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Few birds have caught the human imagination
as powerfully as the eagle.
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Throughout the centuries,
this majestic bird of prey
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has been the symbol of strength and courage,
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such is the perfection of its design.
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There are 60 different kinds of eagles
throughout the world
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and all have this basic body plan.
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But eagles hunt many different kinds of prey,
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and to succeed they've had to adapt
the classic eagle blueprint,
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and these modifications have been spectacular.
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This is the signature
of the world's most successful eagle.
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In terms of design, the golden eagle
is a classic model.
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With just a few modifications,
it has colonised much of the world.
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The trademark of all eagles
is a hooked, rapier-like bill,
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but they use other tools for killing.
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The back talon pierces like a bayonet.
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The rest act like grappling irons,
crushing prey with an incredible force.
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Its surveillance gear is equally powerful,
magnifying two and a half times
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and resolving eight times more detail
than the human eye.
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It can see prey a mile and a half away.
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Flight reveals another defining feature -
broad wings that float on air.
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In the slightest updraft, five kilos of bird
becomes as light as a feather.
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Through evolution,
prey has become the natural designer,
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refining each eagle's body plan and behaviour.
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In Alaska, a cauldron of early morning mist
shrouds another classic model,
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one specifically for fishing.
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(HIGH-PITCHED SQUAWKING)
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The icy advance of the Arctic winter
has driven golden eagles further south.
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But for the bald eagle, the Chilkat River
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provides a welcome staging post
on their migration.
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(SQUAWKING)
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The black and white livery
is the trademark of many fish eagles.
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The steamy backdrop has formed,
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as thermal springs percolate the river
like a natural jacuzzi.
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Up to 3,000 bald eagles gather here,
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enticed by the fishy banquet
hidden beneath the icy surface.
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Volcanic heat acts as an ice-breaker,
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allowing salmon to spawn
during the cold heart of winter.
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These are chum salmon.
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Having spawned their next generation,
they're waiting to die.
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Like vultures, the bald eagles
simply have to bide their time.
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The pickings are easy,
but the competition is fierce.
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(SQUAWKS)
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He proclaims possession,
but still needs to feed quickly.
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(SQUAWKS)
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Fights are highly ritualised.
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(SQUAWKS)
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Pride, the only injury.
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A high concentration of food
allows many eagles to co-exist.
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A fine balance between tolerance
and aggression results in ritualised combat.
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(SQUAWKING)
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They might slip and slide, but grip pads
on their talons will clamp the slipperiest fish.
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Their two-toned uniform means birds with food
become flying advertisements,
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easily seen by other birds.
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(SQUAWKS)
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But bald-eagle etiquette allows
the bird in possession a moment to feed
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before the raider attacks.
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It might look like a bun fight,
but among the scrum the birds are taking turns.
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Ultimately, they all have a seat at the table.
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All fish eagles share similar characteristics
and most are gregarious.
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In contrast, other eagles tend to be solitary.
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Among them are the powerful
forest eagles of the tropics.
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A long tail and short wings
is their unique brand mark.
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The crowned is Africa's most ferocious eagle.
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(BIRDSONG)
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Its crested headgear only adds
to its imposing appearance.
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It hardly needs such embellishment.
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The nature of its prey says everything
about its power.
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In response, the eagle has developed
awesome weapons.
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The crowned is marvellously adapted
for forest hunting.
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The long tail gives manoeuvrability,
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while short wings squeeze it
through the smallest gap.
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Forest eagles have a body plan
shaped for hunting in woodland.
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Golden eagles could not survive here,
although, by changing their behaviour,
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they have invaded
some surprisingly wooded places.
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In the Dadia mountains in Greece,
golden eagles hunt over open forest,
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but their long wings create problems
when chasing their prey among the trees.
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They have found an unlikely alternative prey.
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Soaring as a search technique
is equally effective
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for finding tortoises.
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But stooping seems like overkill
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and to avoid crashing into trees,
it applies the brakes as it nears the ground.
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The armoured shell presents
an intriguing challenge.
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It simply doesn't have the right tools for the job.
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Its solution is ingenious.
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It flies to a favoured site,
where a rocky outcrop acts like a natural anvil.
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It then gains height.
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It then safely parachutes into the clearing.
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The impact separates the tortoise shell
into two halves - like loosening a lid.
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Eagles here feed almost exclusively
on tortoises.
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They've all learned the same trick.
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(SQUEAKS)
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In forests, tree nests are common,
but too many trees and the eagles can't hunt,
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even for tortoises.
