
(Beth Clifton collage)
And why killing dogs, rats, pigs, goats, mice & mongooses too would be mainly make-work for exterminators
SANTA CRUZ, California––Appealing for funding to kill cats, dogs, rats, pigs, goats, and mongooses on at least 107 islands belonging to 34 nations, in the name of promoting biodiversity, the previously obscure 25-year-old organization Island Conservation scored a double coup on March 27, 2019.
First, the appeal concept, a paper entitled “Globally important islands where eradicating invasive mammals will benefit highly threatened vertebrates,” was published by the Public Library of Science online journal PLOS One. This lent the imprimatur of science to what is in truth a values-based argument for a make-work project on behalf of at least some of the authors, and a shaky argument at that.


Scare tactics
Second, the PLOS One paper was abstracted and globally amplified by mass media under headlines such as “Should cats be culled to stop extinctions?,” the version offered by Helen Briggs of BBC News.
Such headlines framed the paper as generations of cat-hating birders have framed the underlying arguments since the 19th century, as a matter of cats and a handful of other species allegedly jeopardizing biodiversity, mostly of rare birds.
This argument has long been a big fundraiser for organizations such as the American Bird Conservancy. It may be an effective scare tactic among people who have not already taken sides, pro-cat or anti-cat, at a time when the notion that we are in the midst of a so-called “Sixth Extinction” enjoys general currency and is seldom challenged in mass media except by climate change denialists.


(Harvard University photo)
The first premise is wrong
Yet the “Sixth Extinction” hypothesis, popularized by entomologist E.O. Wilson in 1997, was and is wholly based on mathematical modeling, using input data now decades obsolete.
Over the 22 years since then, the numbers of identified species have exponentially increased, the numbers of known extinctions have been dwarfed by the numbers of rediscoveries of species believed to have been extinct, and––despite well-publicized declines of large, charismatic megafauna in the oceans and Southern Hemisphere––net biodiversity has increased on every continent if one counts non-native species.
Which are the majority of species in most habitats.


Self-serving economic arguments
For several generations now, most arguments against doing things to protect endangered species and prevent a supposed “Sixth Extinction” have been based not on refuting the weak arguments that a “Sixth Extinction” is happening in the first place, or considering that the recommended responses may not be effective, but instead on self-serving short-term cost/benefit analyses advanced by various ecologically destructive industries, hellbent on escaping regulation.
The self-serving nature of most of the arguments made against controversial approaches to protecting endangered species, always offered in contexts involving economic interests, superficially seems to lend moral force to arguments for undertaking drastic measures immediately, to prevent the catastrophe presumably looming, even if the drastic measures might accomplish nothing at all.


Concealed self-interest
The purported urgent need to respond to the alleged “extinction crisis” meanwhile obscures the reality that the people and organizations pushing drastic measures also tend to have a significant economic interest as stake. Saving endangered species is in itself a big business, involving billions of dollars and tens of thousands of workers.
Killing island populations of cats, dogs, rats, pigs, goats, and mongooses by any means possible, no matter how ecologically destructive the methods may be, is a drastic measure, employing lots of technicians and scientists, but not really well-considered, even as a means of saving biodiversity in the specific habitat where the killing is done.


New Zealand
A case in point is the ongoing saturation of New Zealand forests with the pesticide Compound 1080, as part of a national putsch against “invasive predators” that is in truth designed to diminish biodiversity by exterminating “non-native” mammals, including brush possums, cats, rats, and rabbits, to benefit “native” birds.
Not all mammals are targeted, however. Livestock and hoofed species favored by hunters are supposedly exempt, regardless of their considerable impact on bird habitat.
But it is not really possible to exterminate one category of animal with mass deployment of a broad-spectrum pesticide without catastrophically harming others.


