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Three out of every four Monarch butterflies that have ever lived have lived a month or less.
This isn't out of the ordinary - it's the typical lifespan of a Monarch.
But the remaining one butterfly is tasked with accomplishing the seemingly impossible,
extending its lifespan six, possibly even twelve times the length of the others.
If this select 25% of the Monarch population fails in its task, the species will face certain extinction.
How and why they must achieve this is due to an elaborate web of factors operating on
both a miniscule and grand scale.
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In summer months, Monarch butterflies make their home throughout the northeastern regions of North America.
These seasonal habitat areas are generally warm, and the Monarchs are able to feed on the nectar
of various flowering plants.
These months are also the breeding season for Monarchs, and the butterflies lay their eggs almost exclusively
on the leaves of the milkweed plant.
Monarch caterpillars depend on the milkweed as their sole food source during their two week period of growth.
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Each of these Monarch butterflies has an expected lifespan of two to six weeks,
a short but relatively easy life for the insects.
Three generations of Monarchs will live their lives in these summer breeding grounds before their
seasonal home begins to show signs of a dramatic shift.
The same habitat that in the summer often exceeds 90 degrees Farenheit can regularly
fall below freezing point in the winter.
The delicate bodies of the Monarchs, which each weigh less than a paperclip, are not able to withstand
these harsh conditions. IF they remained, they would undoubtedly freeze.
As such, the following generation of Monarchs must undergo a significant shift of their own, equipping their bodies for what is the most important and demanding six months of every annual cycle.
Every year, the fall and winter months decide the fate of the Monarch butterfly population.
The butterflies must seek a home elsewhere.
From generations of experience the butterflies know that such a place exists.
The only problem is that it lies nearly 2,000 miles to the south.
In order to complete such a journey, the Monarch must significantly extend its lifespan
by changing the very biological mechanisms of its body.
This generation of butterflies enters a state called diapause in which each butterfly halts all
reproductive function and devotes bodily resources strictly to survival.
The Monarchs take their cue to depart from the weather and possibly even the position of the sun. Their destination is a secluded mountain habitat in the fir forests of central Mexico.
This habitat remains warm even in the winter, and as such, is the only suitable haven for
the traveling butterflies.
The Monarchs' path south will take them two months to navigate, as they trace the eastern edge of
North America, before cutting westward and finding their place of safety.
They rely on the aid of natural forces to propel their movement. As warm air ascends, the resulting effect, called a thermal, can lift the butterflies, 05:14.000 --. 05:18.000 while air currents can accelerate them forward.
It's by no means an easy task, and some butterflies won't reach their destination.
But those that do are able to ensure the survival of their species.
By the springtime, their bodies are able to exit diapause and produce the first generation of
a new annual cycle. 05:40.000 Two thousand miles in just a few short months is a remarkable feat for an organism with
a wingspan of four inches or less.
Taking into account the radical changes that must occur for a single generation of butterflies to
make this journey, the migration is one of the most astounding biological realities in the natural world.
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