1 00:01:04,131 --> 00:01:08,465 These beautiful flowers belong to one of the most successful, 2 00:01:08,769 --> 00:01:11,567 the most widespread and the commonest of plants. 3 00:01:15,542 --> 00:01:19,000 There are about 10,000 species in this one family, 4 00:01:19,313 --> 00:01:23,443 and they claim over a quarter of all the vegetated land on earth. 5 00:01:23,817 --> 00:01:28,117 They are pollinated by the wind, they need far less water than most trees, 6 00:01:28,322 --> 00:01:33,624 and they can survive both burning and freezing. They are the grasses. 7 00:01:41,268 --> 00:01:45,500 These tough, persistent plants continue to grow even when they're trimmed 8 00:01:45,672 --> 00:01:48,800 day after day by grazing teeth. 9 00:01:50,177 --> 00:01:52,372 They are able to withstand all this rough treatment 10 00:01:52,546 --> 00:01:56,038 because the point from which a grass leaf grows is at its base 11 00:01:56,216 --> 00:01:59,049 close to the ground and is permanently active. 12 00:01:59,353 --> 00:02:05,087 So grass provides a continuous banquet for creatures big and small. 13 00:02:11,198 --> 00:02:15,658 Down among the tangled grass stems live not only creatures that eat grass 14 00:02:15,936 --> 00:02:18,996 but others that feed on the grass-eaters. 15 00:02:19,940 --> 00:02:25,435 Lizards snap up small insects and mantis munch grasshoppers. 16 00:02:36,757 --> 00:02:39,692 Spiders tackle almost any creature that moves 17 00:02:39,860 --> 00:02:43,261 and dung beetles clear up the droppings from above. 18 00:02:44,531 --> 00:02:48,763 Among the most industrious of these tiny labourers are the termites. 19 00:02:49,069 --> 00:02:53,699 On many tropical grasslands, they flourish in such numbers that, one way or another, 20 00:02:53,907 --> 00:02:59,368 they consume more of the grass than big creatures like antelope, cows or kangaroo. 21 00:03:03,750 --> 00:03:09,086 In Brazil's savannahs, there are more termite mounds per acre than anywhere in the world. 22 00:03:09,322 --> 00:03:11,222 And termites are highly nutritious - 23 00:03:11,491 --> 00:03:18,192 so much so that the giant anteater can exist by feeding on them and nothing else whatever. 24 00:03:23,070 --> 00:03:28,235 This creature has very poor eyesight and very poor hearing, 25 00:03:28,809 --> 00:03:34,748 and finds its way around mostly by smell, so, as long as I keep downwind of it, 26 00:03:34,948 --> 00:03:39,647 there's no reason why it should be particularly disturbed by my presence. 27 00:03:40,387 --> 00:03:43,481 You might think that that would make it very vulnerable to enemies. 28 00:03:43,824 --> 00:03:47,954 The fact is, out on the savannahs here, it's got very few enemies. 29 00:03:48,128 --> 00:03:54,761 The only things that might attack it are a jaguar or a puma, or if it was a baby, a savannah fox. 30 00:03:55,068 --> 00:03:58,936 And it has a very good defence against such creatures. 31 00:03:59,306 --> 00:04:05,336 Those huge forelegs, with enormous muscles on them and gigantic claws, 32 00:04:05,679 --> 00:04:11,743 are quite powerful enough to rip the stomach from a puma or a jaguar. 33 00:04:12,552 --> 00:04:18,582 It was always thought that those legs are actually for ripping open termite hills, 34 00:04:18,825 --> 00:04:22,386 and they may be used to some extent for that purpose. 35 00:04:22,562 --> 00:04:26,692 But it seems more likely now that they are primarily defensive weapons, 36 00:04:26,867 --> 00:04:28,858 because when they actually come to feed, 37 00:04:29,035 --> 00:04:32,562 this creature doesn't do so much of a sweep with its front claws 38 00:04:32,739 --> 00:04:39,144 as to use them very, very carefully to open the exit tunnels in the termite hills. 39 00:04:40,480 --> 00:04:43,916 Once it has done that, it pokes its nose into the tunnel entrance 40 00:04:44,084 --> 00:04:47,884 and flicks out its 20-inch-long tongue, coated with sticky mucus, 41 00:04:48,054 --> 00:04:52,081 and picks off the worker termites clinging to the tunnel walls. 42 00:04:58,832 --> 00:05:02,700 After about half a minute, before the soldier termites - which have powerful bites - 43 00:05:02,903 --> 00:05:07,272 can rally to the defence of the opened tunnel, the anteater moves on. 44 00:05:08,441 --> 00:05:12,468 It is a wanderer, always on the move, sleeping at night out in the open, 45 00:05:12,746 --> 00:05:16,512 blanketed against the cold by its huge hairy tail. 46 00:05:22,255 --> 00:05:27,158 Having no permanent den, the female carries her youngster with her, piggyback. 47 00:05:44,678 --> 00:05:48,114 Other termite hunters live on the surface of the mounds themselves. 48 00:05:48,381 --> 00:05:53,045 Beetle larvae lurk in burrows and lure flying ants and other insects to them 49 00:05:53,220 --> 00:05:55,711 by the luminous glow of their heads. 50 00:06:22,215 --> 00:06:26,618 Sometimes the termite mounds are attacked at their very foundations. 51 00:06:27,087 --> 00:06:30,545 This is the biggest insect-eater on earth, the giant armadillo, 52 00:06:30,724 --> 00:06:33,420 a massive animal that weighs over a hundredweight. 53 00:06:33,827 --> 00:06:35,419 There are few more powerful diggers. 