(Wikipedia)
Killed 98% of non-target deer
An investigation commissioned by the Marlborough branch of the New Zealand Deerstalkers Association on March 21, 2019 extracted from the New Zealand Department of Conservation an admission that an October 2017 deployment of Compound 1080 over a highland farm called Molesworth Station killed 97% of the non-target deer there, perhaps as many as 4,000.
Undeterred, the New Zealand Department of Conservation authorized a scheme to kill 300 feral Himalayan tahr, an endangered species in their native habitat, to feed to kea, a native carrion-eating parrot, while keas’ usual prey is depleted in the wake of Compound 1080 drops in the hills behind Whataroa.
Ironically, kea became scarce in the first place because farmers persecuted them as seasonal lamb predators, and the New Zealand government even paid bounties on them.


Focal points of paper can backfire
Fourteen people are listed as co-authors of “Globally important islands where eradicating invasive mammals will benefit highly threatened vertebrates.”
Altogether, “Fifty authors representing more than forty institutions from around the world contributed to publishing this paper,” according to Island Conservation publicist Sally Esposito.
The paper is long, as PLOS One papers go, at 6,194 words, but if 14 people were genuinely co-authors, their average contribution was about half a page; if 50 people contributed, their average contribution might have been just a paragraph.
Among all this claimed input, none of the participants seem to have realized that their focal points could be turned around and cited as arguments for not funding their intended extermination campaign, even if their input data is accepted without dispute.


75% of extinctions have occurred on islands
Most of “Globally important islands where eradicating invasive mammals will benefit highly threatened vertebrates” is unfortunately written with the quotable fluency of gravel rattling out of a dump truck. Publicist Esposito, however, in her media statement did a reasonably good job of translating the noise into English.
Compiling the paper was led, Esposito said, “by conservation biologists from Island Conservation, the Coastal & Conservation Action Laboratory at the University of California at Santa Cruz, BirdLife International, and the International Union for the Conservation of Nature Species Survival Commission Invasive Species Specialist Group.
“There are approximately 465,000 islands in the world,” Esposito summarized in bullet point, “yet they comprise just 5.3% of the Earth’s terrestrial area. Islands have hosted 75% of known bird, mammal, amphibian and reptile extinctions since 1500.


Critical refuges?
“Islands provide critical refuges for highly-threatened species,” Esposito continued, “currently supporting 36% of bird, mammal, amphibian and reptile species that are classified as Critically Endangered on the IUCN Red List.”
Not acknowledged is that many and perhaps most of these species occupy habitat so limited that they were probably critically endangered from the beginning of their existence.
“Many islands’ species are threatened as a direct consequence of invasive alien species,” Esposito paraphrased. “Cats and rats are the most damaging invasive species known on islands,” a comment taking surprisingly little notice of human activity.


Average success rate of 85%?
The paper, “Globally important islands where eradicating invasive mammals will benefit highly threatened vertebrates,” contends, Esposito said, that “Eradication of invasive mammals from islands is a proven conservation tool”; “more than 1,200 invasive mammal eradications have been attempted on islands worldwide, with an average success rate of 85%”; and that “Larger more remote and technically challenging islands are being successfully cleared of invasive species populations each year.”
All of this is contradicted by other scientific literature favoring eradication of “invasive species,” especially cats and rats.
For example, “A Review of Feral Cat Eradication on Islands,” by eight co-authors, published in 2004 in the journal Conservation Biology, lamented that while feral cats had been extirpated from 48 islands in 30 years of effort, “cats have been successfully removed from only 10 islands larger than 10 square kilometers in size,” representing a 21% success rate.
To be sure, though, the efficiency of cat purges may have improved over the past 15 years.


(Mouse Free Marion photo)
Exterminating four species to maybe save five, for a while
“Globally important islands where eradicating invasive mammals will benefit highly threatened vertebrates,” added Esposito, “highlighted restoration opportunities including Floreana Island, Galápagos Archipelago, Ecuador; Gough Island, Tristan da Cunha Archipelago, United Kingdom Overseas Territories; and Alejandro Selkirk Island, Juan Fernandez Archipelago, Chile.”
According to the paper, extirpating cats, rats, mice, and goats from these three islands “would remove the threat of non-native predation” allegedly threatening two species of petrel, one endangered species of albatross, one critically endangered bunting, and one critically endangered songbird.
On Floreana Island, eradicating cats and rats “will also allow for the reintroduction of 13 locally extinct species.”