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Dense forest has acted as a barrier,
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preventing the golden eagle reaching
South American and South-East Asia.
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But it nests throughout Europe,
North America and Asia,
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making it the most widespread
and successful of eagles.
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Strangely, the golden doesn't nest in Africa.
The reason why involves other eagles.
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These are steppe and lesser-spotted eagles
riding a thermal on their way to Africa.
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Using broad wings for lift, they glide
from this invisible elevator in search of another.
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They're now over Israel.
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By gliding from thermal to thermal,
they will save energy on the long journey ahead.
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Using this energy-saving flight,
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they may travel as much as 4,000 miles
without stopping for refuelling.
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They undertake this marathon flight
because in their home on the steppes of Asia
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their mammal prey hibernates over winter.
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Steppe eagles are smaller relatives
of the golden eagle, but only they migrate.
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By the time one reaches Africa,
it's lost a third of its body weight.
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In their northern homes, they feed
on small mammals, but here their tastes change.
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There are 16 other eagle species in Africa,
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so to avoid competition, the steppe
needs to find a gap in the food market.
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Besides scavenging, it eats mainly termites.
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Its African cousin, the tawny,
prefers small mammals,
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so the two avoid conflict
by pursuing different prey.
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Another way of winning the endless
competition for food is to be the biggest.
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The martial weighs in at six kilos,
with a wingspan of over two metres.
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This huge and ferocious bird
can show surprising tenderness.
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Just a single chick is reared every two years -
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family planning that matches
the number of birds to the available space.
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Amazingly, each pair of martials
needs 100 square miles to itself.
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Big birds not only need a lot of space,
they also hunt big prey.
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Even small antelope like this duiker are tackled.
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The hunter exploits cover as far as possible.
Surprise is everything.
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Even an eagle as powerful as a martial
only succeeds one time in five.
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The bateleur has a bizarre and unique shape
that helps it find a meal.
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It intersperses its ungainly flaps
with short glides, trying to gain height.
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Its tail is too short
to serve as an effective stabiliser.
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But soaring reveals the effectiveness
of its body plan.
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Its comparative instability
responds instantly to the tiniest updrafts.
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The short tail makes tiny, quick adjustments,
allowing it to soar at low altitude
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as it looks for carrion.
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With scarcely a wingbeat,
it can search 200 miles in a day.
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As it lands, its aerial grace vanishes again.
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Its flight technique allows it
to survey huge areas
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and spot carcasses that other eagles miss.
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With such a diversity of eagles in Africa,
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it seems surprising
that the golden isn't among them,
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but perhaps it is.
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Soaring above the rock kopjes
of the Matopos in Zimbabwe
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is the answer to the mystery of the missing eagle.
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These are black eagles.
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Except for the colour of their plumage,
they're almost identical in form to the golden.
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To survive here, the archetypal generalist -
the golden eagle -
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has had to become a specialist.
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(SQUEAKS)
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Remarkably, it now hunts just a single prey -
a distant relative of the elephant.
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Rock hyrax may look like rodents,
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but their hooves hint at this closer
and more surprising relationship.
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The landscape of broken rocks
offers their prey a maze of escape routes.
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To increase the element of surprise,
eagles often collaborate in pairs.
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They add to their prey's confusion
by hunting with the sun behind them.
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But the hyrax has evolved a countermeasure -
an iris in its eye that cuts down the glare.
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Being detected might seem
to be the ruin of a hunt,
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but this eagle is a decoy,
attracting attention away from its teammate.
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For black eagles,
competition starts with hatching.
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This chick is unlucky.
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It's three days younger,
and here sibling rivalry can lead to murder.
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The parents are attentive,
bringing back garlands of aromatic leaves
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to use as fly repellents.
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The black eagle uses this natural insecticide
to fumigate the nest, as many eagles do.
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But her devotion will not help the new hatchling.
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The older chick has summarily
dealt with the competition.
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This may seem harsh, but it has good reason.
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In the tropics, there are few vacant territories.
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Even one extra eagle may have trouble
finding a space.
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In temperate zones,
populations turn over quickly.
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So there eagles spread the risk by rearing more.
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But here, one offspring
is the more prudent investment.
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Laying two eggs is an insurance policy
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just in case one, for some reason, is lost.
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With so much competition in Africa,
any new environment is soon fully colonised.
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These are the skeletons of trees
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drowned when Zimbabwe's Kariba Dam
was created in the 1950s.
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They now provide perches and nest sites
for the African fish eagle.
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This species shares many characteristics
with the American bald eagle.
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They both have a bill perfect for filleting
and talons that act as fish spears.
