Experts fear only three of South Selkirk herd, which moves from Canada into Idaho and Washington, survived winter – all female

The last remaining herd of caribou to roam the contiguous United States is believed to be on the brink of disappearing, after an aerial count suggested that only three members survived the winter – all of them female.

The South Selkirk herd were once part of a larger population of southern mountain caribou whose habitat spanned much of the Pacific North-west. But human activity – from hunting to logging and snowmobiling – has forced the population to break off into small herds.

By 2009, the Selkirk herd was estimated to have about 50 members, living in an ecosystem that stretched from British Columbia to Washington and Idaho.

Seven years later that number had dwindled to 12, despite decades of efforts to save them. This week, biologists with the provincial government of British Columbia suggested just three members of the herd remained.

“In the absence of extreme measures, the herd is functionally lost,” said Candace Batycki of the Yellowstone to Yukon Conservation Initiative. “There are only three females remaining – we don’t know if any of them are pregnant. It’s a pretty dire situation.”

We’ve jeopardised their habitat over the last 30 to 40 years through unsustainable rates of logging Mark Hebblewhite, biologist

For decades conservationists have worked to bolster the Selkirk herd’s numbers by transplanting other caribou into the herd, controversially culling wolves and banning logging and snowmobiling along large swaths of the herd’s range.

It wasn’t enough. “It’s one of those things that’s a shock but not a surprise,” said Batycki, whose organisation is calling for an immediate moratorium on industrial activity in the southern mountain caribou’s critical habitat.

“This herd was kind of besieged, if you will, for decades. When you get down to a dozen or fewer animals, maybe it’s just one avalanche that takes most of them out. They’re just so vulnerable at that point.”

Weighing as much as 600lb, mountain caribou feed on a slow-growing lichen that relies on centuries-old trees to develop, putting them at odds with the settlers who first chopped down old-growth forests to develop the land, and later, the logging industry.

“We’ve really jeopardised their habitat over the last 30 to 40 years through unsustainable rates of logging,” said Mark Hebblewhite, a Canadian wildlife biologist at the University of Montana. “It’s all about habitat. You can do everything you want; you can kill wolves, you can kill invasive predators, you can kill species like moose … but without habitat what you’re doing is just buying time.”

He said the loss of the Selkirk herd was an example of the failure of the Endangered Species Act in the US, catapulting Canada into its first major test of its international commitments to protect biodiversity.

“The bigger picture is that this is happening across Canada,” Hebblewhite said, citing caribou populations that have effectively disappeared in Quebec, Ontario and Alberta in recent years.

Half of Canada's monitored wildlife is in decline, major study finds Read more

“This is really the legacy of 30 years of mismanagement of habitat and that we will continue to see more and more extirpations unless both the provincial and federal governments actually get a bit more serious about caribou conservation.”

Many of those that remain are rapidly shrinking in size, Hebblewhite added. “Across the country there’s over 60 caribou ranges. Seventy percent of them are declining. Some of them in Alberta are declining 50% over eight years.”

A recent estimate by Canadian officials suggested the number of southern mountain caribou in the country now hovers around 3,800, down from 5,800 in 2014.

While British Columbia ranks among the provinces that is doing the most to protect caribou, what they are doing is far from enough, Hebblewhite said. “That’s how big the problem is. We’ve logged a lot of these places so much that it’s going to take a long time for these forests to turn back into caribou habitat,” he added. “And continuing to log just undermines everything else they’re doing.”