deep in an underground
cave an african savannah elephant is on
an unusual mission
in total darkness she's digging out
salty rocks from a 24 million year old
volcano
this is the only place on earth where
this exceptional behavior can be
observed
on the border between uganda and kenya
mount elgon
is an extinct volcano with a crater
that's 20 kilometers wide
it was once africa's highest mountain
far exceeding kilimanjaro
but millennia of erosion have reduced
its height to 4
321 meters
on its forested eastern flank several
groups of caves
lead deep into the volcano
elephants forage during the daylight
hours in the thick groves of bamboo
[Music]
as herbivores they receive most of their
nutrients
through digested vegetation or water if
these sources don't meet their dietary
requirements
they supplement them by eating soil or
rocks
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but the elephants here have taken this
phenomenon one step further
when the sun goes down the animals make
their way up the slopes of mount elgon
the track leads to a dark entrance
behind this waterfall lies ketum cave
a 150 meter long 60 meter wide
and up to 10 meter high deposit of
life-preserving salt
at the cave entrance large footprints
are evidence
of the elephant's visit
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deep scratches on the walls and roof are
the first signs they've been quarrying
the mineral-rich rock
but most of the activity takes place
even deeper underground
[Music]
at least a dozen elephants file into the
cave
it is so narrow in places they have to
squeeze their bodies along the passage
all the elephants are female some are
pregnant
while others have brought their
offspring with them female elephants
need large amounts of minerals during
pregnancy and lactation
and here they can find them in abundance
an elephant visit might last up to six
hours
but not all this time is spent mining
rock
finding their way through the cave takes
time too
[Music]
this young elephant navigates in total
darkness
using its trunk
it will take many visits for it to learn
the intricate structure of the cave
the elephants can't just lick the rock
their tongues aren't long enough
instead they scrape the salty earth from
the walls with their stuffy tusks
and collect the mineral rich sand in
their mouths
[Music]
the rocks are rich in calcium magnesium
and natrium
a study examining samples found they
contained more than 100 times the amount
of natrium per gram
than the average level found in plants
[Music]
[Applause]
these walls are examined for every last
grain of mineral
at a steady 13.5 degrees celsius
the air in the cave is pleasant night on
the mountain usually gets a lot colder
than the constant temperature in the
depths of the caves
[Music]
elephants have been visiting these caves
for centuries
possibly even millennia over time
they've modified and enlarged the caves
digging their way deeper and deeper into
the mountain
creating chambers that can be up to four
meters tall
[Music]
after hours of salt mining the elephants
stop work
and leave the cave
the route into the cave and the
technique of scraping the walls
are passed down from generation to
generation
a unique tradition that only exists here
on mount elgon
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