river crossing 419 00:52:30,013 --> 00:52:32,311 and provide the Merle, once more, with meat. 420 00:52:35,185 --> 00:52:37,153 And the grass, too, will spring again, 421 00:52:37,320 --> 00:52:43,657 this remarkable plant that can survive intense grazing and burning and flooding. 422 00:52:43,960 --> 00:52:46,793 The one thing it can't tolerate is drought. 423 00:52:47,097 --> 00:52:52,763 If there is just a little less rain, then its leaves wither, its roots shrivel 424 00:52:52,936 --> 00:52:56,565 and can no longer hold the soil together, so that the wind can catch it 425 00:52:56,740 --> 00:52:59,504 and blow away the small nutritious particles. 426 00:52:59,809 --> 00:53:05,008 And then it's reduced to little more than sand and the land becomes a desert. 427 00:53:05,382 --> 00:53:08,943 And it's to deserts that we're going in the next programme.