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These beautiful flowers belong
to one of the most successful,
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00:00:38,000 --> 00:00:41,480
the most widespread
and the commonest of plants.
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00:00:44,960 --> 00:00:48,720
There are about 10,000 species
in this one family,
4
00:00:48,880 --> 00:00:52,880
and they claim over a quarter
of all the vegetated land on earth.
5
00:00:53,360 --> 00:00:57,640
They are pollinated by the wind,
they need far less water than most trees,
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00:00:57,800 --> 00:01:03,240
and they can survive both burning and freezing.
They are the grasses.
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00:01:10,480 --> 00:01:15,240
These tough, persistent plants continue to grow
even when they're trimmed
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00:01:15,400 --> 00:01:18,560
day after day by grazing teeth.
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00:01:19,520 --> 00:01:21,920
They are able to withstand
all this rough treatment
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00:01:22,080 --> 00:01:25,320
because the point from which
a grass leaf grows is at its base
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00:01:25,480 --> 00:01:28,520
close to the ground and is permanently active.
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00:01:29,040 --> 00:01:34,920
So grass provides a continuous banquet
for creatures big and small.
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00:01:40,560 --> 00:01:45,000
Down among the tangled grass stems
live not only creatures that eat grass
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00:01:45,160 --> 00:01:48,280
but others that feed on the grass-eaters.
15
00:01:49,360 --> 00:01:55,000
Lizards snap up small insects
and mantis munch grasshoppers.
16
00:02:06,240 --> 00:02:09,560
Spiders tackle almost
any creature that moves
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00:02:09,720 --> 00:02:13,000
and dung beetles clear up
the droppings from above.
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00:02:13,880 --> 00:02:18,400
Among the most industrious
of these tiny labourers are the termites.
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00:02:18,560 --> 00:02:23,000
On many tropical grasslands, they flourish
in such numbers that, one way or another,
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00:02:23,160 --> 00:02:28,920
they consume more of the grass than big
creatures like antelope, cows or kangaroo.
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00:02:33,160 --> 00:02:38,400
In Brazil's savannahs, there are more termite
mounds per acre than anywhere in the world.
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00:02:38,560 --> 00:02:41,040
And termites are highly nutritious -
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00:02:41,200 --> 00:02:48,240
so much so that the giant anteater can exist
by feeding on them and nothing else whatever.
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00:02:52,200 --> 00:02:57,560
This creature has very poor eyesight
and very poor hearing,
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00:02:57,720 --> 00:03:04,160
and finds its way around mostly by smell,
so, as long as I keep downwind of it,
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00:03:04,720 --> 00:03:09,320
there's no reason why it should be
particularly disturbed by my presence.
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00:03:09,840 --> 00:03:13,040
You might think that that would make it
very vulnerable to enemies.
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00:03:13,640 --> 00:03:17,560
The fact is, out on the savannahs here,
it's got very few enemies.
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00:03:17,720 --> 00:03:24,280
The only things that might attack it are a jaguar
or a puma, or if it was a baby, a savannah fox.
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00:03:24,440 --> 00:03:28,440
And it has a very good defence
against such creatures.
31
00:03:29,040 --> 00:03:34,840
Those huge forelegs, with enormous muscles
on them and gigantic claws,
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00:03:35,000 --> 00:03:41,360
are quite powerful enough to rip the stomach
from a puma or a jaguar.
33
00:03:42,320 --> 00:03:47,960
It was always thought that those legs
are actually for ripping open termite hills,
34
00:03:48,120 --> 00:03:51,720
and they may be used to some extent
for that purpose.
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00:03:51,880 --> 00:03:56,400
But it seems more likely now
that they are primarily defensive weapons,
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00:03:56,560 --> 00:03:58,600
because when they actually come to feed,
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00:03:58,760 --> 00:04:02,360
this creature doesn't do so much
of a sweep with its front claws
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00:04:02,520 --> 00:04:09,320
as to use them very, very carefully
to open the exit tunnels in the termite hills.
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00:04:09,920 --> 00:04:13,480
Once it has done that, it pokes its nose
into the tunnel entrance
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00:04:13,640 --> 00:04:17,680
and flicks out its 20-inch-long tongue,
coated with sticky mucus,
41
00:04:17,840 --> 00:04:21,600
and picks off the worker termites
clinging to the tunnel walls.
42
00:04:28,080 --> 00:04:32,320
After about half a minute, before the soldier
termites - which have powerful bites -
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00:04:32,480 --> 00:04:36,920
can rally to the defence of the opened tunnel,
the anteater moves on.
44
00:04:37,680 --> 00:04:42,080
It is a wanderer, always on the move,
sleeping at night out in the open,
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00:04:42,240 --> 00:04:45,960
blanketed against the cold by its huge hairy tail.
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00:04:51,640 --> 00:04:57,080
Having no permanent den, the female carries
her youngster with her, piggyback.
47
00:05:14,080 --> 00:05:17,840
Other termite hunters live on the surface
of the mounds themselves.
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00:05:18,000 --> 00:05:22,800
Beetle larvae lurk in burrows and lure flying ants
and other insects to them
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00:05:22,960 --> 00:05:25,200
by the luminous glow of their heads.
50
00:05:51,600 --> 00:05:56,120
Sometimes the termite mounds are attacked
at their very foundations.
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00:05:56,280 --> 00:06:00,280
This is the biggest insect-eater on earth,
the giant armadillo,
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00:06:00,440 --> 00:06:03,240
a massive animal that weighs
over a hundredweight.
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00:06:03,400 --> 00:06:05,400
There are few more powerful diggers.
54
00:06:05,560 --> 00:06:08,240
It's no finicky eater like the giant anteater,
55
00:06:08,400 --> 00:06:12,520
but rips its way through the ground
into the heart of the termite hill.
