12.2: Animal Armageddon

“At least 1 million plant and animal species of the estimated eight million known are now at risk of extinction,” summarizes Eric Stokstad (2019) of the report from the Intergovernmental Science-Policy Platform on Biodiversity (IPBES) issued in May of 2019. The report follows an announcement by the Living Planet Report the previous fall, informing us of “an overall decline of 60% in the population sizes of vertebrates between 1970 and 2014—an average drop of well over half in less than 50 years” (World Wildlife Fund, 2018). And it was followed by another shocker, a report that nearly 3 billion birds—representing almost a third of bird abundance in North America—have been “lost” from ecosystems over the last 48 years (Rosenberg et al., 2019). The recent news of how severely our collective human activities have impacted other lifeforms on this planet has been a rude awakening for many of us, but alas, a dip into the recent scientific literature assures us that it is true.

On a scientifically conservative estimate, we humans have already brought about the extinction of almost 500 species of vertebrate animals since 1900 (Ceballos et al., 2015); these scientists found that “the evidence is incontrovertible that recent extinction rates are unprecedented in human history and highly unusual in Earth’s history,” leading them to conclude that “our global society has started to destroy species of other organisms at an accelerating rate, initiating a mass extinction episode unparalleled for 65 million years.” The total number of species already declared officially extinct may not sound that alarming, however, until the number of species, vertebrate and invertebrate, that are now considered to be somewhere along the way—officially “threatened” with extinction in the near future—is revealed: it was around 28,000 in 2019—27% of over 100,000 assessed species–and includes, for example, 25% of all mammals, 14% of all birds, and 40% of all amphibians (IUCN Red List, 2019). The “1 million at risk of extinction” reflects the fact that more than 500,000 terrestrial species now “have insufficient habitat for long-term survival” and thus “are committed to extinction,” many of them within the coming decades unless significant habitat restoration is carried out and other threats defused quickly (Diaz et al., 2019, p. 13)

High levels of vertebrate population decline and loss are found across the tropics, and are especially prominent in the Amazon, central Africa and south/southeast Asia. The ‘proximate’ drivers of the descent toward extinction—the immediate threats responsible for taking out a species—include overexploitation (direct killing by humans), habitat destruction through land conversion and fragmentation, invasion by introduced species and disease, toxification from pesticides and other pollution, and now, increasingly, climate change (Dirzo et al., 2014). The “ultimate” drivers of these trends, however, are just about always some combination of continuing human population growth and increasing per capita consumption (Ceballos et al., 2017). Overexploitation of wildlife now takes the form of the ‘bushmeat’ trade—now including the taking of animal body parts to sell on the world market—in many tropical countries around the world, as what may have once been the ‘sustainable’ hunting of wild animals for meat has “metamorphosed into a global hunting crisis” that now threatens “the immediate survival” of over 300 species of mammals as well as other kinds of wildlife (see Ripple et al., 2016a), a problem that will be considered in more detail in Section here.

Focusing on extinction per se is misleading, however, because it obscures the fact that an actual extinction is usually the result of a long period of loss of organisms from local populations and loss of populations from the landscape that eventually adds up to the disappearance of the species altogether. While extinction results in a permanent loss of biodiversity from the planet, moreover, population declines and alterations in species composition contribute to alterations in ecosystem function that can cascade throughout ecosystems in nonlinear fashion (as will be discussed in the following section). In 2017, Gerardo Ceballos, Paul Ehrlich and Rudolfo Dirzo reported on the “biological annihilation” that’s happening with increasing rapidity now, as numbers of individual animals shrink and populations diminish. Examining data for a sample of over 27,000 species of terrestrial vertebrates—nearly half of known vertebrate species—they found that around a third are experiencing significant population losses, both in numbers and in range size; moreover, almost half of the 177 species of mammals they examined have lost more than 80% of their geographical ranges since 1900, and all of them have lost at least a third. Most shocking of all, however, is their estimate that “as much as 50% of the number of [vertebrate] animal individuals that once shared Earth with us are already gone” (Ceballos et al., 2017). And a look at biomass ratios really brings home the massive scale of our growing human footprint, and what it is doing to our evolutionary cohorts within the Biosphere. Yinon Bar-On, Rob Phillips, and Ron Milo (2018) estimated the total biomass of all living wild mammals (terrestrial and marine) today to be, in round numbers, only about 0.006 gigatonnes of carbon (GtC), while the biomass of all the humans on the planet—more than 7 and a half billion of us–is .06 GtC, and that of all livestock (dominated by cattle and pigs) is 0.10 GtC; in other words, the total biomass of all the wild mammals on Earth is equal to only about four percent of the total biomass of humans plus their domesticated food animals. When the biomass of great whales and other marine mammals is excluded, moreover, the biomass of wild land mammals is estimated to be about 0.003 GtC, or about five percent of the biomass of humans alone, and less than two percent of the biomass of us humans and our livestock taken together. The impact of our human species on other forms of life has thus been truly staggering.

