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Edited by Karl Weber

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What does an unusually large, ugly, invasive species of toad have to do with global warming, international trade, and the survival of biodiversity? Quite a lot, actually. Mark Lewis’s amazing and hilarious documentary Cane Toads tells the story of Bufo marinus, which was introduced to Australia in 1935 to control bugs but which quickly became a far greater menace than the beetles they eat. Today they number in the hundreds of millions and are taking over Australian habitats at 25 miles per year, spreading disease and killing native species as they go.

Rogue Species explains the little-understood dangers of invasive species. Ranging from the zebra mussel (currently threatening the health of the Great Lakes) to the infamous kudzu vine (a Japanese import that now smothers seven million acres in the American southeast), these disastrous human blunders threaten the biodiversity on which all life — including our own — depends. The book will raise readers’ awareness about the threat of non-native species, increase their appreciation of natural biodiversity, and explain what they can do to help protect unique ecosystems wherever they live or travel.

PREFACE

There really is nothing quite like a Mark Lewis movie. I suppose if one had to describe it in a single phrase, one would have to call it a "nature documentary," but even to utter those words is to realize how hopelessly inadequate they are at suggesting the odd, lovable blend of deadpan comedy, gentle social satire, and subtly parodic genre play that characterizes a film like Lewis's legendary Cane Toads.

Yet at the same time, Lewis's work has much of the appeal—and sheer educational impact—of the traditional nature movie. When you watch Cane Toads, or its 2010 sequel Cane Toads: The Conquest, you do in fact learn an awful lot about one of the world's most unusual, tenacious, repulsive, yet somehow endearing creatures and its remarkable, and remarkably complex, relationship with the Australian people who have become its unwilling hosts and, some would say, victims. Practically every scene will have you gasping "I didn't know that!" even as you are marveling at the technical cleverness of Lewis's film-making technique and the sly humor that infuses it all.

I could go on trying to describe the experience of watching a Mark Lewis picture, but I think I will stop here and simply insist that, if you haven't already had the pleasure of watching Cane Toads, you remedy that failure as quickly as possible. Until you do, you can't imagine what you have been missing.

And as you watch the believe-it-or-not story of the cane toad's slow conquest of northern Australia (and the multifarious, often hilarious reactions of the millions of Aussies it encounters), you will gradually come to recognize that this is also a movie about one of the most serious environmental issues of our time—the problem of invasive species and their impact on biological diversity.

In a vague way, we all know that, over the past hundreds and thousands of years, plant and animal species have migrated and spread from their ancestral origins into new habitats elsewhere on the planet. We learn in school about how the Europeans brought the horse to the New World, and perhaps we've picked up some scraps of knowledge about how our favorite foodstuffs have roamed the Earth, often becoming staples in countries quite distant from where they originated (as the potato did in Ireland, or the tomato in Italy). These kinds of transplantations seem colorful and quite benign.

But there's a far more complex, and troubling, side to the story of species migration—one that the tale of the cane toad embodies and that the book in your hand explores in depth. It's a story of human interference with nature—usually well-intentioned but often ignorant, heavy-handed, inadvertent, and blundering, producing unexpected consequences and increasingly threatening the amazing heterogeneity of environments that makes our world so endlessly beautiful and fascinating.

It's about diseases of plants, animals, and humans being carelessly spread from one continent to another by travelers and traders, wreaking havoc among populations that evolution hasn't prepared to cope with them.

It's about pests like the Asian long-horned beetle and the zebra mussel taking over entire ecosystems, ravaging native species, and causing billions of dollars of economic loss.

It's about species like the Burmese python establishing a foot-hold in environments, such as Florida, that have never known their kind, and threatening destruction to unique endangered competitors for resources like the alligator and panther.

It's about exotic pets being abandoned in foreign habitats, or "set free" by well-meaning but misguided owners, only to end up suffering needless deaths or—perhaps worse—causing the deaths of countless other creatures.

And if allowed to play out to its logical conclusion, species migration may lead to the ecological disaster of a world transformed into what nature writer David Quammen eloquently describes as a "planet of weeds"—a single ecosystem dominated by a handful of ultra-hardy species, in which the wonderful, mind-boggling diversity of the Earth's historic habitats is lost forever.