How 292 islands were narrowed to 107
How was this determined?
Asserts the paper itself, “Based on extinction risk, irreplaceability, severity of impact from invasive species, and technical feasibility of eradication, we identified and ranked 292 of the most important islands where eradicating invasive mammals would benefit highly threatened vertebrates.
“When socio-political feasibility was considered, we identified 169 of these islands where eradication planning or operation could be initiated by 2020 or 2030 and would improve the survival prospects of 9.4% of the Earth’s most highly threatened terrestrial insular vertebrates (111 of 1,184 species).
“Of these, 107 islands in 34 countries and territories could have eradication projects initiated by 2020. Concentrating efforts to eradicate invasive mammals on these 107 islands would benefit 151 populations of 80 highly threatened vertebrates and make a major contribution towards achieving global conservation targets adopted by the world’s nations.”


Predation is usually not the first or greatest threat
Those are bold but largely unsupported claims. “Globally important islands where eradicating invasive mammals will benefit highly threatened vertebrates” says practically nothing about the many threats to the species at risk from sources other than predation.
And predation is often not the main factor, if even a factor, in driving those species to endangerment.
In all likelihood, factors such as climate change, diminished gene pools, loss of food sources, and disease have already condemned most of the critically endangered species to extinction, regardless of any and all heroic last-ditch measures that might be undertaken on their behalf.


(Beth Clifton collage)
Consider the Bramble Cay melomys
For example, wrote Countdown to Extinction editor John R. Platt on March 21, 2019, beneath the headline “Climate Change Claims Its First Mammal Extinction,” a tiny rodent called the Bramble Cay melomys, last seen in 2009, “lived in just a single habitat, a small reef island at the northern tip of the Great Barrier Reef, near Papua New Guinea. The sandy cay—which only measures about 1,100 feet by 500 feet and rises just three feet above sea level—has in recent years been buffeted by storm surges from extreme weather events. The heavy waters have reportedly wiped out about 97% of the land mass’s vegetation—the melomys’s only source of food.”
Killing such vulnerable species’ predators might buy some of them a little more time, but they are nonetheless barely hanging on, in habitat that has substantially changed from the conditions in which they evolved.


Killing cats, rats, or goats will not bring back a lost marine food web
Because of global warming, for instance, oceanic currents have shifted; more acidic waters are inhibiting the ability of crustaceans and shellfish to build shells, but jellyfish are more abundant than they have been in millions of years; and different plants are favored on the islands in question. These three factors alone have permanently altered the food webs upon which many critically endangered species depend.
No amount of killing “invasive predators” is going to bring back a lost marine food web.
Not only are remnant species doomed by habitat change, but reintroducing species to habitat that no longer suits their needs is foredoomed to failure as well, at significant cost meanwhile in animal suffering.
Meanwhile, extirpating species who are thriving in the altered habitat in hopes of recovering others who are not, and likely never will again, is a cruel exercise in futility.


But suppose the paper’s authors are right?
But, for the sake of argument, let us suppose that the authors of “Globally important islands where eradicating invasive mammals will benefit highly threatened vertebrates” are entirely correct in their assessment of how much they could accomplish to preserve vanishing species if funded to kill “invasive predators” to their hearts’ content.
What would this mean, relative to the greater picture of species and habitat conservation?
The most hostile opponents of endangered species protection, for example in the energy industry, might welcome the news, and even donate toward killing cats, rats, dogs, pigs, goats, mice, and mongooses, because the purported 9.4% of the world’s most endangered species that the killing might save are not the species interfering with oil drilling, building pipelines, clearing rainforests to plant palm oil plantations, shipping crude oil through treacherous waters, and operating nuclear reactors.