54 00:06:35,762 --> 00:06:38,526 It's no finicky eater like the giant anteater, 55 00:06:38,698 --> 00:06:42,225 but rips its way through the ground into the heart of the termite hill. 56 00:06:46,573 --> 00:06:50,031 With its defences breached, the termite colony is very vulnerable. 57 00:06:50,410 --> 00:06:54,403 This mouse, oxymicterus, has a particular fondness for termites 58 00:06:54,581 --> 00:06:57,607 and regularly follows in the wake of the giant armadillo. 59 00:07:00,487 --> 00:07:03,251 But the termites' biggest enemies are even smaller. 60 00:07:04,324 --> 00:07:10,160 Carnivorous ants regularly raid the colonies, carrying off the helpless, pallid termite larvae. 61 00:07:11,798 --> 00:07:15,825 The defenders of the colony, the soldier termites, engage the enemy ants. 62 00:07:22,242 --> 00:07:25,439 These termite warriors have jaws so specialised for fighting 63 00:07:25,612 --> 00:07:29,548 that they can't feed for themselves and have to be tended by the workers. 64 00:07:30,784 --> 00:07:33,150 Each species is armed in its own way. 65 00:07:36,423 --> 00:07:39,483 Some have short nippers, some sharp shears. 66 00:07:39,726 --> 00:07:44,527 Others have blades that strike outwards and others nozzles on their forehead 67 00:07:44,698 --> 00:07:47,895 through which they squirt a sticky poison spray. 68 00:08:06,186 --> 00:08:08,984 Other ants are vegetarians, like the termites, 69 00:08:09,289 --> 00:08:14,124 and use theirjaws to demolish the living grass plants, scissoring up the leaves, 70 00:08:14,327 --> 00:08:17,819 sawing through the stems and carrying off the plant piecemeal. 71 00:08:22,102 --> 00:08:27,404 Grass consists largely of cellulose and that is a very difficult substance to digest. 72 00:08:27,674 --> 00:08:30,973 Termites do it with the help of bacteria in their gut. 73 00:08:31,444 --> 00:08:34,880 The grass-cutting ants have another and quite extraordinary method 74 00:08:35,048 --> 00:08:37,516 of making its nutriment digestible. 75 00:08:37,984 --> 00:08:40,953 Laboriously, they haul the pieces of grass back to their nest, 76 00:08:41,121 --> 00:08:46,024 which may be as much as 100 yards away and have several hundred small entrances. 77 00:08:48,561 --> 00:08:53,328 Inside an entrance, a tunnel leads down into a vast labyrinth of corridors 78 00:08:53,500 --> 00:08:57,561 that may extend for 80 or 90 feet in a horizontal direction 79 00:08:57,737 --> 00:09:01,798 and lead to as many as 2,000 interlinked chambers. 80 00:09:05,812 --> 00:09:10,340 Such a nest may contain as many as 20 million ants. 81 00:09:18,725 --> 00:09:22,627 The workers carry their cuttings deeper and deeper into the nest. 82 00:09:26,699 --> 00:09:31,636 And here, 15 feet below the surface of the ground, in special chambers, 83 00:09:31,905 --> 00:09:35,136 they feed the grass to a fungus. 84 00:09:35,975 --> 00:09:42,073 This fungus forms crumbly white lumps and grows nowhere else but in these nests. 85 00:09:44,484 --> 00:09:47,612 Carefully, the ant gardeners clean every fragment of grass. 86 00:09:47,821 --> 00:09:51,348 Meticulously, they remove every spore of any other fungus 87 00:09:51,524 --> 00:09:55,858 that might grow down here if it got the chance. Weeds, as you might say. 88 00:09:56,362 --> 00:09:59,490 The waxy skin that covers the leaf surface is stripped away 89 00:09:59,666 --> 00:10:03,466 and then the pieces are cut up into even smaller fragments. 90 00:10:09,442 --> 00:10:14,141 The gardeners push the prepared morsels of grass into the mass of the fungus. 91 00:10:14,414 --> 00:10:18,248 The fungus digests it, cellulose and all, and grows, 92 00:10:18,418 --> 00:10:23,981 and the ants then feed on the fungus, which, unlike grass, they can digest. 93 00:10:35,335 --> 00:10:38,065 The ants tend their gardens with great care. 94 00:10:38,371 --> 00:10:42,068 Dead pieces of fungus and coarse, unsuitable fragments of leaves 95 00:10:42,242 --> 00:10:45,177 are carefully removed and carried away. 96 00:10:51,651 --> 00:10:57,681 With unflagging energy, porter lines of ants carry the waste down the long corridors 97 00:10:57,857 --> 00:11:04,695 to the lowest chambers of all, 20 feet below ground, that serve as the colony's refuse tips. 98 00:11:16,643 --> 00:11:20,477 These are not only rubbish dumps, but cemeteries, 99 00:11:20,647 --> 00:11:24,606 for here they also bring the bodies of dead workers. 100 00:11:36,863 --> 00:11:41,323 Dawn on the grasslands of Brazil, the campo. 101 00:11:54,547 --> 00:11:57,516 It's still chilly and the dew lies heavily. 102 00:11:57,817 --> 00:12:03,255 But the rising sun will soon dry out the pasturage and rouse the daytime inhabitants. 103 00:12:29,482 --> 00:12:35,978 The grassland birds have no trees from which to sing. Some make do with grass stems. 104 00:12:36,623 --> 00:12:42,391 Others, like the scissor-tailed flycatcher, proclaim their territorial rights by visual displa 105 00:12:42,562 --> 00:12:46,999 flying incessantly and conspicuously above their chosen plots. 106 00:13:02,815 --> 00:13:09,653 The seriama, a catcher of snakes and insects, surveys the prospects from a termite hill. 107 00:13:11,157 --> 00:13:14,649 The tapir has browsed throughout the night, but now, as the sun rises, 108 00:13:14,827 --> 00:13:19,127 it makes its way back to the forest that grows in the moist ground beside the river, 109 00:13:19,299 --> 00:13:25,966 for it prefers that shady obscurity to the hot conspicuousness of the daytime plains. 