Every autumn one of the world's most spectacular animal migrations takes place in a little-visited corner of Georgia. Tag along with one band of shepherds as they make their deadly, boozy journey from the mountains of Tusheti to the plains of Kakheti.

Summers offer lush green grass for grazing, but autumn comes early to Georgia's Tusheti mountains. By early October, local shepherds are rounding up their flocks and moving out before winter takes hold.

A group of six young friends with their 1,200 sheep are among the dozens of shepherds and their flocks who spend their summers in the Tusheti mountains. It will take them three days to trek from their base village down to the safety of the plains.

The tacit leader of the group is Sulkhan Gigoidze. The 29-year-old dropped out of a technical institute to tend sheep. "I didn't want to be around people" he says.

With the formidable 2,800-meter-high Abano Pass looming ahead, the second day of the migration promises to be the most intense. The morning is spent winding along alpine lakes and watching out for the rocks that occasionally clatter down the cliffs.

For one member of the clan the migration will be a new experience. "Georgik," a 3-month-old Georgian shepherd, was rejected by his mother as a pup, and is treated as a favorite by the men.

The Georgian shepherd is a tough, ancient dog breed that helps keep the sheep in formation and protects them from wolves.

The dogs are bred to be the same color and size as the sheep they protect. It's impossible to spot the dogs from a distance, meaning the wolf packs that stalk the migrating sheep must treat all flocks with caution.

Dato Chkhareuli drives a group of sheep that got disoriented while climbing a serpentine road.

At the base of the pass the men pause for lunch -- a bag of salty sheep cheese, bread, a tin of stewed fish…

...and ''chacha,'' a viciously strong liquor made from the leftovers of wine production. The shepherds down three shots each. Every swill is accompanied by a toast -- to the mountains, guests, and to a friend who died recently on the road they're about to take.

Immediately after lunch the climb begins. The road over the Abano Pass is regarded as one of the most dangerous on Earth.

A truck passes carrying the wreckage of a vehicle that toppled off the road. According to group leader Gigoidze, the driver of the vehicle was the dead friend honored with the lunchtime toast.

Gigoidze watches for stragglers at the back of the flock. As the sheep climb, the rain turns to sleet, and then snow.

Around 85 percent of each flock is female. The Tusheti sheep are known for their resilience and rich, buttery meat. Their fleece is too coarse to be sold and is usually burned after shearing. The breed boasts a wobbly lump of fat above the hind legs that serves as a kind of emergency energy reserve. Each sheep is worth around $60.

A buffeting wind tugs at the flock as it crests the pass. With no shelter to be had, the sheep push ahead. The animals need to get to the relative warmth of the lower altitudes as quickly as possible.

On the other side of the pass the men turn off the serpentine road and direct the flock straight down the mountainside.

The sticks the men use for thwacking wayward sheep come in handy on the risky descent.

As the sheep pick their way down the mountain, the weary dogs snatch sleep where they can.

Little Georgik is exhausted, and yelps in fright at some of the steeper sections of the mountain. The men help carry him over the rougher sections of the path.

The flock rejoins the road, but only for a short time. It's a race against darkness to descend from the freezing heights of the mountains.

As the sheep cross below the timberline they plunge straight down slopes that look impossibly steep.

As daylight disappears the exhausted flock files down the last sections of the day's trek. After 12 hours of near-continuous marching, Sulkhan counts the losses -- eight sheep, a typical number for a large flock crossing the pass.

If the sheep stop to rest from injury or exhaustion they soon die of exposure, fall prey to wolves, or are taken straight to slaughter by passing locals.

After the shepherds make a kind of rudimentary camp they find the wood is too wet to burn. One of the men stuffs one, then a second, rubber boot into the smoldering logs and the fire is soon roaring.

The men get dry as best they can, with countless shots of chacha knocked back in the process, before they finally curl up for the night. Little Georgik slinks inside Chkhareuli's felt sleeping bag.

The following day the flock moves into civilization and the T-shirt weather of the plains.

The first priority for the men is a cold beer from one of the village stores.

With the mountains far behind, the flock will spend one week grazing on the plains to get used to the mild weather before continuing around 200 kilometers to winter pasture along the border with Azerbaijan.

With the toughest part of his journey behind him, Georgik has a spring in his step once more. Soon though, he will learn that what comes down must go back up. In spring the return journey into the mountains will pose an even tougher test. By that time he'll be a fully-grown dog too big for much sympathy from the men, and definitely too big to sneak into any sleeping bags.