AN EMPTY LANDSCAPE

AFTER MORE THAN A MILLION YEARS ON EARTH, CARIBOU ARE UNDER THREAT OF GLOBAL EXTINCTION. THE PRECIPITOUS DECLINE OF THE ONCE MIGHTY HERDS IS A TRAGEDY THAT IS HARD TO WATCH — AND EVEN HARDER TO REVERSE.

- ALANNA MITCHELL

CARIBOU MAKE DO. They use as little as possible, often what nobody else wants. They perfected this impulse over tens of thousands of years, chasing north after retreating ice sheets while most other hooved animals stayed further south, or spreading themselves thinly across scraps of land in forests and valleys and on mountaintops.

They even learned how to survive the privations of winter by subsisting on lichen. Platter-sized hooves — ersatz snowshoes — support them on the snow to reach it on high. Shovelshaped antlers help some of them dig snow craters to find it down low.

But getting to the lichen is only part of the survival trick. Caribou also need to squeeze every last bit of nutrition out of the protein-poor food, which means they had to figure out how to reuse their own urea, a chemical byproduct of metabolism, a little like us being able to drink the same cup of coffee twice to get every smidgen of caffeine out of it. The feat continues to impress evolutionary biologists.

Suffice it to say that Rangifer tarandus is built for survival. Females even limit themselves to the birth of a single calf each year, the better to husband resources.

Yet today, after more than a million years on Earth, the caribou, also known as the reindeer, is under threat of global extinction. In Canada, where the animal is such a national icon that it graces our quarter coin, the species is in ominous shape. Of a dozen ecologically distinct populations (called “designatable units” by the Committee on the Status of Endangered Wildlife in Canada), one is extinct, six are endangered, three are threatened and two are of special concern.