110 00:13:31,844 --> 00:13:37,305 On the other hand, the savannah deer has slept all night and only grazes when it is lig 111 00:13:37,784 --> 00:13:40,048 It prefers to be able to see its enemies. 112 00:13:42,789 --> 00:13:47,920 The armadillo is no grass-eater. It's looking for insects, roots and birds' eggs, 113 00:13:48,094 --> 00:13:50,426 and even a lizard or a small snake. 114 00:13:56,169 --> 00:13:59,969 As the day warms up, reptiles become active. 115 00:14:03,810 --> 00:14:08,509 The tegu lizard is sufficiently powerful to be able to take on all-comers. 116 00:14:09,782 --> 00:14:16,585 Just what it likes, and no small bird, no matter how aggressive, is able to repel a hungry tegu. 117 00:14:30,470 --> 00:14:33,633 Eggs on the ground are very much at risk from creatures like this. 118 00:14:33,806 --> 00:14:37,572 But where else can you put them? There are few trees on the grassland. 119 00:14:38,111 --> 00:14:40,238 But there are termite hills. 120 00:14:44,851 --> 00:14:48,218 The flicker is a kind of woodpecker and drills into termite hills 121 00:14:48,388 --> 00:14:51,824 just as efficiently as its cousins do into tree trunks. 122 00:14:54,360 --> 00:14:58,763 And when the flicker has finished with its hole, kestrels often take it over. 123 00:15:04,904 --> 00:15:06,394 The male has a lizard. 124 00:15:06,639 --> 00:15:11,076 Softly, he summons the female, who is incubating her eggs in the hole beneath. 125 00:15:21,954 --> 00:15:24,855 The burrowing owls nest in holes in the ground, 126 00:15:25,024 --> 00:15:27,891 taking over ones that have been abandoned by armadillos 127 00:15:28,060 --> 00:15:30,358 or even digging them for themselves. 128 00:15:30,663 --> 00:15:35,566 The male perches on a termite hill on guard, for the chicks are about to emerge. 129 00:15:42,141 --> 00:15:43,802 Danger - a harrier. 130 00:15:55,988 --> 00:15:58,149 Now it's safe once more. 131 00:15:58,491 --> 00:16:04,430 As long as the chicks can't fly, they're in danger from armadillos, tegus and other predators. 132 00:16:04,697 --> 00:16:08,258 So it is very important that they get their flight feathers as quickly as possible, 133 00:16:08,434 --> 00:16:12,803 and already, only a couple of weeks after hatching, they are showing through the down. 134 00:16:21,747 --> 00:16:26,480 Out in the fresh air, there is space to preen and a chance to sunbathe. 135 00:16:57,717 --> 00:17:04,088 Once more there is an alarm... It's the spur-winged plovers. 136 00:17:14,600 --> 00:17:16,568 The plovers are quarrelsome birds. 137 00:17:16,736 --> 00:17:20,467 Even though each pair has established its claims over a patch of grassland, 138 00:17:20,640 --> 00:17:23,666 the birds continually dispute with their neighbours. 139 00:17:24,277 --> 00:17:28,179 Rivals display aggressively, running along the frontier between their territories 140 00:17:28,347 --> 00:17:30,338 and dive-bombing one another. 141 00:17:42,595 --> 00:17:46,497 Their nest is probably as safe as it would be even if they remained sitting on it, 142 00:17:46,766 --> 00:17:50,793 for their eggs are marvellously camouflaged and very difficult to see. 143 00:17:56,008 --> 00:18:00,638 The adult tinamou, on the other hand, is just as well-disguised as the plover's eggs. 144 00:18:01,047 --> 00:18:03,538 Its strategy is to stay put and freeze. 145 00:18:03,950 --> 00:18:08,444 Just as well, for its eggs are very conspicuous, a brilliant shiny purple. 146 00:18:13,292 --> 00:18:16,819 One ground-nester on the open plains, however, fears nothing. 147 00:18:17,063 --> 00:18:21,864 It's big enough and strong enough to take on even an armadillo or a tegu. 148 00:18:23,069 --> 00:18:25,765 The rhea, the South American ostrich. 149 00:18:28,007 --> 00:18:30,942 It's the male that makes the nest and incubates the eggs. 150 00:18:31,210 --> 00:18:36,546 And he is polygamous, with half a dozen or so females, all of whom will lay in his nest. 151 00:18:43,189 --> 00:18:47,956 But with so many contributors, the compiling of a clutch can be a tricky business. 152 00:18:48,361 --> 00:18:53,822 Sometimes several females, each with an egg ready to be laid, will turn up at the same time 153 00:18:54,000 --> 00:18:57,527 and there's some confusion as to who's going to have the first turn. 154 00:18:57,770 --> 00:19:00,864 He doesn't seem to want them to lay in the main clutch. 155 00:19:01,140 --> 00:19:06,339 Perhaps he's worried about them treading on his eggs, so they'll have to sit outside. 156 00:19:11,584 --> 00:19:13,575 The first female goes down. 157 00:19:27,433 --> 00:19:30,527 Once laid, the egg has to be brought in to join the rest of the clutch 158 00:19:30,703 --> 00:19:32,694 if he is to incubate it properly. 159 00:19:35,508 --> 00:19:37,942 Another female settles down to lay. 160 00:19:43,049 --> 00:19:45,517 And another egg joins his collection. 161 00:20:05,237 --> 00:20:08,764 His final clutch may be huge, up to 50 or so. 162 00:20:09,175 --> 00:20:13,339 They've come from many different females and been laid over a period of eight days, 163 00:20:13,512 --> 00:20:15,104 but all hatch together. 