Biological invasions by creatures traveling from one environment into another are nothing new, of course. There are few impassable boundaries in the natural world; even great mountain ranges, vast deserts, and trackless oceans can be, and have been, crossed by handfuls of adventurous plants and animals—and it takes only a handful to create a colony from which, in time, a population of millions may spring.

But in the modern era—an era of global trade and tourism, and of the increasing homogenization of environments by economic and political forces—the pace at which the planet's inherited species are intermingling has accelerated dramatically, with results no one can predict.

There's no simple solution to this problem. It wouldn't be possible to divide the world into self-contained quarantine zones even if we wanted to try. But in the coming decades, unless the people of the world—themselves the ultimate "invasive species"—learn to take more seriously the implications of their global wanderlust and its biological impacts, we and our children will suffer the unforeseeable results.

The purpose of this book is to serve as a guide to the important, intriguing, and disturbing issue of rogue species. Authored by many of the world's leading experts on invasive species, it has been designed for the lay reader, with the goal of making the entire phenomenon—its causes and consequences—as vivid and understandable as possible. In its pages, you'll discover the stories of many of the world's most amazing creatures—and you'll also learn some of the specific steps we can take, both as individuals and as the collective stewards of Planet Earth, to help protect the global diversity and beauty of nature that we all cherish.

In the end, the journey that begins with Cane Toads will take you around the world—and finally back to your own home town, which is where the task of preserving the planet and all the marvelous creatures in it must begin.

Karl Weber
Irvington, New York

PART I

THE CANE TOAD SAGA

The Toad's Tale

A True Fable of Science and Society

NIGEL D. TURVEY

What drives otherwise pleasant and reasonable people to create environmental havoc? Who were the farmers, politicians, and professional scientists who released such a toxic pest as the cane toad into Australia? Were they alone? What were they thinking? Why did it seem such a good idea at the time?

At the core of these questions is the need to understand such people in their own habitats and their own eras; to understand the influences on them, their backgrounds, their upbringing; to understand their hopes and fears, their thoughts. These were trusted pillars of the community who allowed a few cane toads to be released into an unsuspecting environment. Their ordinary actions had extraordinary impacts.

Such questions drive Nigel Turvey's research and his writings on environmental issues—a unique combination of history and science.

Nigel has roamed the landscapes of Australia and Asia since graduating as an environmental scientist more than thirty-five years ago. As an educator, scientist, and businessman, he worked in the forests of Australia and the rainforests and grasslands of Southeast Asia. He is now working with forest communities, governments, and the timber industry to protect remaining rainforest habitats in Indonesia.

Nigel and his wife, Monica, currently live in the Northern Territory, Australia. Cane toads have just recently arrived there after spending seventy-five years hopping across the top of northern Australia.

In "The Toad's Tale," Turvey explains the amazing history behind the saga of the cane toad—a tale of human folly, hubris, and good intentions gone wrong that offers lessons for all of us.

Seventy-four years after their release in north Queensland, cane toads have covered more than 2,400 kilometers across tropical Australia; the "toad slick" has now reached the far west of the continent.

How did this remarkable expansion happen? Who were the people who triggered it? What could they have been thinking? I wanted to understand more about these people and the times they lived in, and I got lucky. The archive staff in BSES Limited—the successor to the Queensland government's Bureau of Sugar Experiment Stations (BSES), now owned by Australian sugar cane growers and millers—discovered some ancient and rusted files that had survived the Brisbane floods of 1974. Thanks to diligent public service record keeping, and the permission of BSES, I found the chain of events I was looking for.

Water-stained documents in faded musty manila folders revealed the story behind the release of cane toads in Queensland in 1935. It is a tale of biological control gone wrong. But what further emerged was that their release was endorsed by leading international and Australian scientists, stridently supported by the sugar industry, promoted by the premier of Queensland, and even supported by the prime minister of Australia. In short, many prominent people thought that the introduction of cane toads into Queensland's sugar cane fields was a good idea.

