The Making of Stone Sheep
Spatsizi
by Monty Bassett

It was the sound of parting Velcro and the engine blast of a 747 taking off. Or, sheet lightening ripping across the face of violent storm. Or, the sound of my rip-stop nylon tent being torn apart inch by inch by hurricane-force winds.

In the dark I frantically searched for my knife. The tent stakes had come out on the windward side. If the tent blew towards the adjacent cliff, with me inside, I'd never find the door in the chaos. I prepared to cut my way out.

I yelled to Cas Sowa, the film's cameraman. His tent was closer to the cliff. No answer. The wind either deadened my voice, or maybe worse, I feared.

"You have the best job in the world," friends often say. And normally making wildlife documentaries for Discovery Channel is just that. But on that September 2000 night, on top of Toodoggone Plateau in the Spatsizi wilderness, I'd gladly have traded jobs with any Detroit assembly worker.
Ironically, it was the wind that brought us to the high alpine desert in the first place. We had come to this particular mountain to study a species of wild mountain sheep named Stone sheep, who survive where few others can because of the wind.

In a land held by winter for eight months of the year, it is the wind that nourishes the sheep, stripping the snow from savanna slopes and plateaus, exposing grasses and lichen. Mount Toodoggone sits at the junction of four wind-tunnel valleys. Maybe that's why it's prime sheep domain. Wind is the norm, hurricanes the exception.
The top of Toodoggone, high above the surrounding necklace of lakes and valley bottoms, was once ocean floor. In an exposed layer just a metre beneath the top of the plateau, we found deposits of ammonite fossils (giant snails that roamed the seabed 150 million years ago).

The Stone sheep are named after naturalist Andrew J. Stone, who first identified them. They are an example of a fundamental force of evolution: the influence of geology upon the genetics of species.

Stone sheep are one of five species of mountain sheep that inhabit North America. Together with their all-white cousins, the Dall sheep of the Yukon, they form a species called 'thinhorn' due to their delicate, African-style horns.

The bighorn species, as their name implies, have thick, heavy horns. Their range extends from the Rockies to the deserts of Mexico. Although thinhorn and bighorn may share adjacent ranges, they cannot crossbreed.
The evolution of these two distinct species is the result of isolation by ice. During periods of glaciation, the formation of ice drew down ocean levels, exposing land such as the Bering Strait between Asia and North America. It is thought that back some 300,000 years ago, ancestors of the mountain sheep crossed the strait to North America. During the next period of global warming, the immigrants were cut off. In isolation, they became the modern-day 'bighorn'.

Again glaciation shrank the oceans, allowing a second wave of sheep from Eurasia to cross the land bridge. These were the ancestors of the thinhorn. Following a subsequent climate
shift, this band splintered into two groups that evolved independently into the Stone sheep and the Dall.

The story doesn't end there. For though the Dall sheep are the Stone's nearest neighbors, their closest genetic relatives are the Siberian snow sheep in Russia. The theory is that a splinter herd of Stones wandered back to Asia during the last period of glacial advance, only to be cut off again.

In short, Stone sheep show that we can map and date both the direction and the rate of evolutionary change in species by tracing geological events.

Stone sheep are the ugly ducklings of sheepdom. Neither cuddly-cute like the all-white Dall, nor as big as the bighorn, Stone sheep, like a sandlot baseball team, come in a vast array of uniforms. They can be gray, or black, mahogany brown or bleached blond. They can have elegant horns, deformed horns, and sometimes just one horn - the result of injury rather than genetics.

You can tell the players by their uniforms; this makes them the darlings of scientific studies since you can recognize individuals and follow them through the seasons.

Still, for all of their uniqueness, one of our first discoveries was how many traits Stone sheep share with all mountain sheep. For example, the behavior of rams. There is no critter on the face of the planet more appropriately named than the ram. Contrary to the common belief that head butting happens only during the rut, ramming heads is an intricate part of wild sheep behavior year-round, serving many social functions from beating boredom to keeping wolves away.

Both ewes and rams have horns, but hard ramming is a testosterone thing. It begins soon after birth, and a ram's day is spent ramming his head against anyone else bent on ramming. Sheep society is highly evolved and social status is based upon size. The oldest sheep with the biggest horns get the best beds, grasses and places at the salt lick.

Since they have the speed a deer, the agility of a mountain goat on steep rocky cliffs, and 12- to 20-kilogram weapons anchored to their foreheads, healthy wild sheep are not easy prey.

In fact, I believe the main killer of Stone sheep is sex! During the rut, Stones practice ritual behavior which can only be described as bizarre, even by human standards. Besides the head banging, Stone sheep sex is a marathon sport, like a dog race, with the ewe as not-so-reluctant rabbit. At any one time there can be as many as a half-dozen suitors chasing her. It is a brutal sport; rams continually slam into each other, and many drop out early.

For roughly a month, Stone sheep rip around the slopes chasing each other like preschoolers on the playground. But they also violently attack each other like gangs in a turf war. It's late fall when it is over. Everyone is exhausted, often hurt, and winter and wolves take a heavy toll.

A question we asked while making the documentary was how the Stone sheep survive -75° wind-chills. Under an electron microscope at the University of British Columbia, we discovered the answer lies in the hair.

Their coats are composed of two types of hair, a long guard layer woven through a short fleece-like layer. But the secret is what's inside each hair. The microscopic images revealed that each follicle is a lattice of tiny chambers which are individually wind-resistant, waterproof thermo-units. With this protection, the temperature difference between the inside of a sheep's body cavity and the outside environment - just three centimetres away - can be almost 100° C!

Still, for all we learned about Stone sheep - such as their use of range, behavior, and of course their rituals (bizarre and otherwise) - our most striking observation was how well they are adapted to living on the narrowest of margins in the north, and, in comparison, how poorly we are.

There is a point beyond fear when you resign yourself to your fate and slip into a state of peaceful acceptance. Eventually, even the explosive blasts of wind tearing at my tent no longer affected me.

With the dawn the wind relaxed. I was on an adrenaline high. Cas was just as alive, his camera was rolling as I climbed out of the side of my tent. Our camp looked like it had been cluster-bombed, except for Cas' tent. He had the foresight and ability to collapse it during the night. My tent, however, looked like an angry porcupine, with shattered poles sticking out from their shredded sleeves. The cook-tent was split by two ceiling-to-floor tears. Summer ventilation, we smiled halfheartedly, since it was early September with a lot of winter filming to go.

Over our short career as filmmakers we've awoken many times to fresh snow. Once an upwind, self-absorbed grizzly would have walked over Cas, his brother Stan, and our camera (still rolling) had he not been asked to leave, which he did in sheer terror. We've had more than a few anxious moments on the end of climbing ropes. Still, all in all, it is a great job, and I've put on hold, at least for the moment, a career on the assembly line.

(Monty Bassett and Cas Sowa are northwest filmmakers. Their movie Sheep Of Stone is the second episode of a three-part series about northern animals living in impossible settings. Their first documentary Life On The Vertical won the Best Science Award at the Canadian International Documentary Festival, as well as a Gemini nomination. Sheep Of Stone is scheduled to air Friday, Nov. 22, on Discovery Channel.)
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