164 00:20:15,581 --> 00:20:19,039 The young pipe to one another while they're still inside their shells, 165 00:20:19,218 --> 00:20:24,087 stimulating the eggs that are a bit behind to speed up their development. 166 00:20:44,410 --> 00:20:48,870 The advantage of hatching simultaneously is that the young, soon after they emerge, 167 00:20:49,115 --> 00:20:52,607 can go off and feed together under Father's watchful eye. 168 00:21:25,951 --> 00:21:29,978 The open grassland is full of dangers and there are very few places to hide 169 00:21:30,156 --> 00:21:32,818 from the many enemies that lie in wait for the chicks. 170 00:21:33,359 --> 00:21:36,954 The maned wolf will certainly take one if it gets the chance. 171 00:21:41,433 --> 00:21:45,631 It hunts alone, never forming packs, seldom even seen with its mate. 172 00:21:45,871 --> 00:21:50,035 It maintains contact with others of its kind by an occasional bark 173 00:21:50,209 --> 00:21:55,203 and by leaving its scent on bushes and termite mounds, spraying its urine high up 174 00:21:55,447 --> 00:21:58,610 so that the wind will pick up the smell and broadcast it. 175 00:22:00,920 --> 00:22:07,018 This wolf's tastes are, oddly, strongly vegetarian. Fruit forms a large part of its diet. 176 00:22:30,649 --> 00:22:35,279 But it certainly takes birds if it can, and the tinamou is particularly vulnerable, 177 00:22:35,454 --> 00:22:37,115 for it's almost flightless. 178 00:23:22,935 --> 00:23:27,634 Trees don't grow on the open plains of Argentina and Brazil because, for much of the year, 179 00:23:27,806 --> 00:23:29,296 there is too little rain. 180 00:23:29,775 --> 00:23:34,178 During the dry season, the shallow lakes are reduced to stretches of baked mud. 181 00:23:34,380 --> 00:23:40,842 Capybara, giant semi-aquatic guinea pigs, crowd into the few shrinking pools that remain. 182 00:23:41,754 --> 00:23:44,746 Cayman are compelled to spend much of their time out of water, 183 00:23:44,924 --> 00:23:49,987 and turtles jostle for places along the contractin margins with the capybara. 184 00:23:52,564 --> 00:23:57,001 But during April, the clouds begin to gather and in June they burst. 185 00:24:08,614 --> 00:24:12,277 It's a testing time for many of the grassland creatures. 186 00:24:23,629 --> 00:24:29,625 2,000 miles north of the Brazilian campo, the grasslands of Venezuela, the llanos, 187 00:24:29,802 --> 00:24:34,705 flood over great areas, for the ground is full of clay and holds the water. 188 00:24:36,008 --> 00:24:38,408 For some, this is exactly what they want. 189 00:24:44,717 --> 00:24:49,211 The llanos are flooded like this for almost half the year. 190 00:24:49,488 --> 00:24:52,150 That's all right for those capybara. 191 00:24:52,458 --> 00:24:56,485 They are almost as much at home in the water as they are on land. 192 00:24:56,729 --> 00:25:01,029 Some creatures, even such an unlikely-looking swimmer as the giant anteater, 193 00:25:01,200 --> 00:25:03,532 manage to struggle to dry ground. 194 00:25:04,503 --> 00:25:07,495 The armadillo, too, is very competent in the water. 195 00:25:12,311 --> 00:25:16,907 Many others, such as burrowing rodents that might otherwise crop the grass of the plains, 196 00:25:17,082 --> 00:25:21,416 can't do so because they can't survive being flooded like this every year. 197 00:25:22,121 --> 00:25:26,421 The grass, however, grows tall and lives through even this hardship. 198 00:25:27,926 --> 00:25:33,296 2,000 miles farther north still, water lies on the plains for many months on end, 199 00:25:33,532 --> 00:25:36,797 as snow on the prairies of North America. 200 00:25:38,070 --> 00:25:42,370 Here the temperature can drop to 46 degrees below zero centigrade. 201 00:25:42,775 --> 00:25:46,871 The resistant grass survives it but few animals can. 202 00:25:48,480 --> 00:25:53,577 The ground squirrels retreat to their burrows and go into a state of suspended animation. 203 00:25:54,153 --> 00:25:58,453 Their temperature falls and their breathing rate slows - they hibernate, 204 00:25:58,757 --> 00:26:03,319 using the absolute minimum of their body reserves accumulated during the summer. 205 00:26:14,139 --> 00:26:17,768 A cousin of the ground squirrel, another rodent called the prairie dog, 206 00:26:18,043 --> 00:26:22,605 does remain active, and during milder spells it ventures out onto the snow 207 00:26:22,781 --> 00:26:24,510 to nibble what leaves it can find. 208 00:26:28,821 --> 00:26:33,952 The prairie chicken, actually a grouse, is one of the few birds to stay on the winter prairies, 209 00:26:34,126 --> 00:26:39,894 for although there are no insects to be had now, it can survive on nothing but seeds and leaves. 210 00:26:43,435 --> 00:26:46,768 Things are happening, however, below ground. 211 00:26:49,074 --> 00:26:51,872 The pocket gopher is still hard at work. 212 00:26:54,379 --> 00:26:57,644 Its winter food is roots, and very nourishing they are, 213 00:26:57,816 --> 00:27:01,582 for many plants in autumn withdraw much of their substance from withering leaves 214 00:27:01,753 --> 00:27:03,550 and store it in their roots. 215 00:27:09,361 --> 00:27:14,162 The bison manages to survive even the coldest weather out on the prairie. 216 00:27:14,399 --> 00:27:16,924 Big animals are not as easily chilled as small ones, 217 00:27:17,102 --> 00:27:20,503 and the bison is the most massive animal in North America. 