Characteristics that tend to make a species more vulnerable to diminution and eventual extinction include large body size, low reproductive rate and large home range requirements, especially when the existing habitat range is small, making many of the “terrestrial megafauna” severely threatened (see Ripple et al., 2016b, 2017). You can take almost any large-bodied wild mammal you’ve ever heard of and chart an ominous decline. Franck Courchamp and colleagues (2018) discovered that there is still very little public awareness of the dire straits of many of their favorite animals; recapping the little-known situation with our “charismatic megafauna,” tigers have been knocked down to less than seven percent of their historical levels in the wild, lions to less than eight percent, and elephants less than 10%; three of four giraffe species have experienced declines of over 50%, one more than 90%, leopards have lost up to 75% of their range, with only three percent of the original range remaining for six of nine subspecies, and cheetahs have been extirpated from 29 African countries, remaining on only nine percent of their historic range, while two gorilla subspecies have dwindled to a few hundred individuals and populations of the other two have plummeted to less than half what they were over the last 20 years.

While habitat loss has been steadily reducing populations across the board, these authors report that, when killing for bushmeat, trophy hunting and conflicts with humans are considered together, direct killing by humans is responsible for the greatest number of them being endangered overall; they estimate, for example, that “unsustainable bushmeat hunting, trophy hunting, habitat loss and human conflict all combine to make most of African lion populations surviving the next few decades unlikely” (Courchamp et al., 2018, S2). Elephants and rhinos are being slaughtered mercilessly for their ivory and their horns across Africa, and even giraffes, which have declined by 40% over the last 20 years, are in part falling prey to the trade in their highly prized tail (see Chase et al., 2016; Gibbens, 2018; and Daley, 2016, respectively). Polar bears, who typically support themselves almost exclusively by preying on seal pups emerging from crevices in the sea ice, and as the ice thins and melts, they will inexorably starve unless they learn to consume land-based prey (Whiteman, 2018). Killer whales, once abundant in the oceans, are now estimated to count only in the tens of thousands, with many populations declining as a result of a reduction in salmon and other prey, disturbance by boat traffic, acoustic injury from sonar used in naval exercises and underwater exploration, and toxic effects of oil spills and other pollution; more than half of their populations are thought to be at high risk of “complete collapse” over the next century from the bioaccumulation of polychlorinated biphenyls (PCBs) in their tissues (Desforges et al., 2018).

Among our closest evolutionary relatives, 60% of primate species are threatened with extinction “because of unsustainable human activities,” while 75% of primate populations are decreasing globally (Estrada et al., 2017). Chimpanzees are officially classified as “endangered,” and all gorillas are now listed as “critically endangered,” while the tiny mountain gorilla population is holding on at less than 500 individuals (Gray, 2013). Bonobos are also classified as “endangered,” with an estimated population of 15,000 to 20,000 individuals (Fruth et al., 2016); disturbingly, their entire range is contained within the lowland forests of the Democratic Republic of Congo, the largest country in sub-Saharan Africa and one that is subject to out-of-control slaughtering of wildlife for “bushmeat,” ^[2] as well as increasing habitat fragmentation, warfare, and the rages of an ebola epidemic, to which great apes are susceptible. Meanwhile, the fourth great ape, the orangutan, may be hurtling toward extinction the fastest of all, with over 100,000 killed in Borneo between 1999 and 2015, cutting the population by more than half, leaving an estimated 70,000-100,000 there plus less than 14,000 in Sumatra; all orangutans are now listed as “critically endangered,” by expanding palm oil plantations as well as hunting in primary and selectively logged forests (Voigt et al., 2018).

Pangolins—a little-known, shy, nocturnal mammal described as resembling “an artichoke on legs” that, when threatened, rolls itself up in a scale-covered ball sufficient to protect it from all natural predators but not, unfortunately, from its human enemies—are being devastated by a burgeoning trade in their meat, skin and scales; after China’s population of pangolins was reduced by 94% since the 1960s, poaching of pangolins in Africa has reportedly increased by 150%, with as many as three million now being removed annually from Central African forests, most of them bound for China (Ingram, 2018); pangolins are being considered a “probable animal source” of the coronavirus outbreak that has now become a global pandemic (Cyranoski 2020); Sonia Shah points out that many zoonoses now affecting the human species are the result of our accelerating invasion of natural habitats for live animals and their parts to sell in so-called “wet markets” (Shah, 2020), as will be discussed further in Section here.