56
00:06:15,960 --> 00:06:19,640
With its defences breached,
the termite colony is very vulnerable.
57
00:06:19,800 --> 00:06:24,280
This mouse, oxymicterus,
has a particular fondness for termites
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00:06:24,440 --> 00:06:27,680
and regularly follows in the wake
of the giant armadillo.
59
00:06:29,880 --> 00:06:32,720
But the termites' biggest enemies
are even smaller.
60
00:06:33,720 --> 00:06:39,920
Carnivorous ants regularly raid the colonies,
carrying off the helpless, pallid termite larvae.
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00:06:41,200 --> 00:06:45,800
The defenders of the colony, the soldier termites,
engage the enemy ants.
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00:06:51,680 --> 00:06:55,440
These termite warriors have jaws
so specialised for fighting
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00:06:55,600 --> 00:06:59,480
that they can't feed for themselves
and have to be tended by the workers.
64
00:07:00,200 --> 00:07:02,880
Each species is armed in its own way.
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00:07:05,760 --> 00:07:09,160
Some have short nippers, some sharp shears.
66
00:07:09,320 --> 00:07:14,280
Others have blades that strike outwards
and others nozzles on their forehead
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00:07:14,440 --> 00:07:17,800
through which they squirt a sticky poison spray.
68
00:07:35,480 --> 00:07:38,640
Other ants are vegetarians, like the termites,
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00:07:38,800 --> 00:07:43,720
and use their jaws to demolish
the living grass plants, scissoring up the leaves,
70
00:07:43,880 --> 00:07:47,760
sawing through the stems
and carrying off the plant piecemeal.
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00:07:51,360 --> 00:07:56,880
Grass consists largely of cellulose
and that is a very difficult substance to digest.
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00:07:57,040 --> 00:08:00,440
Termites do it with the help
of bacteria in their gut.
73
00:08:01,000 --> 00:08:04,640
The grass-cutting ants have another
and quite extraordinary method
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00:08:04,800 --> 00:08:06,800
of making its nutriment digestible.
75
00:08:07,240 --> 00:08:10,720
Laboriously, they haul the pieces of grass
back to their nest,
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00:08:10,880 --> 00:08:15,760
which may be as much as 100 yards away
and have several hundred small entrances.
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00:08:17,880 --> 00:08:22,960
Inside an entrance, a tunnel leads down
into a vast labyrinth of corridors
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00:08:23,120 --> 00:08:27,320
that may extend for 80 or 90 feet
in a horizontal direction
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00:08:27,480 --> 00:08:31,320
and lead to as many
as 2,000 interlinked chambers.
80
00:08:35,160 --> 00:08:39,960
Such a nest may contain
as many as 20 million ants.
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00:08:48,200 --> 00:08:52,320
The workers carry their cuttings
deeper and deeper into the nest.
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00:08:56,160 --> 00:09:01,280
And here, 15 feet below the surface
of the ground, in special chambers,
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00:09:01,440 --> 00:09:04,920
they feed the grass to a fungus.
84
00:09:05,080 --> 00:09:11,120
This fungus forms crumbly white lumps
and grows nowhere else but in these nests.
85
00:09:13,840 --> 00:09:17,200
Carefully, the ant gardeners
clean every fragment of grass.
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00:09:17,360 --> 00:09:21,080
Meticulously, they remove every spore
of any other fungus
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00:09:21,240 --> 00:09:25,680
that might grow down here if it got the chance.
Weeds, as you might say.
88
00:09:25,840 --> 00:09:29,240
The waxy skin that covers the leaf surface
is stripped away
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00:09:29,400 --> 00:09:33,120
and then the pieces are cut up
into even smaller fragments.
90
00:09:38,960 --> 00:09:43,840
The gardeners push the prepared morsels
of grass into the mass of the fungus.
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00:09:44,000 --> 00:09:48,280
The fungus digests it,
cellulose and all, and grows,
92
00:09:48,440 --> 00:09:54,000
and the ants then feed on the fungus,
which, unlike grass, they can digest.
93
00:10:04,640 --> 00:10:07,720
The ants tend their gardens with great care.
94
00:10:07,880 --> 00:10:12,040
Dead pieces of fungus and coarse,
unsuitable fragments of leaves
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00:10:12,200 --> 00:10:15,080
are carefully removed and carried away.
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00:10:21,840 --> 00:10:27,440
With unflagging energy, porter lines of ants
carry the waste down the long corridors
97
00:10:27,600 --> 00:10:34,600
to the lowest chambers of all, 20 feet below
ground, that serve as the colony's refuse tips.
98
00:10:46,080 --> 00:10:50,040
These are not only rubbish dumps,
but cemeteries,
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00:10:50,200 --> 00:10:54,280
for here they also bring
the bodies of dead workers.
100
00:11:06,160 --> 00:11:10,560
Dawn on the grasslands of Brazil, the campo.
101
00:11:24,040 --> 00:11:27,120
It's still chilly and the dew lies heavily.
102
00:11:27,280 --> 00:11:33,080
But the rising sun will soon dry out the pasturage
and rouse the daytime inhabitants.
103
00:11:58,960 --> 00:12:05,200
The grassland birds have no trees from which
to sing. Some make do with grass stems.
104
00:12:06,080 --> 00:12:12,240
Others, like the scissor-tailed flycatcher,
proclaim their territorial rights by visual display,
105
00:12:12,400 --> 00:12:17,040
flying incessantly and conspicuously
above their chosen plots.
106
00:12:32,280 --> 00:12:38,720
The seriama, a catcher of snakes and insects,
surveys the prospects from a termite hill.
107
00:12:40,560 --> 00:12:44,720
The tapir has browsed throughout the night,
but now, as the sun rises,
108
00:12:44,880 --> 00:12:49,000
it makes its way back to the forest that grows
in the moist ground beside the river,
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00:12:49,160 --> 00:12:55,680
for it prefers that shady obscurity to the hot
conspicuousness of the daytime plains.
