This is a documentary feature about migratory birds. If you think that sounds dull, you'd be wrong. This is a surprisingly gripping story of survival, one of epic proportions.

The cinematography is breathtaking. At times we seem to be riding on the back of a bird or as part of a V formation of honking geese. You really get an intimate appreciation of the muscular power and the endurance of these creatures as they make their annual migrations from one end of the earth to the other.

We join a bald eagle as it soars over the Grand Canyon, follow Canada geese as they flap past the twin towers in Manhattan and the Statue of Liberty, and watch cranes dancing over Saharan sand-dunes. The journeys span thousands of miles taking in en route Monument Valley, the Eiffel Tower, The Great Wall of China, Himalayan storms, crashing icebergs and Amazonian torrants.

What makes this different from the conventional nature documentary is its minimalist narrative. Writer, director and narrator Jacques Perrin, who previously made the celebrated Microcosmos, only interjects occasionally with meditative thoughts on his subjects. "What if we understood that our borders did not exist, that the earth is a one and only space and what if we learned to be free as birds," he says and lets the footage do most of the talking.

He offers occasional comments on how the birds choose their flying routes and puts the flights to an eclectic, new agey soundtrack with good effect. A few lines of text introduce each new species of bird (many are covered) and tells us how many miles the birds migrate each year. Then you are left to watch and share the filmmakers' awe.

If the story is the journey, then the drama is in seeing how these birds survive the natural elements and human intervention. It's heartening to see a naval destroyer becoming a resting point for a fatigued bird that otherwise might not have made it across the ocean, depressing to see geese that have endured hundreds of miles of flight suddenly drop like stones out of the sky as they are picked off by hunters.

To its credit, the film doesn't get sentimental. While there is much that is wonderful, nature and man frequently prove malevolent forces. For example, a group of red-breasted geese migrating through Eastern Europe decide to put down in a smoke-bellowing factory. In their sartorial black, white and ruddy plummage, they look like a group of dinner party guests who are lost as they waddle through the industrial complex. It's almost amusing, until one of them sinks into a pool of oily sludge and wings greased, struggles helplessly to get free as the others fly off.

Elsewhere, a bird with a broken wing, vainly fends off an army of tiny crabs on an African shore. Nature is shown "red in tooth and claw". Spring brings fluffy youngsters, but also hungry predators.

Of course, to make such an interesting film about birds, the filmmakers had to go to great lengths to overcome our natural vertically challenged state. The shoot took 5 teams, 17 pilots and 14 cinematographers through forty countries and seven continents over the course of three years. Using gliders, helicopters, remote-controlled models, micro-light aircraft and balloons the filmmakers were able to get the stunning footage.

Some of the birds were "actors", which had been raised in captivity to allow the crews to get close to them. Perrin used techniques like exposing birds to the sounds of cameras before hatching and made sure that the new-born chick first saw a crew member so that it would be comfortable with filming.

In this respect it may not seem quite as "pure" as it first appears, but it would be difficult to get a more compelling bird's eye view of the world.