Hundreds of thousands of seabirds suffer high mortality as “incidental catch” in drift nets, purse seines, gill nets, traps, trawls and longlines, while wind turbines have been estimated to kill more than 400,000 birds a year, communication towers over six million, and domestic cats between 1 and 4 billion in the US alone (White, 2013), even as millions are being shot while migrating over Europe “for food, profit, sport, and general amusement” (Franzen, 2013; Margalida & Mateo, 2019). Meanwhile, hundreds of thousands of wading birds have been destroyed by the closing off of the Saemangeum tidal flat by South Korea in 2006, described by Michael McCarthy (2015, pp. 66-68, 81) as “the biggest destruction of an estuary that has ever taken place,” “a giant engineering vanity project” and “one of the most egregious examples of environmental vandalism the modern world can offer”; the number of shorebirds using the flat are down by as much as 97% (Lee et al., 2018), and worse yet, 50 million wading birds using the East Asia/Australasia Flyway for their twice-yearly migration are at risk from escalating habitat destruction all along the Chinese and Korean coast of the Yellow Sea, their precipitously declining numbers already indicating “a flyway under threat” (Piersma et al., 2016). The Helmeted Hornbill, another notable bird species, was put on the “Critically Endangered” list in 2015, not only for rapidly dwindling habitat but also because demand is growing for the “red ivory” of its “casque,” which is carved into handicrafts for Chinese markets, ^[3] something that was recently decried in the journal Science (Li & Huang, 2020). And, unbeknownst to many ardent admirers of Irene Pepperberg’s late Alex, the celebrated African Grey Parrot is also now in danger of extinction. African Greys used to inhabit more than a million square miles across West and Central Africa, but because of the international pet trade—the African Grey is the single most heavily traded wild bird, according to CITES, the organization that regulates global wildlife trade—it is believed that more than a million of the birds were taken from the wild over the past 20 years. Ghana reportedly has lost 90-99% of its African Greys since 1992 (Annorbah, 2015); as populations are wiped out in Ghana, Tanzania, Uganda, Rwanda and elsewhere, birders are recognizing “the African silence” (Steyn, 2016).

Reptiles are included in the global decline, while amphibians are seriously threatened worldwide by the chytridiomycosis panzootic that is affecting over 500 species, causing the presumed extinction of at least 90 of them over the past half-century, the greatest loss of biodiversity attributable to a disease ever recorded (Scheele et al., 2019). Large fish in the oceans have reportedly dropped in numbers by over 90% (Myers and Worm 2003, SeaWeb 2003), with some species, such as cod and some tunas, falling by as much as 99%, and it has been noted that only 37% of shark species are not threatened with extinction, with up to 100 million sharks being killed every year for the global trade in shark fins, the major driver of their road to extinction (Sadovy de Mitcheson et al., 2018). And populations of mobulid rays–manta and devils rays, now known to be highly social and intelligent but also very slow to reproduce, with only one offspring every three years or so —are plunging, largely due to the growing Chinese market for their gill plates, erroneously believed to “clean impurities” when ingested but actually containing high levels of cadmium and arsenic (Guardian, 2014). They are also suffer high mortality as “incidental catch” in drift nets, purse seines, and other technologies of industrial fishing.

The dire straits of many more of our fellow members of the Biosphere could be recounted here, but perhaps it is more pertinent to ask how it is that even the well-known mammals—the ‘charismatic megafauna’ so prominent in our human imaginations—could be under such assault without it having come to our global attention long before this. How could we have missed it? This question is explored by Franck Courchamp and his colleagues (2018). They identified “the 10 most charismatic animals”: the tiger, the lion, the elephant, the giraffe, the leopard, the panda, the cheetah, the polar bear, the gray wolf and the gorilla, all but one of which are either vulnerable, endangered or critically endangered, and discovered, that fully half of people asked in surveys were not informed about their conservation status. Volunteers were then asked to document every encounter with one of these 10 animals in advertisements, entertainment, logos and so on, and they reported seeing as many as 30 individual images of each of the 10 species over the course of a week, corresponding to several hundred encounters per month; lions, for example, were seen at an average rate of 4.4 images per day, “meaning that people see an average two to three times as many ‘virtual’ lions in a single year than the total population of wild lions currently living in the whole of West Africa.” They concluded that “the public perception of the conservation status of these species appears to reflect virtual populations rather than real ones” (Courchamp et al., 2018), masking the real extinction risk, and they have proposed that companies benefiting from using images of these (and other endangered) animals in their marketing pay a fee to be spent directly on conservation efforts benefiting these animals. But, meanwhile, our War Against Nature continues to take its heavy toll.