One Number Tells a Shocking Story about Wild Mammals

Just a 30-minute drive from the expanding megalopolis of Calgary lie the eastern foothills of Alberta or what’s known as the upper Bow River basin.

The basin, thanks to the presence of numerous federal and provincial parks, contains a remarkably diverse landscape of mountains, forests and grasslands. This land, in turn, supports what Alberta-born land-use ecologist Brad Stelfox calls a “Serengeti of mammals.”

Few urban centres containing 1.8 million people can boast a patch of wildness in their front yard that still nurtures grizzly bears, elk, moose, deer, cougars, black bears, weasels and bobcats — a total of 19 mammal species.

“I know of no other circumstance where such a diversity of predators and hoofed mammals can be found 30 kilometres from a major urban centre,” said Stelfox.

But with provincial plans to double Alberta’s population to 10 million people by 2050, Stelfox wonders how long that Serengeti will persist. In fact, he considers the upper Bow River basin to be a telling metaphor for the province’s ecological health and the state of its wildlife.

Although the 15,000-square-kilometre watershed still delivers much clean water, biodiversity and spectacular scenery, those debased services continue to be eroded by urban encroachment, logging, agriculture, roads, gravel mining and excessive motorized recreation.

Basin wetlands, essential for protecting water security and quality, have declined from 560 square kilometres in the 1800s to 295 square kilometres in 2010. Grasslands essential for elk and deer and their predators have shrunk by more than 50 per cent. By 2060 one-fifth of the basin will be re-engineered and industrialized by humans for more humans.

So Stelfox asked himself a question: Does the state of wild mammals in Alberta reflect global trends of rapidly declining wildlife diversity?

And what he found was “a holy moly moment.”

Although Alberta still offers some of the world’s most stunning scenery, few people realize how wild mammal populations (and their habitats) have declined over the last 300 years since the first Europeans arrived.

Most Canadians still believe the country to be so enormous that wild creatures remain much more abundant and diverse than anything people can create or consume with machines.

Yet these notions do not reflect reality and have been debunked by recent studies that looked at the weight and size of living things on the planet.

In 2018 Israeli researchers, for example, added up all the biomass on Earth. Plants outweighed everything else, followed by bacteria, fungi and viruses. Marine mammals then outweighed land-based creatures. And so on.

But humans and their domesticated livestock now dwarfed wild mammals. And humans had reduced total plant biomass by twofold relative to its value before civilization.

Two years later the same Israeli researchers compared the weight of all living things with human-made stuff. They concluded that humans and their infrastructure made up three per cent of global biomass in 1900. But by 2020 civilization’s relentless assembly of asphalt, concrete, steel, bricks and plastic exceeded the mass of all living things including plants and was on track to triple its size by 2040. Man-made stuff now outweighed all living things in the biosphere.

The fate of mammals illustrates the scale of this epic transformation.

In 2022 the data scientist Hannah Ritchie used the Israeli data to calculate how humans have pummelled the wild mammal kingdom over the last several centuries.

Wild mammals — everything from elephants to bison — once walked the Earth sustaining critical nutrient flows. But with the rise of humans some 100,000 years ago, their diversity and population began to shrivel.

The eradication accelerated after 1900 as humans transformed the world with fossil fuels. Wild mammals now represent a puny four per cent of the biomass of mammals on Earth.

Three things happened: Populations of large wild mammals plummeted as humans destroyed their habitat. Then hordes of a select group of domesticated mammals took their place.

If you subtract whales from the equation, the figure actually drops to two per cent.

Today, humans and their livestock, including pigs, cows and horses, comprise the majority of living mammal biomass — a remarkable 96 per cent.

This startling replacement of wild mammal biomass by a handful of species prized by humans has changed everything from land-use patterns to biological diversity to disease outbreaks.

To Stelfox, who can rhyme off most wildlife species by their Latin names and has studied land-use changes in Alberta most of his life, Ritchie’s findings were “a mind-blowing observation.”

He then wondered how Alberta’s wildlife, including wild creatures inhabiting the upper Bow, have fared against these global trends. He had the tool to do the job: a cumulative effects computer model that he helped to design called ALCES.

“In my heart as an Albertan, I had thought we would be comparatively less developed and have more of our native mammal biomass remaining,” reflected Stelfox.

That’s not what he found.

Stelfox used his model to subtract cities, roads and all modern paraphernalia and return to habitats occupied by bison and some 50,000 Indigenous people 300 years ago. He then estimated what kind of wildlife numbers those functioning landscapes could sustain. He compared the past with the current biomass of humans and mammals occupying modern Alberta.

He roughly estimated that in pre-European times, there was about one billion kilograms of wildlife, primarily bison, elk, moose and pronghorn, and about three million kilograms of humans some 300 years ago. The flow of wildlife biomass (think vast herds of bison), not people, dominated the landscape. In fact, humans represented but half of one per cent of the mammal biomass.

But over the space of 300 years the natural world shrank or was destroyed. Now wildlife represents but 3.8 per cent of all mammal biomass while humans (4.8 million Albertans) make up 12.8 per cent of the biomass. In other words, Alberta has lost 92 per cent of its native mammal biomass while humans and their livestock and pets have increased 701 times. European livestock have replaced millions of bison, elk, pronghorn and deer. And in even greater numbers.

So wildlife in Alberta appears to have been depleted on the same scale as global trends, says Stelfox. “The patterns are very similar.”

Meanwhile overall mammal biomass in Alberta has grown 2.2 times but in the form of humans, cattle, horses, pigs and pets. In fact, the fraction of livestock dominating the landscape in the province greatly exceeds Ritchie’s global average of 62 per cent.

Pets alone in Alberta now weigh 136.8 million kilograms. That’s a biomass 56 per cent greater than the weight of Alberta’s remaining wildlife (87 million kilograms).

When Stelfox relayed his findings at a recent public talk in the hamlet of Bragg Creek, many in the audience expressed shock. “They were dumbfounded that wild mammals make up such a small number and that 92 per cent of the biomass has disappeared since European times.”

But with plans to accelerate Alberta’s human population growth to 10 million, Stelfox suspects that Calgary could well lose the Serengeti at its doorstep and other remnants of the province’s once vast and diverse mammal wildlife.

The wildlife subtractors are well known: wetland destruction; urban growth; fragmentation of wild lands by energy infrastructure; the loss of native grasslands to industrial crop production; roads; and the consumption of landscapes by multitudes of recreationists.

Even if the province were to impose and adhere to best land-use practices, these reforms would not arrest the decline without a corresponding reduction in human numbers or restrictions on human movement in certain landscapes.

“If we are going to feed, employ and house millions of more people, we are going to see a proportional loss of what’s left in the 3.8 per cent,” Stelfox said.

Meanwhile every person on Earth, on average, generates a pile of engineered stuff that now weighs more than their own body weight every week.

This partly explains why the Living Planet Index now records a 69 per cent decrease in monitored wildlife populations including mammals since 1970.

Albertans are doing their part, according to calculations by Stelfox. He concludes that, per capita, Albertans consume more natural resources and generate more waste than 99.9 per cent of all people on Earth.

In the last 12 months alone, Alberta’s population grew by 4.41 per cent: that’s more than 200,000 people.

To Stelfox the message is obvious: “We cannot continue to have more people consuming more stuff and doing so everywhere all the time.”