(Beth Clifton collage)
Endangered species not all equal in ecological importance
Saving that 9.4% of endangered species, however, might make an impressive “offset”––on paper––for the loss of perhaps 5% of endangered species as result of reckless mainland and offshore energy development schemes.
Consider, though, that the 9.4% of endangered species on the “globally important islands” are all very few in number, of limited range, make little contribution to the survival of other species, and are of miniscule biomass and biological needs compared to the great whales, grizzly bears, sage grouse, orangutans, and myriad other species put at risk by energy development.
All endangered species are not equal in ecological importance. Saving the 9.4% spotlighted by “Globally important islands where eradicating invasive mammals will benefit highly threatened vertebrates” could not begin to compensate for the losses to mainland and offshore ecosystems if such trade-offs benefiting industry and economic development were to be made.


Wildlife overpasses
Even excluding the possibility of cynical trade-offs, however, the resources available for species and habitat conservation are limited. Every cent spent to save the 9.4% of endangered species on remote islands from cats, rats, dogs, pigs, goats, mice, and mongooses is a cent not spent to save the other 90.6% of endangered species.
Many of the other 90.6% have a much better prognosis for longterm survival if their critical habitat is protected by relatively simple, inexpensive, and less ecologically risky measures––including just not doing things that destroy the habitat.
Dollar for dollar spent, building wildlife overpasses and purchasing land to enable species including grizzly bears, bison, elk, bighorn sheep, and pronghorn to migrate safely throughout the Rocky Mountains region, to cite just one example, probably has more potential to benefit more species at risk––including all the many small species whose existence depends on the activity of the large, charismatic megafauna––than anything that can be done for island species whose entire habitat is at imminent risk.


Descended from Edward Howe Forbush
In gist, despite having been published with the trappings of science, “Globally important islands where eradicating invasive mammals will benefit highly threatened vertebrates” is just the latest of a long series of screeds descended philosophically from the 1916 Edward Howe Forbush tract The Domestic Cat: Bird Killer, Mouser & Destroyer of Wild Life; Means of Utilizing and Controlling It.
Forbush (1858-1929) was a late 19th and early 20th century Massachusetts state ornithologist, whose enduring influence has been huge, but whose inveterate hatred of cats was based largely on his own scientific ineptitude.


Blamed cats for gull predation
Among other conspicuous errors, Forbush wrongly blamed cats who were never there in the first place for the decline of roseate terns on Muskeget Island, off Nantucket. The predation that Forbush misattributed to cats was later established to have been caused by gull predation.
Forbush also conflated the Quebecois slang term for raccoons, chat sauvage, and descriptions of raccoon behavior, with second hand anecdotal accounts of cat behavior, and conflated bobcats with domestic cats.
Much that Forbush recommended was attempted, in the name of saving rare birds, including killing thousands of cats, but the recovery of most of those bird species, including roseate terns, awaited much better science, conducted generations later with much less hyperbole.
(See How a birder’s mistakes incited 100 years of cat hatred.)


Paper inadvertently suggests that maybe cats et al are not really a big problem after all
In one sense, though, “Globally important islands where eradicating invasive mammals will benefit highly threatened vertebrates” represents a retreat from Forbush, if perhaps an unwitting retreat.
While ailurophobes from Forbush to the present national policymakers in Australia and New Zealand have argued that cats menace birds and other wildlife anywhere and everywhere, the authors of “Globally important islands…” expand the purported threat to include dogs, rats, goats, pigs, mice, and mongooses, yet narrow the scene of the alleged crimes to much less than 1% of terrestrial habitat.


