冰雪世界 16

In some ways these birds are the penguins of the north.

They seek bare rock on which to lay their eggs

and they look rather like penguins too.

Unlike Antarctica,

the Arctic can be reached by land-based predators

which is why little auks have kept the ability to fly.

They use scree slopes to protect their eggs,

burrowing up to a metre beneath the rocks.

At the height of summer the sun never sets

but just skims the horizon before rising again.

Migrants return to the Arctic from far and wide.

They've come to make the most of the brief flush of food

and to produce their young.

Sandhill cranes have travelled all the way from New Mexico.