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Are you familiar with the word symbiosis?
It's a fancy term for a partnership between two different species,
such as bees and flowers.
In a symbiosis, both species depend on each other.
I want to tell you about a remarkable symbiosis
between a little bird, the Clark's Nutcracker,
and a big tree, the Whitebark Pine.
Whitebark grow in the mountains of Wyoming, Montana and other western states.
They have huge canopies and lots of needles,
which provide cover and shelter for other plants and animals,
and Whitebark feed the forest.
Their cones are packed with protein.
Squirrels gnaw the cones from the upper branches
so they fall to the ground,
and then race down to bury them in piles, or middens.
But they don't get to keep all of them;
grizzlies and black bears love finding middens.
But there's more to a symbiosis than one species feeding another.
In the case of the Clark's Nutcracker, this bird gives back.
While gathering its seeds, it also replants the trees.
Here's how it works: using her powerful beak,
the Nutcracker picks apart a cone in a treetop,
pulling out the seeds. She can store up to 80 of them in a pouch in her throat.
Then she flies through the forest, looking for a place to cache the seeds
an inch under the soil in piles of up to eight seeds.
Nutcrackers can gather up to 90,000 seeds in the autumn,
which they return for in the winter and spring.
And these birds are smart. They remember where all those seeds are.
They even use landmarks on the landscape --
trees, stumps, rocks --
to triangulate to caches buried deep under the snow.
What they don't go back and get, those seeds become Whitebark.
This symbiosis is so important to both species
that they've changed, or evolved, to suit each other.
Nutcrackers have developed long, tough beaks
for extracting seeds from cones,
and Whitebarks' branches all sweep upwards
with the cones at the very ends, so they can offer them to the Nutcrackers as they fly by.
Now, that's a symbiosis:
Two species cooperating to help each other for the benefit of all.


【TED-Ed】互利共生 - 不同物種間的驚奇合作! Symbiosis: A surprising tale of species cooperation - David Gonzales

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