The Human Face of Species Loss

I recall hearing on the radio on October 31, 2011, that, according to the United Nations, world population had just reached 7 billion. I then went online to get details, and discovered Index Mundi – a data portal that turns facts and statistics into easy-to-use visuals. Since that day, the number of people on our planet has risen by another ten percent, and now increases by about 135 infants per minute. 

This vast and exponentially growing change in human population has fundamentally changed the biomass on our planet. Livestock (mostly cattle and pigs) now represent 60 per cent of the world’s mammals; people, 36 per cent; wild mammals, four per cent.

Over the last half-billion years, there have been five mass extinctions, when the diversity of life on earth suddenly and dramatically contracted. Scientists around the world today are monitoring a possible sixth extinction, predicted to be the most devastating extinction event since an asteroid crashed into Earth, famously wiping out the dinosaurs, but also countless other flora and fauna.

Birds and Citizen Science: This helps explain a dilemma facing humankind. As I suggested in a Critica commentary titled This is for the birds, I am one of a vast tribe of people around the world who get considerable enjoyment from birding – bird-watching to the uninitiated – and contributing in my small way to global databases about the health of our world’s avian populations.

For example, during the vast North American bird migration last spring, I was part of a group of 14 birders from Calgary who spent five days at Writing-On-Stone Provincial Park – so named because of ancient Indigenous carvings on local cliffs – to do five days of birding. The areas we explored were near Milk River – little more than a creek in that area, which originates in Montana, turns south and joins other streams running south. Eventually, its waters flow into the Mississippi.

The purpose of our visit was to count the number of species present in a few well-defined regions at the border between Canada’s province of Alberta and the American state of Montana. By foot, at least, we could cross these open borders at will. However, we stayed on the Canadian side of the border, and spent those days identifying species and counting the numbers the individual birds in each species. We then submit detailed reports – a dozen of them in all – to Cornell University’s eBird website – a network the school launched in conjunction with the National Audubon Society in 2002.

This site accumulates and produces geographical data on birds throughout the year and around the world. Based in Ithaca, New York, Cornell also helps maintain a fleet of birdcams positioned to video active nests. This enables the curious to observe birds around the world raising their young.

Increasingly the centre of the ornithological world, eBird enables birders and ornithologists to record and enumerate bird populations from every habitat. Enthusiasts like our small band do bird counts within given geographical regions. Like others on our expedition, enthusiast Jennifer Solem was passionate about the value of these expeditions. “I fear bird counts may become very important for identifying the effects of floods and now, again, fires in crucial boreal breeding areas.” She was hopeful, she said, that the data emerging from bird counts could serve as “motivation for prioritizing conservation in [forest] habitat.” For birds and other species, habitat is everything.

For ornithology as much as the birds it studies, the issue is more serious in the densely populated places in the world than in the vast, sparsely populated provinces of Canada. That said, the eponymous Canada warbler – a bird that delights for both its appearance and its song – is one species at risk in North America. These warblers mostly breed within Canada’s boreal forest and winters along the northern edge of South America, where diversity is more than fifty times greater than in all of this country’s boreal forests. The species is at risk because of the loss and degradation (through logging) of old-growth deciduous forests in Canada, combined with further habitat degradation in its wintering regions.

In Canada, efforts to save threatened species are failing. Of the more than 700 plants and animals currently listed under the Federal Government’s Species at Risk Act, most are losing ground at an alarming rate. According to World Wildlife Canada, on average those species have declined by another 28 per cent since the act came into effect in 2002. So, is being listed for federal protection a rescue operation or a recommendation to enter a ward for incurables?

The act requires the Canadian Government to protect listed species, but does not offer best practices on how to do so. Nor does it advise conservation groups on what to do when confronted with competing needs. With so many species in peril, and limited funds available, Canada’s conservation efforts to date look like a patchwork of measures guided as much by intuition and chance as by science.

A Global View: Internationally, one in every eight bird species faces possible extinction, according to a riveting recent report by Birdlife International. Calling bird life “nature at its most enthralling,” the report describes birds as “one of the best known and most highly valued elements of the natural world.” They comprise more than eleven thousand different species, “ranging from hummingbirds to ostriches, from penguins to eagles.” Each species is unique in appearance, habits and habitat. Some still occur in vast flocks, while others are now down to a few remaining individuals. Some spend their entire lives within a few hectares of land. Others undertake annual migrations that cover half the world.

A couple of dozen species and subspecies have economic value as food and for their feathers. They range from geese to chickens to pheasants. Birds also have some surprising uses. For example, in parts of South Asia, some swiftlet nests – constructed almost entirely of saliva, with little or no plant material – are used to prepare a highly prized soup consumed by men who believe it is an aphrodisiac. Also, of course, such species as parakeets and cockatoos are often sold as pets. Like livestock, such birds are not at risk.

