4بخش

By June the days are at their longest

and all across the northern hemisphere the broad leaves are hard at work.

On the east coast of North America it seems like any other summers evening

but tonight is special.

After seventeen years underground

creatures are stirring.

The nymphs of the periodical cicada have been biding their time.

Now they march like zombies towards the nearest tree, and start to climb.

At first, there are merely thousands

but soon, more than a billion swarm all over the forest.

The biggest insect emergence on the planet is underway.

They invade the upper branches, where they climb out of their external skeletons

and assume their adult winged form.

At first theyre white and soft, but they have until dawn to complete their transformation.

After an absence of seventeen years, the forest is now overrun by cicadas.

The adults are clumsy and very edible.

For turtles and other inhabitants of the forest

this is a feast theyre lucky to see once in their lifetime

and they gorge themselves while they can.

Times have never been so good.

The cicadas have no defenses and virtually offer themselves to their attackers.

The stream of insects is so relentless

that soon all the predators are full to the point of bursting

and still the cicadas come.

With the predators overwhelmed the survivors can achieve their purpose.

After mating, the adults lay their eggs and then their job is done.

In just a few days they will all die and the forest will fall silent.

The cicadas here, will not be heard again for another seventeen years.

Having fed the predators, the cicadas leave one final gift for the forest itself.

The nutrients in a generation of cicadas are returned to the soil, all at once

and the trees enjoy a marked spurt in growth.

This may be the single largest dose of fertilizer in the natural world.

In the great broad leaf forests of Eastern Europe

the days are beginning to shorten, and a primeval sound heralds the onset of autumn.

Male red deer are starting their rut.

The air is heavy with the scent of females.

The rules are simple.

Winner takes all.

Across the northern hemisphere the deciduous forests are changing.

Leaves that have provided food and shelter since the spring, are now shed.

In the broad leaf forests of Russia winter is particularly severe

but there will always be some who benefit from hardship.

Black vultures scavenge from the carcass of a seeker deer