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They also have grip pads on their talons
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and long, slender legs
that snatch their prey from the water.
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Because of internal reflections,
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the fish can only see out of the water
through a narrow window directly above.
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The fish eagle exploits the fish's blind spot
when hunting.
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It swoops in low and takes the fish by surprise.
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(SQUAWKS)
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Despite the occasional slip-up,
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they're so efficient that they can sometimes
spend as little as eight minutes a day hunting.
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There is only one type of fish eagle in Africa,
so it has no direct rivals.
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It's found wherever there is water.
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But not all water contains fish.
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This is Bogoria, a soda lake in Kenya.
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No fish live in this caustic waterˇˇ
but eagles still hunt here.
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Their prey are flamingos.
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The fish eagle is spoilt for choice.
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Up to two million flamingos
may congregate here.
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(CACOPHONY OF FLAMINGOS SQUAWKING)
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Several pairs of eagles live on the lake,
but they never seem to breed here.
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00:27:59,240 --> 00:28:02,760
Perhaps the flamingos are too heavy
to carry to the nest.
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00:28:14,880 --> 00:28:17,920
As the flamingos filter algae
from the caustic water,
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they always keep a watchful eye on the sky.
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00:28:53,560 --> 00:28:57,280
The eagle seeks out weak or isolated birds.
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00:29:04,120 --> 00:29:08,480
Its technique is to prevent the prey
getting fully airborne.
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00:29:34,360 --> 00:29:37,320
Dive-bombing weakens the bird.
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00:29:46,720 --> 00:29:52,000
The fish eagle may have adapted to new food,
but so have other eagles.
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00:30:00,160 --> 00:30:03,600
The scavenging steppe eagles
that first took us to Africa
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have here become pirates.
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For the fish eagle, it's easier to hunt again.
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It leaves the fighting to others.
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00:30:32,400 --> 00:30:35,800
(SQUAWKS)
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It's not only eagles that are its competitors.
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Black kites mob fish eagles relentlessly.
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Talons can be formidable defensive weapons,
but contact is rare.
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00:31:18,360 --> 00:31:23,480
Such aerial manoeuvring has developed
into highly ritualised displaysˇˇ
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ˇˇ among some fish eagles.
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00:31:31,200 --> 00:31:35,160
The white-bellied fish eagle
lives along the coasts of South-East Asia.
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00:31:38,560 --> 00:31:44,040
But here, near Penang, competition comes
from a surprising and dramatic source.
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This aerial battle is for territory.
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An eagle may rest from the fray,
but by simply watching the dog fight,
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it risks losing airspace.
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00:32:20,880 --> 00:32:26,400
These fights demand precision-flying
and often climax with the presenting of talons.
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As the eagles push their stunt-flying
to the limit, they make contact.
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Talons lockˇˇ and the eagles spiral.
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These spectacular contests are highly ritualised.
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And Talon-grappling is one of the most astonishing
displays of aerobatics in the natural world.
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Cartwheeling is a game of dare
that can end in death.
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The ultimate test of nerve.
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Other eagles cartwheel,
but fish eagles are the stars.
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00:33:34,400 --> 00:33:38,240
Forced to fight over the same food,
they have become skilled in the art.
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This is not an eel.
It's one of the most venomous snakes on earth.
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It needs to be handled with care.
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Sea snakes congregate here to breed.
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The eagle has refined its hunting skills
to such a degree
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00:34:14,320 --> 00:34:17,280
that it can grapple
with this potentially lethal prey.
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00:34:24,960 --> 00:34:30,920
The eagle has no immunity to the venom,
so it's forced into a deadly juggling act.
233
00:34:37,600 --> 00:34:41,560
Power-diving ensures
that the snakes are taken by surprise.
234
00:34:58,000 --> 00:35:02,560
Fishing over the open sea
has led to its wings becoming long and narrow,
235
00:35:02,800 --> 00:35:05,480
a shape more common among sea birds.
236
00:35:14,760 --> 00:35:19,440
This fish eagle has been able to adapt
its fishing technique to a different prey,
237
00:35:19,560 --> 00:35:24,360
but the forest contains eagles
that make hunting snakes a speciality.
238
00:35:39,280 --> 00:35:44,720
The crested serpent eagle
belongs to a group known as the snake eagles.
239
00:35:48,880 --> 00:35:53,800
Such a specialist prey
needs a radical re-shape of the eagle.
240
00:35:55,600 --> 00:36:00,880
It's adapted for walking and climbing,
allowing it to search in dense woodland.
