The Human Face of Species Loss

The Dodo was just one of many....

The Human Face of Species Loss

By Peter McKenzie-Brown*

On October 31, 2011 I heard on the radio that, according to the United Nations, world population had just reached 7 billion. When I went online for details, I 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. It 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 such event since an asteroid crashed into Earth some 66 million years ago. That episode – the fifth of the big five – famously wiped out the dinosaurs as it obliterated three-quarters of the plant and animal species in existence.

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 group of people around the world who get considerable satisfaction 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 Milk River – little more than a creek in that area, which originates in Glacier National Park in Montana, flows northeast into Alberta, and then turns south and joins other streams running in that direction. Eventually, the waters from these many sources flow into the Mississippi.

We also enjoyed identifying other species. Of the mammals resident in that area we saw, for example, badgers and pronghorn antelope. Along the way, we stopped to see a prairie rattlesnake which had been killed by a car. As it turned out, another was nearby. This species is increasingly rare because of hunting and habitat fragmentation. To give the other rattler a better chance of survival, we chased it away from the road.

But the real purpose of our visit was to count the number of species present in a few well-defined regions near the border between Canada’s province of Alberta and the American state of Montana. We spent those days identifying species and counting the numbers of individual birds in each species in areas which had previous bird-count records. We then submitted detailed reports – a dozen of them in all – to Cornell University’s eBird website – a network the university launched in conjunction with the National Audubon Society in 2002.

This website accumulates and produces geographical data on birds throughout the year from around the world. Based in Ithaca, New York, Cornell also helps maintain a fleet of birdcams positioned to video active nests world-wide. This connects birders anywhere to nests around the world in which species – many of them rare or endangered – are hatching and 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 count birds within given geographical regions. Like others on our expedition, enthusiast Jennifer Solem was passionate about the value of these expeditions. “I feel 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 example, an ornithological study recently compared “blackbirds in Munich with their country cousins,” writes the notable author Diane Ackerman, reflecting a proposal from a group of scientists. In a recent book, she focused on the idea that we are entering a new geological epoch that should be called Anthropocene – a world created by humankind, which is profoundly affecting species that comfortably coexist with humankind. The city birds “adopt a faster pace, work longer hours, and rest and sleep less where upward-showering light washes out the stars and our handmade constellations cluster near the ground,” she wrote. “Urban males molt sooner, and reach sexual maturity faster.” By contrast, rural blackbirds “begin their day traditionally, at sunrise, don’t rush, and sleep longer.”[†]

Many other kinds of species have learned to co-exist in cities with people – deer, for example; cats, foxes, skunks, raccoons, houseflies, sparrows and mice are a few others. Rats exist in most of the world’s jurisdictions (although not in Alberta). Monkeys, of course, are city dwellers in many tropical countries.

Government Studies and Green Technologies: For ornithology as much as for 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. Take the example of the Canada warbler – a bird that delights us for both its appearance and its song, but which is at risk. These warblers mostly breed within Canada’s boreal forest. They winter along the northern edge of South America, where avian diversity is more than fifty times greater than in North America’s boreal forests. The species is at risk in Alberta and other jurisdictions through such human actions as agricultural, urban and residential development and industrial activity. In Alberta, the activity in the energy sector is a threat, but so is timber cutting.

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.

Ironically enough, “green” technologies are actually contributing to the problem, according to a 2010 report from the US government. The use of wind turbines, for example, leads to death by collision with turbine rotors. On the positive side, “fatalities could be fewer because fewer larger turbines are needed to produce the same energy as smaller turbines.”

To put those numbers in perspective, the report observes that wind turbines kill between 214,000 and 368,000 birds annually. That’s frankly a small fraction compared with the estimated 6.8 million fatalities from collisions with cell and radio towers and the 1.4 billion to 3.7 billion deaths from domestic and feral cats.

Of course, the problem of species death is not only about birds. Consider the situation of the only known flying mammals: bats. Like birds, these creatures tend to be migratory. “Bat fatalities peak at wind facilities during the late summer and early fall migration,” according to government report. “Bats are long-lived and have low reproductive rates, making populations susceptible to localized extinction.” Some researchers believe “bat populations may not be able to withstand the existing rate of wind turbine fatalities and/or increased fatalities as the wind industry continues to grow.”

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 requirements. 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.