218 00:27:20,906 --> 00:27:22,271 A bull can weigh a ton. 219 00:27:28,247 --> 00:27:32,240 The extreme temperatures have, in effect, put the grass into deep freeze, 220 00:27:32,518 --> 00:27:37,319 so that, although it's frozen solid, such nutriment as it contained is preserved. 221 00:27:37,956 --> 00:27:41,619 The bison, being so big, have no difficulty in sweeping away the snow 222 00:27:41,793 --> 00:27:43,852 and reaching the frozen tufts. 223 00:27:45,864 --> 00:27:49,595 Bison share the prairies with pronghorn antelope which, in winter, 224 00:27:49,768 --> 00:27:52,931 often visit areas that the bison have just cleared of snow. 225 00:27:53,372 --> 00:27:59,038 They are the swiftest animals in North America, capable of speeds of 50 mph at full stretch. 226 00:28:01,480 --> 00:28:06,975 Coyotes, a small relation of the wolf, have little chance of catching a young healthy pronghorn. 227 00:28:07,219 --> 00:28:10,711 But that doesn't mean they won't try, and by chasing, they can discover 228 00:28:10,889 --> 00:28:15,519 if there are any antelope in the group that are less than healthy and therefore catchable. 229 00:28:48,060 --> 00:28:50,085 Anotherjoins the chase. 230 00:29:02,274 --> 00:29:06,301 The bitter cold and the shortage of food kills many animals at this time. 231 00:29:06,511 --> 00:29:11,915 For the coyotes, a carcass is precious, a mass of meat in an otherwise barren land. 232 00:29:12,217 --> 00:29:15,550 A pair has already taken possession of this dead elk. 233 00:29:16,955 --> 00:29:19,446 A third arrives. There will be trouble. 234 00:29:24,863 --> 00:29:30,426 They signal their threats with bristling fur, snarling lips but surprisingly little sound. 235 00:30:05,904 --> 00:30:10,204 As spring approaches, the temperature rises, even below ground, 236 00:30:10,475 --> 00:30:13,069 and the winter sleepers begin to awake. 237 00:30:16,515 --> 00:30:21,612 Rattlesnakes, forced to take shelter from the cold frequently take over the deeper burrows 238 00:30:21,787 --> 00:30:25,188 made by prairie dogs and there, ten feet below ground, 239 00:30:25,357 --> 00:30:28,690 sit out the winter beyond the reach of the lethal frost. 240 00:30:29,227 --> 00:30:33,493 Sometimes as many as two or three hundred will share the same hole. 241 00:30:34,099 --> 00:30:38,695 As the spring sun warms the air, so they too slowly come to life. 242 00:30:44,242 --> 00:30:47,871 The prairie chickens leave the tall grass country where they spent the winter 243 00:30:48,046 --> 00:30:52,506 and assemble on shorter turf, for they are about to start their spring dances. 244 00:31:14,039 --> 00:31:18,135 Each male stays on a small patch of ground that is his dancing stage, 245 00:31:18,310 --> 00:31:24,408 and there erects his feathery horns, inflates his wattles and starts his stamping dance. 246 00:32:13,298 --> 00:32:16,893 The prairie dogs live in such concentrations and such numbers 247 00:32:17,068 --> 00:32:20,265 that their patch of the prairie is called a town. 248 00:32:20,872 --> 00:32:23,466 They mated below ground back in February. 249 00:32:23,708 --> 00:32:27,838 The youngsters were born a month later and now, in the sunshine of early summer, 250 00:32:28,079 --> 00:32:29,808 they get their first view of the world. 251 00:32:54,039 --> 00:32:55,973 The bison, too, have their young. 252 00:32:56,208 --> 00:33:00,304 The thick woollen coat that protected them through the winter is now far too hot, 253 00:33:00,545 --> 00:33:03,412 and the animals begin to shed it in sheets and tatters. 254 00:33:12,324 --> 00:33:17,193 The bison, being such a big animal, has a long gestation period, nine months. 255 00:33:17,429 --> 00:33:20,830 So, soon after the young are born, courting starts again, 256 00:33:21,099 --> 00:33:23,897 and for the bulls that involves battling with rivals. 257 00:33:24,402 --> 00:33:28,304 These jousts, which can be very punishing and even end in death, 258 00:33:28,507 --> 00:33:31,067 establish a ranking among the bulls. 259 00:33:33,845 --> 00:33:38,179 The victors can then seek access to the cows, which is another problem. 260 00:34:11,483 --> 00:34:16,477 The bison herds have a particular liking for the grazing around the prairie dogs' towns, 261 00:34:16,655 --> 00:34:18,748 for the prairie dogs are good farmers. 262 00:34:18,990 --> 00:34:23,450 They deliberately cut down unpalatable plants and remove dead material, 263 00:34:23,628 --> 00:34:27,655 and their constant cropping means that the grass leaves around their burrows 264 00:34:27,832 --> 00:34:30,357 are all young and succulent, and the bison like that 265 00:34:30,535 --> 00:34:32,469 just as much as the prairie dogs do. 266 00:34:46,785 --> 00:34:51,688 The rattlesnakes also haunt the town, on the lookout for young prairie dogs. 267 00:34:51,990 --> 00:34:57,451 The shortness of the cropped turf makes it easy for the town sentinels to see approaching danger. 268 00:35:09,174 --> 00:35:11,506 What to do about it is another question. 269 00:35:29,527 --> 00:35:32,360 Bolting down a burrow is no defence against a rattlesnake. 270 00:35:32,530 --> 00:35:38,332 It will simply follow. The only thing to do is ret and whistle a warning to the neighbours. 