110
00:13:01,280 --> 00:13:07,040
On the other hand, the savannah deer
has slept all night and only grazes when it is light.
111
00:13:07,200 --> 00:13:09,760
It prefers to be able to see its enemies.
112
00:13:12,080 --> 00:13:17,560
The armadillo is no grass-eater.
It's looking for insects, roots and birds' eggs,
113
00:13:17,720 --> 00:13:20,240
and even a lizard or a small snake.
114
00:13:25,480 --> 00:13:29,760
As the day warms up, reptiles become active.
115
00:13:33,240 --> 00:13:37,880
The tegu lizard is sufficiently powerful
to be able to take on all-comers.
116
00:13:39,200 --> 00:13:46,200
Just what it likes, and no small bird, no matter
how aggressive, is able to repel a hungry tegu.
117
00:13:59,720 --> 00:14:03,400
Eggs on the ground are very much at risk
from creatures like this.
118
00:14:03,560 --> 00:14:07,040
But where else can you put them?
There are few trees on the grassland.
119
00:14:07,200 --> 00:14:10,160
But there are termite hills.
120
00:14:14,200 --> 00:14:17,800
The flicker is a kind of woodpecker
and drills into termite hills
121
00:14:17,960 --> 00:14:21,520
just as efficiently as its cousins do
into tree trunks.
122
00:14:23,720 --> 00:14:28,320
And when the flicker has finished with its hole,
kestrels often take it over.
123
00:14:34,280 --> 00:14:36,120
The male has a lizard.
124
00:14:36,280 --> 00:14:41,400
Softly, he summons the female,
who is incubating her eggs in the hole beneath.
125
00:14:51,320 --> 00:14:54,240
The burrowing owls nest in holes in the ground,
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00:14:54,400 --> 00:14:57,280
taking over ones that have been
abandoned by armadillos
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00:14:57,440 --> 00:15:00,040
or even digging them for themselves.
128
00:15:00,200 --> 00:15:05,120
The male perches on a termite hill on guard,
for the chicks are about to emerge.
129
00:15:11,440 --> 00:15:13,480
Danger - a harrier.
130
00:15:25,320 --> 00:15:27,800
Now it's safe once more.
131
00:15:27,960 --> 00:15:34,000
As long as the chicks can't fly, they're in danger
from armadillos, tegus and other predators.
132
00:15:34,160 --> 00:15:38,120
So it is very important that they get
their flight feathers as quickly as possible,
133
00:15:38,280 --> 00:15:42,720
and already, only a couple of weeks after
hatching, they are showing through the down.
134
00:15:51,080 --> 00:15:56,080
Out in the fresh air, there is space to preen
and a chance to sunbathe.
135
00:16:27,000 --> 00:16:33,320
Once more there is an alarm...
It's the spur-winged plovers.
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00:16:43,760 --> 00:16:46,000
The plovers are quarrelsome birds.
137
00:16:46,160 --> 00:16:50,200
Even though each pair has established
its claims over a patch of grassland,
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00:16:50,360 --> 00:16:53,680
the birds continually dispute
with their neighbours.
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00:16:53,840 --> 00:16:58,040
Rivals display aggressively, running along
the frontier between their territories
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00:16:58,200 --> 00:17:00,640
and dive-bombing one another.
141
00:17:00,800 --> 00:17:03,800
(CONSTANT SQUAWKING)
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00:17:11,960 --> 00:17:16,280
Their nest is probably as safe as it would be
even if they remained sitting on it,
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00:17:16,440 --> 00:17:20,440
for their eggs are marvellously camouflaged
and very difficult to see.
144
00:17:25,440 --> 00:17:30,440
The adult tinamou, on the other hand,
is just as well-disguised as the plover's eggs.
145
00:17:30,600 --> 00:17:32,840
Its strategy is to stay put and freeze.
146
00:17:33,320 --> 00:17:38,280
Just as well, for its eggs are very conspicuous,
a brilliant shiny purple.
147
00:17:42,480 --> 00:17:46,360
One ground-nester on the open plains,
however, fears nothing.
148
00:17:46,520 --> 00:17:51,440
It's big enough and strong enough
to take on even an armadillo or a tegu.
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00:17:52,320 --> 00:17:55,520
The rhea, the South American ostrich.
150
00:17:57,440 --> 00:18:00,680
It's the male that makes the nest
and incubates the eggs.
151
00:18:00,840 --> 00:18:06,120
And he is polygamous, with half a dozen
or so females, all of whom will lay in his nest.
152
00:18:12,520 --> 00:18:17,760
But with so many contributors, the compiling
of a clutch can be a tricky business.
153
00:18:17,920 --> 00:18:23,560
Sometimes several females, each with an egg
ready to be laid, will turn up at the same time
154
00:18:23,720 --> 00:18:27,080
and there's some confusion
as to who's going to have the first turn.
155
00:18:27,640 --> 00:18:30,440
He doesn't seem to want them
to lay in the main clutch.
156
00:18:30,600 --> 00:18:36,080
Perhaps he's worried about them treading
on his eggs, so they'll have to sit outside.
157
00:18:40,960 --> 00:18:43,360
The first female goes down.
158
00:18:56,720 --> 00:19:00,080
Once laid, the egg has to be brought in
to join the rest of the clutch
159
00:19:00,240 --> 00:19:02,560
if he is to incubate it properly.
160
00:19:04,920 --> 00:19:07,720
Another female settles down to lay.
161
00:19:12,440 --> 00:19:15,320
And another egg joins his collection.
162
00:19:34,600 --> 00:19:38,520
His final clutch may be huge, up to 50 or so.
163
00:19:38,680 --> 00:19:43,240
They've come from many different females
and been laid over a period of eight days,
164
00:19:43,400 --> 00:19:45,120
but all hatch together.
