Fathers of the long winter night

Almost every animal that breeds in Antarctica does so in summer, when the sea ice breaks up, the sun barely sets and food is easy to find. The emperor penguin does the opposite. According to the Australian Antarctic Program, emperors are the only animals that breed during the Antarctic winter.

That choice shapes everything about their lives.

A colony on the ice

Emperor penguins do not nest on land like most penguins. Most of their colonies, the Australian Antarctic Program explains, are on fast ice — sea ice that is locked in place between islands or grounded icebergs. Colonies range from a few hundred to more than 20,000 pairs.

The breeding cycle begins in autumn, around April, when the sea ice forms again. Adults arrive well fed: they can weigh up to 40 kilograms at the start of the breeding season, and when they are fattening up they can eat as much as six kilograms of food a day. They will need every gram.

Nine weeks on an empty stomach

After the female lays her single egg, she passes it to the male and returns to the sea to feed. From then on, the egg rests on the male’s feet, tucked under a warm fold of skin.

The British Antarctic Survey states that the male incubates the egg for nine weeks without eating, relying on a thick reserve of fat to survive. He does this in the darkest, coldest part of the year, when emperor colonies can be hit by blizzards of up to 200 kilometres per hour.

The huddle

A single penguin standing alone in those conditions would lose heat quickly. So the males stand together.

On very cold days, the Australian Antarctic Program notes, as many as ten emperors can pack into every square metre of a huddle. The temperature inside can rise as high as +24 °C. Huddling cuts heat loss by as much as 50 percent — and that is what allows the males to survive the long incubation fast.

A huddle is not still, either. During a 48-hour blizzard, a whole huddle may drift as much as 200 metres.

Their feathers are part of the defence too. They are so dense and tightly packed that, according to the Australian Antarctic Program, it takes winds of more than about 110 kilometres per hour to ruffle them.

Hunters of the deep

When emperors are not standing on the ice, they are among the best divers of all birds. They mostly forage at depths of 150 to 250 metres, and a typical dive lasts three to six minutes. The deepest dive on record reached 565 metres, and the longest lasted 22 minutes.

These numbers are a reminder that the emperor’s life is lived in two very different worlds: the open water, where it hunts, and the frozen surface, where it breeds and raises its young.

A future tied to sea ice

Because the colonies stand on sea ice, the species depends on that ice forming at the right time and staying put long enough for the chicks to grow up. If the ice breaks up too early, the chicks may not yet be ready for the sea.

The emperor penguin is listed as endangered, and the Australian Antarctic Program reports that populations are projected to undergo a moderately rapid decline over the next three generations. For an animal so well adapted to the cold, the greatest risk is not the cold itself, but losing the ice it stands on.

Why it matters

The emperor penguin has evolved to do what no other animal does: raise its young through the Antarctic winter. Its survival strategy is cooperation in its plainest form — thousands of birds sharing their warmth on the ice. Its future depends on that ice.