271 00:35:46,845 --> 00:35:50,474 Bison are cattle. Like antelope and sheep, they are ruminants, 272 00:35:50,715 --> 00:35:55,675 dealing with the problem of digesting cellulose by regurgitating pellets of grass they graze 273 00:35:55,854 --> 00:35:57,845 and giving it all a second chew. 274 00:35:58,356 --> 00:36:02,850 They also maintain a digestive broth of bacteria in their huge stomachs. 275 00:36:03,161 --> 00:36:07,154 Only 150 years ago, they lived in such numbers on the prairies 276 00:36:07,399 --> 00:36:10,129 that a herd could stretch from one horizon to another. 277 00:36:10,769 --> 00:36:15,468 How many there were altogether is uncertain. Thirty million is one of the lower estimates. 278 00:36:15,707 --> 00:36:19,302 That was a measure of the great fertility of these natural grasslands. 279 00:36:20,078 --> 00:36:24,947 Today, most of the prairie has been turned over to the raising of domesticated cattle for beef, 280 00:36:25,116 --> 00:36:28,779 or ploughed up to grow domesticated grass, wheat. 281 00:36:29,487 --> 00:36:33,446 By the beginning of this century, less than a thousand wild bison were left. 282 00:36:33,625 --> 00:36:39,791 But today, thanks to careful conservation, there are some 35,000 living in reserves. 283 00:36:40,899 --> 00:36:46,235 The prairies receive comparatively little rain because they lie in the centre of a huge continent 284 00:36:46,404 --> 00:36:49,498 and the Rocky Mountains screen off the rain. 285 00:36:53,778 --> 00:36:57,612 Across the northern Pacific, the biggest continental mass of all, Eurasia, 286 00:36:57,782 --> 00:37:02,276 also contains a heartland where relatively little rain falls - 287 00:37:02,454 --> 00:37:05,548 the grass-covered steppes of Russia and Eastern Europe. 288 00:37:05,790 --> 00:37:10,625 And here another grass feeder survives that once formed vast herds, 289 00:37:10,862 --> 00:37:13,592 an extraordinary antelope, the saiga. 290 00:37:17,635 --> 00:37:21,628 Its huge nose contains, internally, a convoluted arrangement of passages 291 00:37:21,806 --> 00:37:25,640 lined with mucous glands that apparently serve to warm and moisten 292 00:37:25,810 --> 00:37:28,677 the dry air of the steppes and filter out the dust 293 00:37:38,823 --> 00:37:40,757 The steppes are not as fertile as the prairie 294 00:37:40,925 --> 00:37:44,156 and are ravaged by regular and disastrous droughts. 295 00:37:44,529 --> 00:37:49,262 But the saiga seem to have adapted to this and have a quite extraordinary rate of reproduction 296 00:37:49,434 --> 00:37:53,803 that enables them to recover their numbers after such a catastrophe with great speed. 297 00:37:54,372 --> 00:37:58,775 The females, when they are a mere four months old and only half-grown, 298 00:37:58,943 --> 00:38:01,411 mate and produce their first calf. 299 00:38:01,913 --> 00:38:06,247 After it is weaned, they grow rapidly, so that by the beginning of the next breeding season, 300 00:38:06,417 --> 00:38:10,444 they are full-size, and then they quickly breed again - and this time 301 00:38:10,622 --> 00:38:13,147 three quarters of them will produce twins. 302 00:38:14,726 --> 00:38:17,286 These animals, too, were hunted close to extinction, 303 00:38:17,495 --> 00:38:20,623 but when people realised that these natural inhabitants of the steppes 304 00:38:20,799 --> 00:38:24,860 could turn their grass into meat much more efficiently than any domesticated animal, 305 00:38:25,136 --> 00:38:30,540 indiscriminate hunting was stopped and now there are over two million in the Soviet Union. 306 00:38:33,011 --> 00:38:37,812 Travel south west from the steppes of central Eurasia, the greatest of all temperate grasslands, 307 00:38:38,049 --> 00:38:41,883 across territory where there is so little rain that not even grass can grow, 308 00:38:42,120 --> 00:38:46,716 and you come to the greatest of all tropical grasslands - in Africa. 309 00:38:54,833 --> 00:38:57,734 Here there is enough rain to create rivers and waterholes, 310 00:38:57,969 --> 00:39:03,498 so in the moist soils around them and on rocky outcrops, a few trees manage to grow. 311 00:39:05,743 --> 00:39:10,271 In the more regularly watered parts, thorn trees stand, distanced from one another, 312 00:39:10,515 --> 00:39:14,975 their widespread root-systems managing to collectjust enough water to sustain them. 313 00:39:15,553 --> 00:39:18,215 Elsewhere, there is only enough rainfall for grass 314 00:39:20,191 --> 00:39:23,422 But young trees are threatened not only by drought but by fire. 315 00:39:23,828 --> 00:39:26,956 It sweeps rapidly over the plains, killing the tree seedlings 316 00:39:27,131 --> 00:39:31,693 but leaving the growing buds of the grasses, close to the ground, quite unharmed, 317 00:39:32,003 --> 00:39:34,836 and green shoots of grass appear within days. 318 00:39:35,039 --> 00:39:38,634 So the fire, which starts so easily in withered grass stems, 319 00:39:38,877 --> 00:39:42,643 is one of the factors that keeps the country open, for grass. 