165
00:19:45,280 --> 00:19:48,800
The young pipe to one another
while they're still inside their shells,
166
00:19:48,960 --> 00:19:53,680
stimulating the eggs that are a bit behind
to speed up their development.
167
00:20:13,560 --> 00:20:18,360
The advantage of hatching simultaneously
is that the young, soon after they emerge,
168
00:20:18,520 --> 00:20:22,080
can go off and feed together
under Father's watchful eye.
169
00:20:55,320 --> 00:20:59,800
The open grassland is full of dangers
and there are very few places to hide
170
00:20:59,960 --> 00:21:02,560
from the many enemies
that lie in wait for the chicks.
171
00:21:02,720 --> 00:21:06,360
The maned wolf will certainly take one
if it gets the chance.
172
00:21:10,760 --> 00:21:15,400
It hunts alone, never forming packs,
seldom even seen with its mate.
173
00:21:15,560 --> 00:21:19,480
It maintains contact with others of its kind
by an occasional bark
174
00:21:19,640 --> 00:21:24,840
and by leaving its scent on bushes
and termite mounds, spraying its urine high up
175
00:21:25,000 --> 00:21:28,280
so that the wind will pick up the smell
and broadcast it.
176
00:21:30,200 --> 00:21:36,680
This wolf's tastes are, oddly, strongly
vegetarian. Fruit forms a large part of its diet.
177
00:22:00,280 --> 00:22:04,920
But it certainly takes birds if it can,
and the tinamou is particularly vulnerable,
178
00:22:05,080 --> 00:22:07,120
for it's almost flightless.
179
00:22:52,320 --> 00:22:57,200
Trees don't grow on the open plains of Argentina
and Brazil because, for much of the year,
180
00:22:57,360 --> 00:22:59,320
there is too little rain.
181
00:22:59,480 --> 00:23:03,960
During the dry season, the shallow lakes
are reduced to stretches of baked mud.
182
00:23:04,120 --> 00:23:10,520
Capybara, giant semi-aquatic guinea pigs,
crowd into the few shrinking pools that remain.
183
00:23:11,200 --> 00:23:14,800
Cayman are compelled to spend
much of their time out of water,
184
00:23:14,960 --> 00:23:19,800
and turtles jostle for places along the contracting
margins with the capybara.
185
00:23:21,960 --> 00:23:26,640
But during April, the clouds begin to gather
and in June they burst.
186
00:23:26,800 --> 00:23:29,880
(THUNDER AND RAIN)
187
00:23:38,080 --> 00:23:41,840
It's a testing time
for many of the grassland creatures.
188
00:23:53,120 --> 00:23:59,240
2,000 miles north of the Brazilian campo,
the grasslands of Venezuela, the Ilanos,
189
00:23:59,400 --> 00:24:04,360
flood over great areas, for the ground
is full of clay and holds the water.
190
00:24:05,400 --> 00:24:07,920
For some, this is exactly what they want.
191
00:24:14,520 --> 00:24:18,840
The Ilanos are flooded like this
for almost half the year.
192
00:24:19,000 --> 00:24:21,800
That's all right for those capybara.
193
00:24:21,960 --> 00:24:25,840
They are almost as much at home
in the water as they are on land.
194
00:24:26,000 --> 00:24:30,680
Some creatures, even such an unlikely-looking
swimmer as the giant anteater,
195
00:24:30,840 --> 00:24:33,360
manage to struggle to dry ground.
196
00:24:33,960 --> 00:24:36,920
The armadillo, too,
is very competent in the water.
197
00:24:41,720 --> 00:24:46,560
Many others, such as burrowing rodents that
might otherwise crop the grass of the plains,
198
00:24:46,720 --> 00:24:51,320
can't do so because they can't survive
being flooded like this every year.
199
00:24:51,480 --> 00:24:56,080
The grass, however, grows tall
and lives through even this hardship.
200
00:24:57,320 --> 00:25:02,960
2,000 miles farther north still, water lies
on the plains for many months on end,
201
00:25:03,120 --> 00:25:06,520
as snow on the prairies of North America.
202
00:25:07,440 --> 00:25:11,840
Here the temperature can drop
to 46 degrees below zero centigrade.
203
00:25:12,200 --> 00:25:16,520
The resistant grass survives it
but few animals can.
204
00:25:17,880 --> 00:25:23,200
The ground squirrels retreat to their burrows
and go into a state of suspended animation.
205
00:25:23,360 --> 00:25:28,000
Their temperature falls
and their breathing rate slows - they hibernate,
206
00:25:28,160 --> 00:25:32,800
using the absolute minimum of their body
reserves accumulated during the summer.
207
00:25:43,400 --> 00:25:47,320
A cousin of the ground squirrel,
another rodent called the prairie dog,
208
00:25:47,480 --> 00:25:52,280
does remain active, and during milder spells
it ventures out onto the snow
209
00:25:52,440 --> 00:25:54,440
to nibble what leaves it can find.
210
00:25:58,240 --> 00:26:03,760
The prairie chicken, actually a grouse, is one
of the few birds to stay on the winter prairies,
211
00:26:03,920 --> 00:26:09,640
for although there are no insects to be had now,
it can survive on nothing but seeds and leaves.
212
00:26:12,840 --> 00:26:15,920
Things are happening, however, below ground.
213
00:26:18,400 --> 00:26:21,480
The pocket gopher is still hard at work.
214
00:26:23,720 --> 00:26:27,320
Its winter food is roots,
and very nourishing they are,
215
00:26:27,480 --> 00:26:31,440
for many plants in autumn withdraw
much of their substance from withering leaves
216
00:26:31,600 --> 00:26:33,600
and store it in their roots.
217
00:26:38,720 --> 00:26:43,600
The bison manages to survive
even the coldest weather out on the prairie.
