Following Narwhals

Left: The treacherous journeys made by narwhals have been witnessed for the first time Photo: PAUL NICKLEN/BBC

Hard to find these creatures!:

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 groups 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.

...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.

..."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.