Most birds that people value are not at risk. A couple of dozen species and subspecies have economic value as food and for feathers. They range from geese to domesticated chickens. Birds also have some surprising uses. Also, of course, such species as parakeets and cockatoos are often sold as pets. However, many of their wild populations are declining due to capture for the pet trade.

Other highly prized birds are at risk, of course. For example, in Southeast Asia, 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. “It's the caviar of the East,” a Hong Kong restaurateur told The New York Times in 1996. “Some economists and conservationists see the pressure on edible bird nests as a symptom of a much deeper problem in East Asia,” the newspaper added. “Rapid economic expansion, population growth and industrialization have created unsustainable demands on natural resources.”

With those bits of knowledge under my hat, I drove down with the expedition’s de facto organizer, long-time friend 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 insects.

A geologist by training, Dave 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 most species need insect protein to successfully rear their young, but can use fruit in their diet for the rest 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 and grill. I can’t recall 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 insects in the system because of human causes. These include 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.

Extinctions: Perhaps one of the greatest causes of decline in insect numbers is the use of electric lights. We have long known that night-flying insects are attracted to a candle. Night-flying insects probably outnumber day-flying ones, ten to one.

Most insects spend a lengthy period as eggs, larvae and pupae before emerging as adults – but then they have only a few days to find a mate and lay eggs, to pass life on to the next generation. When they emerge as adults, they are now attracted to street and porch lights, etc., where they fly around all night. In the morning, exhausted, they cling to those lights, posts or building.

Birds have been quick to find this bonanza of insects. First thing in the morning, they now head for the light source. They can glean the same amount of food within a few minutes, which in the past might have taken most of the day. However, in consuming these newly-emerged adult insects, they are eliminating the source of food – insect larvae – that they need to feed their own young when they hatch. Most of those nestlings are now starving to death. And when the adults die, without any replacement, that bird species becomes extirpated or goes extinct.

The greatest declines in insectivorous birds in North America are in the most densely populated areas – in particular, the eastern provinces and U.S. states.

You almost certainly know about the virtual extinction of bison from North America’s prairies in the nineteenth century, the total extinction of vast herds of passenger pigeons about the same time. Less well known is that the Rocky Mountain locusts once blotted out the sun over the Great Plains. In the summer of 1875, for example, an estimated 10 billion of these insects took nearly a week to pass through Plattsmouth, Nebraska. Twenty-seven years later, the last living specimens were collected on the Canadian prairie. Their extinction was a huge blow to North America’s ecosystems, since they had provided food for countless insectivores.

Why is that important? Animals, mostly insects, pollinate 87% of flowering plants, observes a commentary in The Economist. “Without insects, most plants could not reproduce. They also 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.” If plants don’t reproduce, they disappear – taking with them the nectar and pollen sources that insects need.

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 (perhaps as many as thirty million), compared to some 6,000 varieties of mammal, and 18,000 species and subspecies of bird.

Insects live in almost every habitat on the planet – on all seven 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 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 we are in today.

A recent United Nations report titled 2019 Global Assessment Report on Biodiversity and Ecosystem Services suggests that we are now at the beginning of a sixth. For three years, hundreds of scientists contributed to the project. They concluded that as many as a million species planet-wide may be 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.[‡]

“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.

Citing a paper in which researchers from McGill University and the University of Maryland describe the world’s “anthromes” (also known as anthropogenic biomes or human biomes), she notes that these the globally significant ecological patterns reflect sustained interactions between people and the world’s ecosystems. Once you add up the total area covered by these systems, there are only 28.5 million square kilometres (11 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, she says. 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 “is deciding, without quite meaning to, which evolutionary pathways will remain open and which will forever be closed,” she wrote. “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 Ms. Kolbert notes in her closing pages. “Homo sapiens might not only be the agent of the sixth extinction,” said renowned anthropologist Richard Leakey. Our species “also risks being one of its victims.”

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

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[*] Thanks to Gus Yaki for his comments on a draft of this document. In early 2019, the Governor General (Canada’s head of state, who represents the Queen) conferred upon him the Sovereign's Medal for Volunteers for his efforts on behalf of natural species. 

[†] Ackerman D. The human age: The world shaped by us. HarperCollins Publishers Ltd.; 2014; 114.

[‡] Kolbert E. The sixth extinction: An unnatural history. A&C Black; 2014.