218
00:26:43,960 --> 00:26:46,680
Big animals are not as easily chilled
as small ones,
219
00:26:46,840 --> 00:26:49,760
and the bison is the most massive animal
in North America.
220
00:26:50,200 --> 00:26:52,320
A bull can weigh a ton.
221
00:26:57,680 --> 00:27:01,880
The extreme temperatures have,
in effect, put the grass into deep freeze,
222
00:27:02,040 --> 00:27:06,920
so that, although it's frozen solid,
such nutriment as it contained is preserved.
223
00:27:07,360 --> 00:27:11,160
The bison, being so big, have no difficulty
in sweeping away the snow
224
00:27:11,320 --> 00:27:13,680
and reaching the frozen tufts.
225
00:27:15,240 --> 00:27:19,360
Bison share the prairies
with pronghorn antelope which, in winter,
226
00:27:19,520 --> 00:27:22,360
often visit areas that the bison
have just cleared of snow.
227
00:27:22,760 --> 00:27:28,560
They are the swiftest animals in North America,
capable of speeds of 50 mph at full stretch.
228
00:27:30,840 --> 00:27:36,640
Coyotes, a small relation of the wolf, have little
chance of catching a young healthy pronghorn.
229
00:27:36,800 --> 00:27:40,440
But that doesn't mean they won't try,
and by chasing, they can discover
230
00:27:40,600 --> 00:27:45,800
if there are any antelope in the group that
are less than healthy and therefore catchable.
231
00:28:17,360 --> 00:28:19,840
Another joins the chase.
232
00:28:31,760 --> 00:28:35,600
The bitter cold and the shortage of food
kills many animals at this time.
233
00:28:36,240 --> 00:28:41,560
For the coyotes, a carcass is precious,
a mass of meat in an otherwise barren land.
234
00:28:41,720 --> 00:28:44,920
A pair has already taken possession
of this dead elk.
235
00:28:46,280 --> 00:28:49,240
A third arrives. There will be trouble.
236
00:28:54,120 --> 00:29:00,120
They signal their threats with bristling fur,
snarling lips but surprisingly little sound.
237
00:29:35,320 --> 00:29:39,800
As spring approaches, the temperature rises,
even below ground,
238
00:29:39,960 --> 00:29:42,840
and the winter sleepers begin to awake.
239
00:29:45,880 --> 00:29:51,360
Rattlesnakes, forced to take shelter from the cold,
frequently take over the deeper burrows
240
00:29:51,520 --> 00:29:54,720
made by prairie dogs
and there, ten feet below ground,
241
00:29:54,880 --> 00:29:58,320
sit out the winter
beyond the reach of the lethal frost.
242
00:29:59,000 --> 00:30:02,920
Sometimes as many as two or three hundred
will share the same hole.
243
00:30:03,440 --> 00:30:08,360
As the spring sun warms the air,
so they too slowly come to life.
244
00:30:13,480 --> 00:30:17,600
The prairie chickens leave the tall grass
country where they spent the winter
245
00:30:17,760 --> 00:30:22,480
and assemble on shorter turf,
for they are about to start their spring dances.
246
00:30:43,400 --> 00:30:47,640
Each male stays on a small patch of ground
that is his dancing stage,
247
00:30:47,800 --> 00:30:53,920
and there erects his feathery horns, inflates
his wattles and starts his stamping dance.
248
00:30:54,080 --> 00:30:58,960
(DRUMMING RHYTHM)
249
00:31:42,880 --> 00:31:46,680
The prairie dogs live
in such concentrations and such numbers
250
00:31:46,840 --> 00:31:50,200
that their patch of the prairie
is called a town.
251
00:31:50,360 --> 00:31:53,080
They mated below ground back in February.
252
00:31:53,240 --> 00:31:57,360
The youngsters were born a month later and now,
in the sunshine of early summer,
253
00:31:57,520 --> 00:31:59,560
they get their first view of the world.
254
00:32:23,440 --> 00:32:25,720
The bison, too, have their young.
255
00:32:25,880 --> 00:32:29,960
The thick woollen coat that protected them
through the winter is now far too hot,
256
00:32:30,120 --> 00:32:33,640
and the animals begin to shed it
in sheets and tatters.
257
00:32:41,560 --> 00:32:46,200
The bison, being such a big animal,
has a long gestation period, nine months.
258
00:32:46,360 --> 00:32:50,400
So, soon after the young are born,
courting starts again,
259
00:32:50,560 --> 00:32:53,600
and for the bulls
that involves battling with rivals.
260
00:32:53,920 --> 00:32:57,920
These jousts, which can be very punishing
and even end in death,
261
00:32:58,080 --> 00:33:00,800
establish a ranking among the bulls.
262
00:33:03,000 --> 00:33:07,840
The victors can then seek access to the cows,
which is another problem.
263
00:33:40,760 --> 00:33:46,000
The bison herds have a particular liking
for the grazing around the prairie dogs' towns,
264
00:33:46,160 --> 00:33:48,600
for the prairie dogs are good farmers.
265
00:33:48,760 --> 00:33:53,080
They deliberately cut down unpalatable plants
and remove dead material,
266
00:33:53,240 --> 00:33:57,080
and their constant cropping means
that the grass leaves around their burrows
267
00:33:57,240 --> 00:34:00,200
are all young and succulent,
and the bison like that
268
00:34:00,360 --> 00:34:03,760
just as much as the prairie dogs do.
269
00:34:16,120 --> 00:34:21,000
The rattlesnakes also haunt the town,
on the lookout for young prairie dogs.
270
00:34:21,160 --> 00:34:27,000
The shortness of the cropped turf makes it easy
for the town sentinels to see approaching danger.
271
00:34:38,360 --> 00:34:41,000
What to do about it is another question.
272
00:34:58,840 --> 00:35:01,920
Bolting down a burrow
is no defence against a rattlesnake.