(Anthony Marr photo)
This suggests some recognition that these so-called “invasive” species are much less a threat to biodiversity than has been widely advertised, and are perhaps not really any threat at all.
As a person living in the US for many years, out in the country on farm land and observing the depredation of feral and free roaming cats, I cannot understand how anyone with any scientific OR common sense cannot see the extreme threat from these outdoor cats. Now, I am not speaking as a person who hates cats. I have cats and have for many years…indoor cats. Because when cats are outdoors, they kill every bird they can, even when they do not eat it. They stalk and kill hummingbirds at flowers, they kill many native baby birds who normally leave their nests a week or more before they are able to fly. During this time they are crawling around in bushes where they are easily taken by cats. Then there are the baby bunnies, and the small herps, all of which are killed by cats. With cats, rats, and mongooses on islands, well we already know that is a recipe for extinction because we have the history of it. And to suggest that there are other reasons that birds and animals are disappearing, such as climate change, well, that is all the more reason to remove cats and other non-natives to reduce the pressure on the native populations.
The above comment conflates the activities of owned, fed cats who are allowed to roam outdoors with the very different habits of feral cats who hunt for a living, and in remote island habitats have not been fed by any humans, or by human activity, in often hundreds of years. Owned, fed cats are basically subsidized sport hunters. They can afford to hunt birds and sometimes lizards by day, even though these are very inefficient pursuits for a cat in terms of energy expended relative to nutrition gained, because they always have full dishes at home––and since cats sleep more than 70% of the time, even the most active diurnal hunters will tend to spend their nights home on a bed. Feral cats, having to hunt for a living, do their sleeping by day and concentrate their hunting hours into the night, when few birds and lizards are about, but small rodents are most active and accessible. On small islands without rodents, feral cats may hunt birds, of necessity, but this brings up another of the basic ecological principles of predation: predators tend to become malnourished, fail to reproduce successfully, and die out long before prey species. Only if something else drastically and abruptly reduces prey abundance is any predator capable of killing the last of a prey species, after which the predator will starve to death. Taking this into account, the common birder claim that cats, rats, and mongooses have caused bird extinctions on various islands is essentially nonsense. In Hawaii, for example, cats, rats, and mongooses have long been blamed for species losses caused mainly by conversions of habitat to human purpose, mostly agricultural; pesticide applications to aid crops; harbor construction; and every now and then, a volcanic eruption.
Of further note, and ecological importance, is the difference between “additive” and “compensatory” predation. “Additive” predation adds mortality to the mortality a species is already experiencing. Pesticide applications, for example, are mostly additive, because they indiscriminately kill insects and other animals, such as birds, who would otherwise live to reproduce. Cats killing baby birds who jump or are pushed by siblings out of nests before they can fly are exercising compensatory predation, meaning that those birds are highly unlikely to survive under any circumstance. In absence of cats, if other predators such as foxes, dogs, coyotes, and predatory birds such as crows and gulls do not kill the fallen fledglings, fire ants, cars, and lawn mowers will, among other threats.
Finally of relevance, compensatory predation, including by cats, is a major brake on the spread of “feeder diseases” among birds. For example, the post-1994 spread of Mycoplasma gallisepticum among fed bird species, when plotted on a map, appears to be among the largely unrecognized side effects of the introduction of neuter/return feral cat control in the early 1990s, combined with the explosive rise of backyard bird-feeding during the same time frame. As feral cat populations plummeted, shown in animal control intake data at a time when making vigorous efforts to trap and kill feral cats remained standard operating procedure, Mycoplasma gallisepticum outbreaks followed, right around the U.S., because other predators had not yet taken over the job of killing diseased birds before they could infect others.
The greatest threat to wildlife has and continues to be humans. I have read numerous research that states the greatest threat to wild bird population is the destruction of their habitat especially with migratory birds that may have no habitat to return to. Humans really have their heads in the sand when they think eradicating other species is going to prevent extinction. One has only to look at the orangutan population whose habitat is being destroyed by production of palm oil and may bring about their extinction in the wild in the next few decades. Same is true for wildlife in Africa and many primates as habitat is destroyed for oil production, mining, lumber, poisoning of scavenger birds, and now the prospect of palm oil production. The statistics for the past fifty years speak for themselves regarding the dramatic decline of indigenous populations, much of it also due to poaching. The effects of climate change are already present and the catastrophic effect it already seems to be having on many species including humans.
