What is interesting is their ability to migrate through the ice in the face of the obvious and apparent dangers. They pull it off year after year.
The Arctic is a harsh environment but is a lot less fragile than some let on.
Until the globe warms up to the top end of the Holocene temperature range and stabilizes there with only modest variation, the arctic will hang on to its summer ice pack. This does not need to be and will change once we reforest the Sahara back to conditions prevalent during the Bronze Age.
Narwhals filmed for first time on migration
Narwhals, known as ice unicorns for their long tusks, have been filmed for the first time as they make their treacherous migrating along the cracks in the Arctic sea ice.
By Richard Gray, Science Correspondent
Last Updated: 9:13PM GMT 07 Feb 2009
The treacherous journeys made by narwhals have been witnessed for the first time Photo: PAUL NICKLEN/BBC
These unusual whales are rarely glimpsed in the fleeting moments they break through the ice that covers their underwater world.
But spectacular aerial footage captured by the BBC shows how the gruops of narwhal, with tusks up to eight feet long, crowd their way through narrow gaps between the ice sheets as they attempt a dangerous spring migration in the search for food.
It comes as new research is also revealing how these rare and strange-looking mammals are under threat from changing conditions in the Arctic.
Scientists studying the impact of climate change on the Arctic have concluded that narwhals are even more vulnerable than polar bears, which rely upon the ice to hunt. They claim that without the ice to shelter them, narwhals will become more vulnerable to predators and competition from other whales.
"Narwhal need predictable conditions so they can time their migration right and get to their food sources at the right time," added Dr Kristen Laidre, a polar biologist who is carrying out the research on narwhal at University of Washington. "They are really very specialised animals that have adapted to live amid the ice, so if the ecology of the Arctic changes then it can impact on the whole food chain.
"The areas they are found are extremely remote, so they are difficult to study. We still don't know how they manage to find open water within the ice. Each year the ice breaks up in different ways, but they time their migration at the right moment."
The narwhals, which feature in the first programme of the BBC's latest natural history series Nature's Great Events, were filmed during their annual migration north from the west coast of Greenland to their summer feeding grounds in the fjords and bays beyond Lancaster Sound.
They form the vanguard of animals to migrate north as rising spring temperatures and winds start to break up the vast stretches of sea ice that form in the Arctic Circle during the freezing winter months.
The film captures the thousands of narwhals as they make the annual trip along thin channels in the ice in the ice in groups of 20 or 30, all swimming in perfect unison as they surface for air.
Occasionally channels close up and the narwhals have to swim to find openings in the ice further along their route or they will drown. The animals can also become trapped if the ice sheets close up above them and the narwhals have to break through thin sections of the ice in order to breathe.
To get the footage film crews had to travel 30 miles out on the sea ice while it was starting to break up.
Justin Anderson, producer of the programme that follows the springtime melting of the Arctic ice sheets, said it took three weeks before they found the elusive whales.
He said: "The location is very remote and the ice was breaking up all the time around the film crew.
"When you see them, it is hard to believe they are real – they seem almost mystical as if they have come straight from some kind of fantasy world."
Narwhal tusks are thought to be the inspiration for the legend of unicorns and they can fetch thousands of pounds. Queen Elizabeth I is said to have paid a fortune for a narwhal tusk which she used as a sceptre.
Only male narwhals have tusks and they were originally thought to be used in "fencing" as males competed for mates. Recent research, however, has suggested the tusks could also act as some sort of super-sensory organ that allows them to detect changes in water temperature and salinity.
Nature's Great Events follows six periods of dramatic seasonal change in different parts of the world, including the salmon run in north America, flooding on the Kalahari and shoals of sardines up to 15 miles long migrating off the coast of South Africa.
In one heart-rending scene, a pride of hungry lions in Africa's Kalahari attack and kill a baby elephant in broad daylight. Such behaviour is considered to be extremely rare and it is the first time such an attack has been filmed.
Although lions are known to attack elephants, they usually do it under cover of darkness when the elephants are unable to see. It is thought that some prides are adapting to increasingly difficult conditions in their habitats to hunt bigger and more difficult prey.
Chris Carbone, a carnivore ecologist at the Zoological Society of London, said: "Lions do occasionally hunt really big prey that weigh up to one tonne, but that is pretty unsusual. They usually stick to zebra and wilderbeast that can weigh up to 200kg. With a social species like elephant, the adults will try to protect the young so it is a big risk. But lions are very adaptable and there are lions that specialise in hunting giraffe."
Nature's Great Events will begin on Wednesday 11 February on BBC One at 9pm.
Weight: up to 3,500lbs
Length: up to 15.5 feet
Ivory tusk: Actually a left front tooth that grows to 8ft
Dive more than 3,000 feet
Feed on arctic cod and squid
Related to other toothed whales such as orca and sperm whales