273
00:35:02,080 --> 00:35:07,440
It will simply follow. The only thing to do is retreat
and whistle a warning to the neighbours.
274
00:35:07,600 --> 00:35:10,120
(HIGH-PITCHED CALL)
275
00:35:16,240 --> 00:35:19,840
Bison are cattle.
Like antelope and sheep, they are ruminants,
276
00:35:20,000 --> 00:35:25,360
dealing with the problem of digesting cellulose
by regurgitating pellets of grass they graze
277
00:35:25,520 --> 00:35:27,760
and giving it all a second chew.
278
00:35:27,920 --> 00:35:32,400
They also maintain a digestive broth
of bacteria in their huge stomachs.
279
00:35:33,040 --> 00:35:36,720
Only 150 years ago,
they lived in such numbers on the prairies
280
00:35:36,880 --> 00:35:39,840
that a herd could stretch
from one horizon to another.
281
00:35:40,000 --> 00:35:45,000
How many there were altogether is uncertain.
Thirty million is one of the lower estimates.
282
00:35:45,160 --> 00:35:49,040
That was a measure of the great fertility
of these natural grasslands.
283
00:35:49,440 --> 00:35:54,640
Today, most of the prairie has been turned over
to the raising of domesticated cattle for beef,
284
00:35:54,800 --> 00:35:58,520
or ploughed up to grow
domesticated grass, wheat.
285
00:35:58,840 --> 00:36:03,120
By the beginning of this century,
less than a thousand wild bison were left.
286
00:36:03,280 --> 00:36:09,400
But today, thanks to careful conservation,
there are some 35,000 living in reserves.
287
00:36:10,440 --> 00:36:15,840
The prairies receive comparatively little rain
because they lie in the centre of a huge continent
288
00:36:16,000 --> 00:36:19,120
and the Rocky Mountains screen off the rain.
289
00:36:23,120 --> 00:36:27,400
Across the northern Pacific,
the biggest continental mass of all, Eurasia,
290
00:36:27,560 --> 00:36:31,720
also contains a heartland
where relatively little rain falls -
291
00:36:31,880 --> 00:36:35,240
the grass-covered steppes
of Russia and Eastern Europe.
292
00:36:35,400 --> 00:36:40,040
And here another grass feeder survives
that once formed vast herds,
293
00:36:40,200 --> 00:36:43,320
an extraordinary antelope, the saiga.
294
00:36:46,920 --> 00:36:51,480
Its huge nose contains, internally,
a convoluted arrangement of passages
295
00:36:51,640 --> 00:36:55,320
lined with mucous glands
that apparently serve to warm and moisten
296
00:36:55,480 --> 00:36:58,600
the dry air of the steppes and filter out the dust.
297
00:37:08,200 --> 00:37:10,560
The steppes are not as fertile as the prairie
298
00:37:10,720 --> 00:37:13,920
and are ravaged
by regular and disastrous droughts.
299
00:37:14,080 --> 00:37:18,960
But the saiga seem to have adapted to this and
have a quite extraordinary rate of reproduction
300
00:37:19,120 --> 00:37:23,480
that enables them to recover their numbers
after such a catastrophe with great speed.
301
00:37:23,760 --> 00:37:28,360
The females, when they are a mere
four months old and only half-grown,
302
00:37:28,520 --> 00:37:31,040
mate and produce their first calf.
303
00:37:31,640 --> 00:37:36,000
After it is weaned, they grow rapidly, so that
by the beginning of the next breeding season,
304
00:37:36,160 --> 00:37:40,080
they are full-size, and then they quickly
breed again - and this time
305
00:37:40,240 --> 00:37:42,880
three quarters of them will produce twins.
306
00:37:44,080 --> 00:37:46,920
These animals, too,
were hunted close to extinction,
307
00:37:47,080 --> 00:37:50,480
but when people realised that
these natural inhabitants of the steppes
308
00:37:50,640 --> 00:37:54,600
could turn their grass into meat much more
efficiently than any domesticated animal,
309
00:37:54,760 --> 00:38:00,160
indiscriminate hunting was stopped and now
there are over two million in the Soviet Union.
310
00:38:02,400 --> 00:38:07,360
Travel south west from the steppes of central
Eurasia, the greatest of all temperate grasslands,
311
00:38:07,520 --> 00:38:11,520
across territory where there is so little rain
that not even grass can grow,
312
00:38:11,680 --> 00:38:16,120
and you come to the greatest
of all tropical grasslands - in Africa.
313
00:38:24,120 --> 00:38:27,280
Here there is enough rain
to create rivers and waterholes,
314
00:38:27,440 --> 00:38:32,920
so in the moist soils around them and on rocky
outcrops, a few trees manage to grow.
315
00:38:35,080 --> 00:38:39,960
In the more regularly watered parts,
thorn trees stand, distanced from one another,
316
00:38:40,120 --> 00:38:44,520
their widespread root-systems managing
to collect just enough water to sustain them.
317
00:38:44,960 --> 00:38:48,080
Elsewhere, there is only enough rainfall for grass.
318
00:38:49,560 --> 00:38:53,080
But young trees are threatened
not only by drought but by fire.
319
00:38:53,240 --> 00:38:56,920
It sweeps rapidly over the plains,
killing the tree seedlings
320
00:38:57,080 --> 00:39:01,480
but leaving the growing buds of the grasses,
close to the ground, quite unharmed,
321
00:39:01,560 --> 00:39:04,520
and green shoots of grass appear within days.
322
00:39:04,680 --> 00:39:08,240
So the fire, which starts so easily
in withered grass stems,
323
00:39:08,400 --> 00:39:12,280
is one of the factors that keeps
the country open, for grass.
324
00:39:15,360 --> 00:39:21,280
The grasslands of Africa stretch
in an immense and almost continuous arc
325
00:39:21,440 --> 00:39:25,920
from the Sahara in the north
down through East Africa
326
00:39:26,080 --> 00:39:30,520
and on to the great game plains
of Southern Africa and the Cape.