320 00:39:45,884 --> 00:39:51,618 The grasslands of Africa stretch in an immense and almost continuous arc 321 00:39:51,789 --> 00:39:56,351 from the Sahara in the north down through East Africa 322 00:39:56,561 --> 00:40:00,998 and on to the great game plains of Southern Africa and the Cape. 323 00:40:01,232 --> 00:40:07,432 During the eight million years or so of recent history, they've varied quite a lot in their exten 324 00:40:07,605 --> 00:40:11,268 At the moment, they are not as big as they have been in the past. 325 00:40:11,442 --> 00:40:16,880 But during this period of time, the grasslands have developed, and as they have done so, 326 00:40:17,048 --> 00:40:19,539 the animals that lived on them have evolved, 327 00:40:19,751 --> 00:40:22,777 the nature of one reacting on the nature of the other. 328 00:40:22,954 --> 00:40:28,358 Today, there's a greater variety and a bigger concentration of grass-living creatures 329 00:40:28,526 --> 00:40:31,927 on these African plains than anywhere else in the world. 330 00:40:45,643 --> 00:40:49,739 Different lengths of neck, different sets of teeth, different appetites, 331 00:40:49,914 --> 00:40:54,578 such variety means that almost every growing leaf, short or long, 332 00:40:54,786 --> 00:40:58,688 of every kind of plains plant, is eaten by something. 333 00:41:10,068 --> 00:41:13,970 This vast tonnage of meat on the hoof has led, inevitably, 334 00:41:14,138 --> 00:41:17,505 to the appearance of an abundance of meat-eaters. 335 00:41:19,477 --> 00:41:23,140 And they too are varied, to exploit the variety of meat available. 336 00:41:24,916 --> 00:41:26,975 The serval seeks mice. 337 00:41:43,167 --> 00:41:47,661 The lions, hunting in teams, butcher wildebeest and zebra. 338 00:41:51,476 --> 00:41:53,307 Hunting dogs do the same. 339 00:41:56,881 --> 00:42:00,373 The cheetah goes for animals its own size, gazelle. 340 00:42:28,112 --> 00:42:31,775 Before grass spread over the plains, the ancestors of grazing antelopes 341 00:42:31,949 --> 00:42:35,510 must have lived in bush country, rather as dik-dik do today. 342 00:42:36,154 --> 00:42:38,782 The bushes don't produce many leaves, but they are highly nutritious 343 00:42:38,956 --> 00:42:43,325 and there are enough in an acre or so to sustain a pair of these tiny antelope. 344 00:42:43,694 --> 00:42:47,721 So the dik-dik mate for life and are permanent residents of their territory. 345 00:42:48,099 --> 00:42:51,500 They know it intimately and have their own trails and hiding places, 346 00:42:51,669 --> 00:42:54,604 and they mark out its frontiers with special notices. 347 00:42:56,340 --> 00:43:00,299 The ritual is nearly always the same. The female visits the midden first. 348 00:43:01,679 --> 00:43:06,173 The buck is stimulated to follow and habitually goes through exactly the same sequence 349 00:43:06,350 --> 00:43:10,081 of smelling, urinating, scratching and dunging. 350 00:43:30,675 --> 00:43:35,442 When the ceremony is over, the buck marks the nearby bushes with a sticky perfumed wax 351 00:43:35,613 --> 00:43:37,672 from a gland just below his eyes. 352 00:43:41,786 --> 00:43:47,418 Impala, however, live in more open country and feed not only on bushes but on grass. 353 00:43:47,658 --> 00:43:51,924 Here they can't hide and they find their safety in numbers. 354 00:43:52,296 --> 00:43:55,857 With so many sharp eyes and acute ears, it's very difficult for a hunter 355 00:43:56,033 --> 00:43:57,796 to approach them undetected. 356 00:43:58,336 --> 00:44:01,635 But such a lifestyle obviously makes it impossible for the animals to live 357 00:44:01,806 --> 00:44:05,503 in permanent pairs on their own territory as the dik-dik do. 358 00:44:05,977 --> 00:44:09,037 Instead, the males and females form separate herds. 359 00:44:09,780 --> 00:44:11,975 The bucks then battle among themselves. 360 00:44:12,350 --> 00:44:17,219 Those that win will leave the bachelor herds and set up individual territories. 361 00:44:27,865 --> 00:44:32,632 When the victors have established themselves, the does visit them, one after the other. 362 00:44:32,870 --> 00:44:38,604 It is a very exhausting business for the bucks, repeatedly mating and fighting off challengers. 363 00:45:00,198 --> 00:45:04,464 After about three months of this, the once dominant bucks are worn out. 364 00:45:04,702 --> 00:45:09,639 They yield to other, fresher males and return to the bachelor herd to recover. 365 00:45:14,845 --> 00:45:17,279 Wildebeest live on grass alone. 366 00:45:17,481 --> 00:45:20,382 But the patchy distribution of rain over the African plains 367 00:45:20,551 --> 00:45:24,385 means that they can't stay permanently in the same place. 368 00:45:24,956 --> 00:45:29,586 They quickly exhaust pasture on one patch of the plains and must move to an area 369 00:45:29,760 --> 00:45:33,457 where rain has recently fallen and the grass is springing again. 370 00:45:33,864 --> 00:45:38,233 So the wildebeest are constantly on the move and their social arrangements 371 00:45:38,402 --> 00:45:41,633 have to be different from the dik-dik and impala. 372 00:45:42,006 --> 00:45:47,740 During the short breeding season, the males set up small territories along the migration routes. 373 00:45:48,012 --> 00:45:52,073 They advertise their pretensions by prancing around and snorting, 374 00:45:52,250 --> 00:45:58,951 seeking showy contests with rivals to demonstrate their virility to passing females. 375 00:46:08,499 --> 00:46:11,332 The problem then is to keep the females in their territory 376 00:46:11,502 --> 00:46:15,029 and prevent them from moving on to a rival's patch. 