241
00:36:12,840 --> 00:36:17,520
To tackle potentially venomous prey,
it pays to take it by surprise.
242
00:36:20,000 --> 00:36:26,240
Its small size and relatively short wings
allow it to fly amongst dense foliage.
243
00:36:40,080 --> 00:36:42,920
This serpent eagle has adapted to forest life.
244
00:36:42,920 --> 00:36:45,760
It's a home that it shares
with another group of eagles.
245
00:36:54,600 --> 00:36:58,640
Short wings for saving space
and a long tail for manoeuvrability
246
00:36:58,880 --> 00:37:02,160
is the recurrent solution for a life in the forest.
247
00:37:04,560 --> 00:37:08,000
It's a blueprint that has been perfected
by the hawk eagles.
248
00:37:13,160 --> 00:37:15,520
This is Blyth's hawk eagle.
249
00:37:16,240 --> 00:37:21,320
Its conspicuous crest is found in most
forest birds and is probably a signalling device.
250
00:37:22,240 --> 00:37:26,000
Long claws on the talons
are for plucking birds from the air,
251
00:37:26,080 --> 00:37:29,080
for this eagle is a fast and dynamic hunter.
252
00:37:31,960 --> 00:37:33,880
It's also tiny.
253
00:37:33,880 --> 00:37:35,800
It's among the smallest eagles,
being no bigger than a pigeon.
254
00:37:38,560 --> 00:37:41,520
Being small has advantages in the forest.
255
00:37:41,600 --> 00:37:46,640
In other environments, eagles have found
advantages at the opposite end of the scale.
256
00:37:48,520 --> 00:37:55,440
Japanese fishing boats off Hokkaido are
a magnet to the world's biggest fish eagle.
257
00:38:00,560 --> 00:38:05,560
With a two-and-a-half-metre wingspan
and weighing in at an incredible nine kilos,
258
00:38:05,840 --> 00:38:11,000
these Stellers are the sumo wrestlers
of the eagle world.
259
00:38:16,040 --> 00:38:19,400
Closely related to the bald eagle
but twice the size,
260
00:38:19,760 --> 00:38:23,480
they have a bill larger than any other bird of prey.
261
00:38:28,080 --> 00:38:32,840
The fishing fleet provides easy pickings -
the fish that fall from the nets.
262
00:38:36,840 --> 00:38:42,280
Even large fish are just a sushi snack
for these huge eagles.
263
00:38:53,920 --> 00:38:56,880
Stellers are among our rarest eagles,
264
00:38:57,040 --> 00:39:03,160
but as much as a third of the world's population
may gather here, drawn by free seafood.
265
00:39:18,680 --> 00:39:20,960
Remarkably, in strong winds,
266
00:39:21,160 --> 00:39:23,640
even the heavyweights
sometimes have problems losing height.
267
00:39:24,520 --> 00:39:27,880
They may have to spill the air
from their wings by whiffling.
268
00:39:48,520 --> 00:39:51,080
As they squabble over these free handouts,
269
00:39:51,280 --> 00:39:55,240
the heaviest and largest of the fish eagles
profits from human activity.
270
00:40:03,840 --> 00:40:09,520
In the Philippines, the greatest
of the forest eagles is not faring so well.
271
00:40:14,000 --> 00:40:19,920
This is the mighty Philippine eagle,
surely the most impressive of all the family.
272
00:40:25,080 --> 00:40:29,840
Its headdress is a flamboyant crown
that outclasses any other eagle.
273
00:40:30,120 --> 00:40:34,080
At over a metre in height,
this is the world's tallest eagle.
274
00:40:35,560 --> 00:40:39,520
Its splendid crown only enhances
its record-breaking size.
275
00:40:42,240 --> 00:40:47,160
Like the crowned eagle of Africa,
its talons are for monkey-sized prey.
276
00:40:58,600 --> 00:41:01,400
In the air, it is no less impressive.
277
00:41:01,600 --> 00:41:04,600
Its wings are very broad and have
a surface area larger than any other eagle.
278
00:41:18,280 --> 00:41:23,400
This shape is suited to slow flight
and manoeuvrability in the forest.
279
00:41:32,440 --> 00:41:35,640
But this eagle holds a less enviable record,
280
00:41:36,120 --> 00:41:38,240
that of rarity.
281
00:41:38,600 --> 00:41:41,080
This is the first film taken at the nest
in the last 20 years.
282
00:41:59,320 --> 00:42:02,440
Philippine eagles rear just one chick.
283
00:42:02,680 --> 00:42:04,880
This one is three months old.