With those bits of knowledge under my hat, I drove down with the expedition’s de facto organizer, a long-time friend named Dave Russum. We talked about the not-too-obvious reality that the days are now long gone when you were likely to drive along rural roads and find your windshield covered with the remains of bugs.

A geologist by training, Russum reminded me that “The first insects on earth evolved about 400 million years ago while birds, as we know them, first evolved about 60 million years ago. Insects were therefore well established around the globe when birds showed up.” For many bird species, they were an obvious food source. He added that many species are “only reliant on insects for part of the year.”

Such species as swallows and flycatchers, however, “are dependent on insects for most of their nourishment, not just on their breeding grounds and wintering grounds, but also during their migration in the spring and fall.” If natural habitat and the associated insects are destroyed over a significant area, many of the birds dependent on those insects cannot survive. “Their populations will rapidly decline.”

I reflected on that a bit. When I left Toronto for Calgary in the 1970s, the car that reached this city was a mess, with splattered bugs covering the windshield. I can’t remember when I last noticed such a thing, even after a long drive into rural Alberta. The reason is that the absolute number of insects (not species) on our planet is in rapid decline, from Arctic to Antarctic, and virtually everywhere in between.

There are so many fewer bugs in the system because of habitat lost to urbanization, intensive agriculture and, to some degree, the use of pesticides. But in addition to the lost numbers of insects, some 40 per cent of insect species face out-and-out extinction.

Why is that important? Animals, mostly insects, pollinate 87% of flowering plants, according to a commentary in The Economist. “Without insects, most plants could not reproduce. They break down and recycle the nutrients that plants need for photosynthesis. They decompose organic waste and feed a large proportion of all birds and bats.”

In terms of the number of species, insects are by far the most abundant life forms. They are so numerous that they contain three times as much mass as humans and 30 times that of all wild mammals. There are more than one million insect species, compared to some 6,000 varieties of mammal, and 18,000 classes of bird.

Insects live in almost every habitat on the planet – on all five continents, in lakes and rivers, seas and oceans, sloughs and deserts. And they are vital contributors to the food chain everywhere. Mammals, birds, fish, reptiles and insects themselves can all be wholly or partly insectivores. The rapid decline in these food sources is contributing to rapid declines in other species of many types. And that brings me back to the likelihood of yet another mass extinction.

Sixth Extinction? Five vast extinctions – called “the big five” by earth scientists – have challenged life on earth during the past 500 million years. The best known of these was a sudden mass extinction of some three-quarters of the plant and animal species on Earth approximately 66 million years ago – famously killing off the dinosaurs, but also many other species. It marked the end of the Cretaceous period and with it, the entire Mesozoic Era, opening the Cenozoic Era that continues today.

It now turns out we may be at the beginning of a sixth, according to a United Nations report titled 2019 Global Assessment Report on Biodiversity and Ecosystem Services. For three years, hundreds of scientists contributed to the project. They concluded that as many as a million species planet-wide are on the brink of extinction.

The UN study of this problem would certainly have considered the content of a 2014 book by Elizabeth Kolbert. The author tells us why and how human beings have altered life on the planet in a way no species has before. Interweaving research in half a dozen disciplines, descriptions of the species that have already been lost, and the history of extinction as a concept, Kolbert provides a moving and comprehensive account of the disappearances occurring before our eyes.[1]

“In what seems like a fantastic coincidence, but is probably no coincidence at all,” she writes, “the history of these events is recovered just as people come to realize they are causing another one.” She suggests that the sixth extinction is likely to be mankind's most lasting legacy to our planet, “compelling us to rethink the fundamental question of what it means to be human.” We are affecting planetary systems in many ways, and have been doing so every moment for centuries.

Kolbert cites a paper by researchers from McGill University and the University of Maryland which describes the world’s “anthromes” – also known as anthropogenic biomes or human biomes. These are the globally significant ecological patterns created by sustained interactions between people and the world’s ecosystems. Once you add up the total area covered by these systems, there are only eleven million square miles of space left on the planet. “These areas, which are mostly empty of people and include stretches of the Amazon, much of Siberia and northern Canada, the Sahara, the Gobi and the Great Victoria deserts, they call the ‘wildlands.’”

It is certain that something big is underway. The best estimates are that Earth is losing species at many times the background rate – the natural churn in which a few species go extinct every year while new ones evolve. Between 30 percent and 50 percent will be functionally extinct by 2050. “Right now,” humankind “are deciding, without quite meaning to, which evolutionary pathways will remain open and which will forever be closed. No other creature has ever managed this, and it will, unfortunately, be our most enduring legacy.”

Perhaps the best way to conclude this discussion is with quotes from two renowned scientists, whom she mentions in her closing patients. One is anthropologist Richard Leakey, who said that “Homo sapiens might not only be the agent of the sixth extinction, but also risks being one of its victims.”

The other is Stanford ecologist Paul Erlich. “In pushing other species to extinction,” he wrote, “humanity is busy sawing off the limb on which it perches.”