377 00:46:32,156 --> 00:46:35,148 The young calves, born only a few months before, 378 00:46:35,326 --> 00:46:42,027 adopt very early the jaunty, slightly crazy way of carrying on affected by their fathers. 379 00:47:01,485 --> 00:47:05,581 Within two weeks, the majority of the females are mated. 380 00:47:11,128 --> 00:47:17,897 And then, suddenly, almost overnight, the whole herd, hundreds of thousands strong, vanishes. 381 00:47:18,436 --> 00:47:20,802 They've gone in search of fresh pastures. 382 00:47:22,940 --> 00:47:28,435 The varying growth of the grass over the year affects the lives of people as well as animals. 383 00:47:28,813 --> 00:47:31,304 In the eastern part of the grasslands, in the Sudan, 384 00:47:31,482 --> 00:47:34,474 the people keep herds of semi-domesticated cattle. 385 00:47:35,186 --> 00:47:38,713 These are their pride and their wealth and their livelihood. 386 00:47:41,425 --> 00:47:47,330 At night they pen them in enclosures made from uprooted thorn bush, to keep out lion. 387 00:47:51,669 --> 00:47:56,572 The people can't settle in permanent villages, for their cattle exhaust the meagre pasture, 388 00:47:56,741 --> 00:48:01,440 just as wildebeest do, so periodically they too have to move. 389 00:48:01,846 --> 00:48:05,407 It is a nice question as to whether the animals are being driven by the people 390 00:48:05,583 --> 00:48:09,519 or whether the people are, willy-nilly, following the herds. 391 00:48:14,158 --> 00:48:19,824 Many people in the Sudan regard not only their semi-wild cattle as their own personal property, 392 00:48:19,997 --> 00:48:24,957 but also the fully wild game that regularly passes through their territory. 393 00:48:26,437 --> 00:48:31,170 The white-eared kob, the males black and white, the females a delicate tan, 394 00:48:31,342 --> 00:48:33,139 live in the southern Sudan. 395 00:48:33,844 --> 00:48:37,439 Here, during the rainy season, the does give birth to their young. 396 00:48:39,250 --> 00:48:44,313 As the rains end and the plains begin to dry out, the herds begin to move north, 397 00:48:44,522 --> 00:48:48,390 following the new flush of grass that springs from the receding waters. 398 00:48:51,295 --> 00:48:53,388 As they go, the herds are funnelled together 399 00:48:53,564 --> 00:48:59,025 by two rivers that flow closer and closer to one another until eventually they join 400 00:48:59,203 --> 00:49:02,661 and the kob have no alternative but to attempt to cross - 401 00:49:02,840 --> 00:49:06,173 and here the Merle people await them. 402 00:49:11,182 --> 00:49:15,414 For the Merle, this is an annual bonanza and a great celebration. 403 00:49:15,586 --> 00:49:18,817 Families have travelled from all over the tribal territory to take part 404 00:49:18,989 --> 00:49:21,480 and to claim their share in their harvest of meat. 405 00:49:21,859 --> 00:49:26,523 If all goes well, there will be great feasting. But that's by no means a certainty. 406 00:49:26,730 --> 00:49:30,166 If the herds don't appear, there will be real hunger in the tribe. 407 00:49:39,176 --> 00:49:43,135 In the early morning, the hunters cross the river to set up their ambush. 408 00:49:43,514 --> 00:49:45,880 There's no guarantee that the kob will come this way. 409 00:49:46,183 --> 00:49:50,643 If the rivers are low, they may well try to cross on a much broader front upstream. 410 00:50:22,119 --> 00:50:26,112 For the kob now, there is no going back. They have to cross. 411 00:50:54,351 --> 00:50:59,220 Day after day, the kob that have arrived at this crossing attempt to run the gauntlet. 412 00:51:44,134 --> 00:51:47,661 It takes several weeks for the whole migration to pass through. 413 00:51:48,872 --> 00:51:53,673 A million kob will make the journey. 5,000 of them will be killed. 414 00:51:54,144 --> 00:51:55,941 The Merle not only feast well now, 415 00:51:56,113 --> 00:52:01,210 they sun-dry the meat so that the families will have full stomachs for many months to come. 416 00:52:12,129 --> 00:52:18,125 In spite of the Merle's ambush, the vast majority of the kob reach the northern grasslands. 417 00:52:19,169 --> 00:52:24,004 There they will find enough food to sustain them throughout the critical months of the dry season. 418 00:52:24,174 --> 00:52:29,339 And there, too, they mate, so that next year herds will reappear to make the river crossing 419 00:52:29,513 --> 00:52:31,811 and provide the Merle, once more, with meat. 420 00:52:34,685 --> 00:52:36,653 And the grass, too, will spring again, 421 00:52:36,820 --> 00:52:43,157 this remarkable plant that can survive intense grazing and burning and flooding. 422 00:52:43,460 --> 00:52:46,293 The one thing it can't tolerate is drought. 423 00:52:46,597 --> 00:52:52,263 If there is just a little less rain, then its leaves wither, its roots shrivel 424 00:52:52,436 --> 00:52:56,065 and can no longer hold the soil together, so that the wind can catch it 425 00:52:56,240 --> 00:52:59,004 and blow away the small nutritious particles. 426 00:52:59,309 --> 00:53:04,508 And then it's reduced to little more than sand and the land becomes a desert. 427 00:53:04,882 --> 00:53:08,443 And it's to deserts that we're going in the next programme.