327
00:39:31,000 --> 00:39:36,880
During the eight million years or so of recent
history, they've varied quite a lot in their extent.
328
00:39:37,080 --> 00:39:41,000
At the moment, they are not as big
as they have been in the past.
329
00:39:41,160 --> 00:39:46,320
But during this period of time, the grasslands
have developed, and as they have done so,
330
00:39:46,480 --> 00:39:49,080
the animals that lived on them have evolved,
331
00:39:49,240 --> 00:39:52,360
the nature of one
reacting on the nature of the other.
332
00:39:52,520 --> 00:39:57,840
Today, there's a greater variety and a bigger
concentration of grass-living creatures
333
00:39:58,000 --> 00:40:01,880
on these African plains
than anywhere else in the world.
334
00:40:15,080 --> 00:40:19,320
Different lengths of neck, different
sets of teeth, different appetites,
335
00:40:19,480 --> 00:40:23,960
such variety means that almost
every growing leaf, short or long,
336
00:40:24,120 --> 00:40:28,320
of every kind of plains plant,
is eaten by something.
337
00:40:39,480 --> 00:40:43,440
This vast tonnage of meat
on the hoof has led, inevitably,
338
00:40:43,600 --> 00:40:46,920
to the appearance
of an abundance of meat-eaters.
339
00:40:48,800 --> 00:40:52,680
And they too are varied,
to exploit the variety of meat available.
340
00:40:55,040 --> 00:40:56,880
The serval seeks mice.
341
00:41:12,440 --> 00:41:16,920
The lions, hunting in teams,
butcher wildebeest and zebra.
342
00:41:20,720 --> 00:41:22,840
Hunting dogs do the same.
343
00:41:26,240 --> 00:41:30,240
The cheetah goes
for animals its own size, gazelle.
344
00:41:57,480 --> 00:42:01,480
Before grass spread over the plains,
the ancestors of grazing antelopes
345
00:42:01,640 --> 00:42:04,880
must have lived in bush country,
rather as dik-dik do today.
346
00:42:05,560 --> 00:42:08,560
The bushes don't produce many leaves,
but they are highly nutritious
347
00:42:08,720 --> 00:42:13,000
and there are enough in an acre or so
to sustain a pair of these tiny antelope.
348
00:42:13,160 --> 00:42:17,360
So the dik-dik mate for life
and are permanent residents of their territory.
349
00:42:17,520 --> 00:42:21,040
They know it intimately
and have their own trails and hiding places,
350
00:42:21,200 --> 00:42:24,200
and they mark out its frontiers
with special notices.
351
00:42:25,720 --> 00:42:29,880
The ritual is nearly always the same.
The female visits the midden first.
352
00:42:31,000 --> 00:42:35,960
The buck is stimulated to follow and habitually
goes through exactly the same sequence
353
00:42:36,120 --> 00:42:39,880
of smelling, urinating, scratching and dunging.
354
00:42:59,920 --> 00:43:05,080
When the ceremony is over, the buck marks
the nearby bushes with a sticky perfumed wax
355
00:43:05,240 --> 00:43:07,520
from a gland just below his eyes.
356
00:43:11,160 --> 00:43:16,960
Impala, however, live in more open country
and feed not only on bushes but on grass.
357
00:43:17,360 --> 00:43:21,160
Here they can't hide
and they find their safety in numbers.
358
00:43:21,320 --> 00:43:25,680
With so many sharp eyes and acute ears,
it's very difficult for a hunter
359
00:43:25,840 --> 00:43:27,720
to approach them undetected.
360
00:43:27,880 --> 00:43:31,480
But such a lifestyle obviously makes it
impossible for the animals to live
361
00:43:31,640 --> 00:43:35,040
in permanent pairs on their own territory
as the dik-dik do.
362
00:43:35,200 --> 00:43:38,680
Instead, the males and females
form separate herds.
363
00:43:39,200 --> 00:43:41,680
The bucks then battle among themselves.
364
00:43:42,000 --> 00:43:46,880
Those that win will leave the bachelor herds
and set up individual territories.
365
00:43:57,200 --> 00:44:02,120
When the victors have established themselves,
the does visit them, one after the other.
366
00:44:02,280 --> 00:44:08,120
It is a very exhausting business for the bucks,
repeatedly mating and fighting off challengers.
367
00:44:29,520 --> 00:44:33,960
After about three months of this,
the once dominant bucks are worn out.
368
00:44:34,120 --> 00:44:39,200
They yield to other, fresher males
and return to the bachelor herd to recover.
369
00:44:44,080 --> 00:44:46,840
Wildebeest live on grass alone.
370
00:44:47,240 --> 00:44:50,440
But the patchy distribution of rain
over the African plains
371
00:44:50,600 --> 00:44:53,920
means that they can't stay
permanently in the same place.
372
00:44:54,360 --> 00:44:59,080
They quickly exhaust pasture on one patch
of the plains and must move to an area
373
00:44:59,240 --> 00:45:03,160
where rain has recently fallen
and the grass is springing again.
374
00:45:03,320 --> 00:45:07,840
So the wildebeest are constantly on the move
and their social arrangements
375
00:45:08,000 --> 00:45:10,800
have to be different
from the dik-dik and impala.
376
00:45:11,480 --> 00:45:17,360
During the short breeding season, the males set
up small territories along the migration routes.
377
00:45:17,880 --> 00:45:21,720
They advertise their pretensions
by prancing around and snorting,
378
00:45:21,880 --> 00:45:28,680
seeking showy contests with rivals
to demonstrate their virility to passing females.
379
00:45:37,920 --> 00:45:41,000
The problem then is to keep
the females in their territory
380
00:45:41,160 --> 00:45:44,800
and prevent them
from moving on to a rival's patch.
