The next time a mere human invokes the phrase "parental sacrifice" about themselves, they should check out the emperor penguins of Antarctica for a bit of perspective. As this stunning documentary attests, the magnificent and mysterious birds devote three-quarters of every year to a life-threatening expedition whose sole purpose is procreation. "March of the Penguins" is itself a remarkable feat, the result of a yearlong shoot on what Ernest Shackleton called "the coldest, windiest, driest and darkest continent on the planet."

The birds leave the sea--their element--to embark on what is not so much a march as a Sisyphean ordeal. It begins with their single-file procession inland to a breeding ground as far as 75 miles away, a place where the ice is thick enough that there's no danger of their chicks drowning. If all goes well, season-long monogamous pairings each produce a single egg, and the ensuing months are devoted to protecting it from temperatures that average 58 below. After a precarious transfer, fathers incubate the eggs while the mothers travel back to the sea to fill their bellies for baby food. In one of many astounding sights in the docu, hundreds of penguin papas huddle together against 100 mph winter winds, going without food for more than two months while balancing eggs on top of their feet. It's probably safe to say that, while waiting for the mothers to waddle back, the starving birds don't get much of a kick out of the Southern Lights flashing around them. Pairs that have become parents then take turns making the treacherous trek to the sea--and food--until the chicks are old enough to take the plunge.

Luc Jacquet and his intrepid crew have captured striking super 16mm images of the penguins in the cruelly beautiful terrain and in the relative serenity of their underwater feeding missions. Morgan Freeman delivers Jordan Roberts' narration with wry affection. And just when the writing seems guilty of anthropomorphizing--the penguins' story is one of love, we're told--we witness a moment of pure, terrible emotion. Freeman intones, of a mother whose chick has succumbed to the cold, "The pain is unbearable," and then we watch her try to steal another mother's baby. For emperor penguins and comfortable moviegoers alike, the fuzzy, gosh-darn adorable chicks are the reward at the end of this extraordinary ordeal. And a viewer can only hope that those brief months the birds spend diving and swimming each year are fantastic. Narrated by Morgan Freeman. Directed by Luc Jacquet. Written by Jordan Roberts. Produced by Yves Darondeau, Christophe Lioud and Emmanuel Priou. A Warner Independent release. Documentary. Rated G. Running time: 80 min