284
00:42:05,200 --> 00:42:10,720
It will be another six months before it's fledged.
The parents will not breed for another two years.
285
00:42:14,720 --> 00:42:19,240
Such a low turnover suited a world
before human intervention.
286
00:42:19,680 --> 00:42:23,640
The eagle is now unable to reproduce
quickly enough.
287
00:42:26,000 --> 00:42:31,440
This remarkable view of the world's most
endangered eagle removing a monkey's tail
288
00:42:31,760 --> 00:42:34,480
is now, sadly, a rare sight.
289
00:42:43,400 --> 00:42:47,120
The Philippine eagle's forest home
is rapidly disappearing.
290
00:42:51,440 --> 00:42:53,400
(THUNDER)
291
00:43:07,600 --> 00:43:09,520
As the rainforest vanishes,
292
00:43:09,520 --> 00:43:11,440
so, too, do the eagles.
293
00:43:12,480 --> 00:43:15,440
Fewer than 200 may now remain in the wild.
294
00:43:19,360 --> 00:43:25,160
The fate of this magnificent forest eagle
now rests in human hands.
295
00:43:37,800 --> 00:43:43,520
Among the world's largest eagles,
the golden eagle group has its own star.
296
00:43:45,400 --> 00:43:50,680
The distinctive tail of this huge eagle
has given the species its name.
297
00:43:50,960 --> 00:43:54,320
The wedgetail is derived
from the golden eagle.
298
00:43:54,320 --> 00:43:57,680
When it arrived in Australia,
it found a continent empty of other eagles.
299
00:43:58,640 --> 00:44:01,760
Without competition, it evolved unchecked.
300
00:44:06,160 --> 00:44:10,800
Even young kangaroos aren't safe
from this fearsome hunter.
301
00:44:15,040 --> 00:44:20,560
It's found throughout the outback
and is Australia's only large bird of prey.
302
00:44:25,640 --> 00:44:29,360
Its population exploded
when forests were cleared for grazing
303
00:44:29,480 --> 00:44:32,480
and it thrived on the introduced rabbits.
304
00:44:38,360 --> 00:44:42,760
Now an introduced virus is wiping out
its new rabbit prey,
305
00:44:42,800 --> 00:44:45,520
so it's turning back to the old.
306
00:44:49,560 --> 00:44:52,280
Such young kangaroos present a challenge,
307
00:44:52,280 --> 00:44:57,000
but its lance-like talons have been known
to pierce a lung and even kill adults.
308
00:45:09,160 --> 00:45:12,120
In the hunt, the fan-like tail
gives quick manoeuvring.
309
00:45:27,960 --> 00:45:32,920
But even the fast turns that such a shape allows
can be outmanoeuvred.
310
00:45:38,400 --> 00:45:41,040
Hunting traditional prey is difficult,
311
00:45:41,160 --> 00:45:43,920
but today there are more modern ways
of getting meals.
312
00:45:59,240 --> 00:46:02,880
Roadside eating is the labour-saving alternative.
313
00:46:03,240 --> 00:46:07,720
There are no vultures in Australia,
and the wedgetail has taken on their role, too.
314
00:46:12,320 --> 00:46:18,840
The wedgetail is a golden eagle whose habits
have diversified in the absence of competition.
315
00:46:27,040 --> 00:46:31,520
But even the archetypal golden eagle
can show similar versatility.
316
00:46:34,560 --> 00:46:39,800
This is Kamchatka,
a remote wasteland in Eastern Siberia.
317
00:46:40,240 --> 00:46:45,800
Golden eagles are only able to survive here
because of the presence of Steller's eagles.
318
00:46:45,880 --> 00:46:51,520
Here the Stellers fish for spawning salmon
as the bald eagles did in Alaska.
319
00:46:52,000 --> 00:46:56,640
Only Stellers have bills strong enough
to break through the sockeye's armoured skin.
320
00:47:00,640 --> 00:47:05,200
But the golden eagle shows the adaptability
of its superb body plan
321
00:47:05,320 --> 00:47:07,880
by becoming a scavenger.
322
00:47:13,880 --> 00:47:16,480
It needs to feed quickly,
but by taking its chances,
323
00:47:16,520 --> 00:47:19,160
it can survive in one of the most
inhospitable places on earth.
324
00:47:22,000 --> 00:47:24,560
No other eagle is so successful.
325
00:47:25,280 --> 00:47:28,560
It's a living testimony
to the perfection of a classic design.
326
00:47:38,320 --> 00:47:45,080
More than any other, this flying masterpiece
lays claim to a simple accolade
- the word "eagle".