381
00:46:01,480 --> 00:46:04,800
The young calves,
born only a few months before,
382
00:46:04,960 --> 00:46:11,480
adopt very early the jaunty, slightly crazy way
of carrying on affected by their fathers.
383
00:46:30,800 --> 00:46:35,160
Within two weeks,
the majority of the females are mated.
384
00:46:40,400 --> 00:46:47,240
And then, suddenly, almost overnight, the whole
herd, hundreds of thousands strong, vanishes.
385
00:46:47,720 --> 00:46:50,480
They've gone in search of fresh pastures.
386
00:46:52,200 --> 00:46:57,600
The varying growth of the grass over the year
affects the lives of people as well as animals.
387
00:46:58,160 --> 00:47:00,880
In the eastern part of the grasslands,
in the Sudan,
388
00:47:01,040 --> 00:47:04,160
the people keep herds
of semi-domesticated cattle.
389
00:47:04,520 --> 00:47:08,280
These are their pride and their wealth
and their livelihood.
390
00:47:10,760 --> 00:47:17,000
At night they pen them in enclosures made
from uprooted thorn bush, to keep out lion.
391
00:47:21,080 --> 00:47:26,320
The people can't settle in permanent villages,
for their cattle exhaust the meagre pasture,
392
00:47:26,480 --> 00:47:31,000
just as wildebeest do,
so periodically they too have to move.
393
00:47:31,240 --> 00:47:35,120
It is a nice question as to whether the animals
are being driven by the people
394
00:47:35,280 --> 00:47:39,760
or whether the people are, willy-nilly,
following the herds.
395
00:47:43,320 --> 00:47:49,560
Many people in the Sudan regard not only their
semi-wild cattle as their own personal property,
396
00:47:49,720 --> 00:47:54,600
but also the fully wild game
that regularly passes through their territory.
397
00:47:55,840 --> 00:48:00,720
The white-eared kob, the males black
and white, the females a delicate tan,
398
00:48:00,880 --> 00:48:03,200
live in the southern Sudan.
399
00:48:03,360 --> 00:48:07,000
Here, during the rainy season,
the does give birth to their young.
400
00:48:08,680 --> 00:48:13,600
As the rains end and the plains begin to dry out,
the herds begin to move north,
401
00:48:13,760 --> 00:48:18,040
following the new flush of grass
that springs from the receding waters.
402
00:48:20,600 --> 00:48:23,080
As they go, the herds are funnelled together
403
00:48:23,240 --> 00:48:28,720
by two rivers that flow closer and closer
to one another until eventually they join
404
00:48:28,880 --> 00:48:32,880
and the kob have no alternative
but to attempt to cross -
405
00:48:33,040 --> 00:48:35,840
and here the Merle people await them.
406
00:48:36,000 --> 00:48:38,400
(CHATTING)
407
00:48:40,560 --> 00:48:44,760
For the Merle, this is an annual bonanza
and a great celebration.
408
00:48:44,920 --> 00:48:48,600
Families have travelled from all over
the tribal territory to take part
409
00:48:48,760 --> 00:48:51,200
and to claim their share in their harvest of meat.
410
00:48:51,360 --> 00:48:56,040
If all goes well, there will be great feasting.
But that's by no means a certainty.
411
00:48:56,200 --> 00:48:59,800
If the herds don't appear,
there will be real hunger in the tribe.
412
00:49:08,520 --> 00:49:12,840
In the early morning, the hunters
cross the river to set up their ambush.
413
00:49:13,000 --> 00:49:15,480
There's no guarantee
that the kob will come this way.
414
00:49:15,640 --> 00:49:20,360
If the rivers are low, they may well try to cross
on a much broader front upstream.
415
00:49:32,320 --> 00:49:36,440
(MEN CALL OUT EXCITEDLY)
416
00:49:51,640 --> 00:49:56,360
For the kob now, there is no going back.
They have to cross.
417
00:50:23,680 --> 00:50:28,720
Day after day, the kob that have arrived
at this crossing attempt to run the gauntlet.
418
00:51:13,240 --> 00:51:17,160
It takes several weeks for the whole
migration to pass through.
419
00:51:18,200 --> 00:51:23,040
A million kob will make the journey.
5,000 of them will be killed.
420
00:51:23,560 --> 00:51:25,800
The Merle not only feast well now,
421
00:51:25,960 --> 00:51:30,920
they sun-dry the meat so that the families will
have full stomachs for many months to come.
422
00:51:41,440 --> 00:51:47,760
In spite of the Merle's ambush, the vast majority
of the kob reach the northern grasslands.
423
00:51:48,600 --> 00:51:53,640
There they will find enough food to sustain them
throughout the critical months of the dry season.
424
00:51:53,800 --> 00:51:59,200
And there, too, they mate, so that next year
herds will reappear to make the river crossing
425
00:51:59,360 --> 00:52:02,440
and provide the Merle, once more, with meat.
426
00:52:04,000 --> 00:52:06,560
And the grass, too, will spring again,
427
00:52:06,720 --> 00:52:12,600
this remarkable plant that can survive
intense grazing and burning and flooding.
428
00:52:12,760 --> 00:52:15,880
The one thing it can't tolerate is drought.
429
00:52:16,040 --> 00:52:21,720
If there is just a little less rain,
then its leaves wither, its roots shrivel
430
00:52:21,880 --> 00:52:25,760
and can no longer hold the soil together,
so that the wind can catch it
431
00:52:25,920 --> 00:52:28,720
and blow away the small nutritious particles.
432
00:52:28,880 --> 00:52:33,880
And then it's reduced to little more than sand
and the land becomes a desert.
433
00:52:34,320 --> 00:52:38,120
And it's to deserts that we're going
in the next programme.
434
00:52:38,170 --> 00:52:42,720
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