National Geographic: The Body Changers Page #6

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As adults, they are flying machines

dedicated to sex.

If we couldn't witness a caterpillar

turn into a butterfly,

we'd never believe

they were the same animal.

It's as astounding as a Cuisin art

transforming into a 747.

Some animals undergo one

major transformation in their lives.

Others change fashions

every year with the seasons.

Dogs may wear heavy coats in winter.

But lengthening days will cause

the fine underhairs to drop out.

Soon, this dog will be cooler

in his new spring wardrobe.

Some animals change

not only their coat but their color.

The arctic fox wears white

for stealthy winter hunting.

By summer, the coat is less than

half as thick.

Arctic birds like the ptarmigan

also change color.

In summer, they're as mottled as

the terrain.

By winter, the ptarmigan is a bird

of a different color.

Other prey species

like the arctic hare

must track the seasons

with their wardrobe.

Understatement is de rigueur.

If some animals change

for the seasons on the outside,

others are transforming

on the inside.

All over North America,

redwing blackbirds prepare for spring

with remarkable changes.

Males arrive from winter havens

to squabble for territories.

No one gets a home

without singing for it.

But this male is out of practice.

He hasn't sung much at all

for half a year.

But he's been quietly transforming.

It's now opening day

of a new season of song.

The transformation was

all in his head, literally.

The blackbird is a brain changer.

Over the past months, one tiny area

in his brain devoted to song

has more than doubled in volume.

With his new swelled head,

this male now woos females with song.

When a female becomes all a-flutter,

the serenade has succeeded.

The happy new couple flies off

to the shrubbery.

It's time for a little

two-in-the-bush.

The burgeoning brain of the male may

have kept the sexes in tune this season.

Transformation promoted communication

which helped launch the next generation.

Late in the summer, blackbirds glean

the fields for the last easy morsels.

Males will transform once again.

The brain's song area dwindles,

along with sweet serenades for sex.

Birds are in good company when

it comes to changing for reproduction.

For most of its life,

a flowering plant makes stems and

leaves, a single pattern repeated.

But when the right conditions arrive,

of temperature, daylight, or rainfall,

a plant will suddenly transform,

producing a brilliant package of

sex and advertising.

As one poet put it,

"The flower is a leaf mad with love."

Deer browse among blossoms,

eating tender leaves and grasses.

A once flowering feast is

transformed into a pile of dung.

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