I have been able to effectively reduce the feral cat population in my neighborhood through neutering and spaying, often using my own funds, or the help of TNR programs, while my neighbors turn a blind eye. So, where is the concern by the majority of humans for destruction of species by cats. The simple answer is that it mostly doesn’t exist and most humans do not take responsibility for it or even care about it. Our local TNR programs, run mostly by volunteers, are overwhelmed. It is also false that cats will kill just about any bird they can. I have five cats and only two actually will catch birds and rodents, the others could care less as long as they are fed. In my 66 years I have never seen a cat ever catch a hummingbird. Where I grew up, we had outdoor cats and lots of hummingbirds. They would watch the hummingbirds but never once was one caught. None of my cats has ever been able to catch and kill a blue jay or cardinal. The few times they have caught one it fights back with very a strong beak and the cat gives up. If they catch a bird it is usually a smaller bird like a sparrow or starling. I might add we have an overpopulation of starlings as well as pigeons, so cats are not doing that much harm there. My city actually has nesting boxes for falcons to curb the pigeon population. However, the weight of pigeons is often even too much for the falcons and I have witnessed them more than once swoop down to a bird feeder to catch a smaller and easier prey. This also leads to another topic. In my opinion bird feeders are not necessarily a benefit to birds, as predators will use them as hunting grounds.
For a feral cat (and I have rescued several), hunting requires energy especially in a difficult environment and when disease and illness are ever present. Of all the feral cats I have actually provided food for, I have never seen one once with any type of prey. What happens is they come to my house where there is guaranteed food, water, and shelter. One would actually come to my back cat door each day for a big bowl of moist cat food and lactose free milk. He would even trudge through deep snow each day. His goal was not in trying to expend a great deal of energy to hunt, which may prove unsuccessful, but to come to the guaranteed source of food that would be worth his expenditure and conservation of energy. He continued to do this for two years until he became ill and I brought him inside where he lived the last six months of his life in comfort.
Cats have always had a beneficial effect and been used by humans to protect things like grain storage. Barn cats were essential, but they were also essential to the home, and I can testify to that having had a rodent-free home in the 36 years I have lived here. But cats are often considered disposable animals and the 19 I have rescued in 36 years did not come from nowhere. They were not lost, they were abandoned, and they came to where the food requiring the least expenditure of energy versus hunting was, and a greater chance for their survival.
The problem has never been and will never be other species. The problem is the irresponsibility of humans and ignoring the impact they have had on the Earth and other species which in turn can impact other species. A dangerous double effect.
What was it that Einstein is purported to have said about repeating the same action and expecting different results?
One thing that never seems to change despite claims that humans are getting smarter is human stupidity. Using any means necessary to justify a desired action is also an indicator of sociopathy, but in the present “just us” system, these self-servers run wild, killing the innocent and vulnerable and leaving those of us who care about them powerless, it seems, to stop the criminals and their crimes.
Hear, hear!!
Outstanding article……you guys do great research and grasp things right-on with all your articles. Good minds. Some of this article also applies to USA’s wildlife, large & small predators and the governments/hunters controversial killing management by numbers. Of course I am a biased cat guy and against the wildlife and domestic animal abuse going on around the world, both legal and illegal!
Hear, hear!
The only real invasive species is people. The human population explosion is trashing every ecosystem on the planet.. We need a huge increase in worldwide human birth control.
Amen!
Thanks for shining much-needed light on this subject!
Hoping everyone reading will share the article and do something every day to educate the world about this issue, because MANY innocent cats’ lives are at stake. Everyone with a device of any kind is capable of sharing. PLEASE do so.
We work for heiping cats in Amami Oshima Island, Japan, where a rare species, Amami rabbits live. —Yoshihiro Yamazaki, Professor, Fukuoka University, Japan.