(no audio) (no audio) (bright music) - [Narrator] It's strange that the journey of a monarch butterfly begins at the end.

At the bloom of spring, in the mountains of Central Mexico, a weathered monarch uses the end of its life to find milkweed, a flower whose leaves will nurture a new generation of monarchs, the initiation of a cycle.

The first generation emerges from a chrysalis with their inherited bright orange wings and sets off north.

At the end of their short lifespan, they birth the second generation of monarchs.

This generation is born to warmer weather and longer days.

They set off north again, following the sun, using instinct to continue toward the direction of their parents.

(bright music continues) They defy borders as they navigate through the odd familiarity of a new land.

(bright music continues) After traveling another great distance through a new terrain and sensing the end of their life's journey, they birth a third generation.

Like the generations before, they transform from egg to caterpillar, to chrysalis, to butterfly, flying north one last time, reaching the easternmost part of the United States.

There, they mate, they breed, they die.

The offspring day leave will carry out the end of a cycle.

(family members talking) This final generation is called the migration generation.

They'll use their long lifespan differently than the three generations before.

They take flight from their birthplace and head south, not stopping to mate or reproduce, they just fly.

For two months, they fly over 3,000 miles across mountains and valleys, through forests, over rivers, through the streets of cities and neighborhoods, reaching new destinations and milestones, carrying the stories and wishes of their predecessors on the black lines of their orange wings.

They rest throughout their long journey, conserving their energy so they can make it to the end, (gentle music) finally reaching the very place they descended from, the oyamel trees in Mexico, fulfilling a legacy that began with their ancestors, the ones who knew that their dream would be successfully carried out in some way.

It's strange that the beginning starts at the end.

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