For almost three hundred years, the cane toad's tale has been written in the margins of colonial expansion and the sugar trade. In 1735 Carolus Linnaeus, the father of the systematic classification used universally by scientists, met a wealthy collector of natural curiosities, Albertus Seba, who had in his collection in Amsterdam a giant toad purchased from a sailor who brought it from Suriname; it was a by-product of the Dutch trade in slaves, sugar, coffee, and the booty of piracy. Linnaeus included it in his Systema Naturae as Rana marina; it was later reclassified Bufo marinus— the marine toad. But Linnaeus did not have much regard for toads and their ilk; he reasoned that their "horrible cold bodies, filthy colour . . . fierce faces, ponderous features . . . raucous calls, squalid habitats, and dreadful venom" accounted for why "the Creator had not made many of them."¹

But the toad—variously called aguaquaquan, sapo grande, marine toad, giant American toad, great Mexican toad, South American toad, Central American toad, Suriname toad, Queensland toad, and, eventually, cane toad—did serve a practical purpose. In the early nineteenth century, the toad was taken from its home in Central and South America to the sugar plantations of the Caribbean to catch insect pests, and rats as well,² because it eats whatever comes within range, thus applying an inbuilt logic: If it's big, avoid it; if it's small, eat it; if it's in between, mate with it—scarper, scoff, or screw.

Pest problems in Queensland's new cane fields in the late nineteenth century were much like those in the Caribbean sugar plantations: White grubs, the larvae of local species of greyback canegrubs (sometimes called witchetty grubs), were attacking the roots of sugar cane in preference to tough old native grasses. And the Caribbean experience was so widely known that when Albert Koebele—a disciple of Charles Valentine Riley, the father of biological control—visited Australia in 1888, he declared, "Without doubt the presence of toads . . . would have a remarkable effect in diminishing the number of these [greyback canegrubs] as well as many other injurious insects."³ But no one followed his advice at the time.

In 1898, after a brief war with Spain, the United States flexed its newfound colonial muscles to take control of Cuba, Puerto Rico, the Philippines, and Guam and annexed Hawaii in the same year. Louisiana's sugar planters were handed a wealth of new territories—and the pests to go with them. Sugar linked America's new lands with Australia; James Chataway, a Mackay sugar planter, was the Queensland correspondent for the newspaper The Louisiana Planter and Sugar Manufacturer and, later, as minister for Agriculture and Stock, he brought Walter Maxwell from Hawaii, formerly of Louisiana, to evaluate the state of the sugar industry of Queensland.⁴ In December 1900 the Bureau of Sugar Experiment Stations was established under the Queensland Department of Agriculture and Stock, with Walter Maxwell as director employing a succession of American scientists, as well as locals, to solve the sugar industry's problems.

The U.S. Department of Agriculture trained staff to deal with the troubles of emerging agriculture in the new lands. White grubs became so widespread in Puerto Rico that in the early 1920s the Agriculture Experiment Stations on the island imported cane toads from Jamaica and Barbados.⁵ Within ten years of their introduction, toads were everywhere and white grubs had all but vanished.⁶ But was this entirely the work of the toads? Raquel Dexter, teaching in the biology department of the University of Puerto Rico, devised an experiment to prove a link between the abundance of cane toads and the decline in populations of white grubs. She cut open the stomachs of 301 toads and found that 51 percent of the insects in the toads' stomachs were "injurious to agriculture," 42 percent were "neutral species," and 7 percent were "beneficial" insects.⁷ Here was the proof!

In 1932 the members of the International Society of Sugar Cane Technologists gathered for their Fourth Congress in San Juan, Puerto Rico, where Dexter praised the "amphibian immigrant which is doing its full share of benefit to our sugar industry and to which this International Congress should pay a tribute of gratitude."⁸

Queenslander and plant pathologist Arthur Bell represented BSES at the Congress, but he did not hear Dexter's talk because he was busy delivering his own paper in a concurrent session— the curse of conferences even then. But Cyril Pemberton, entomologist for the Hawaiian Sugar Planters' Association, chaired Dexter's session. Pemberton was so taken with the "proof "she presented that he purchased two suitcases and stuffed them with wood shavings and 152 toads before he sailed for New York, then took a train to San Francisco and a steamer across the Pacific to release the toads in their new home in Hawaii (149 had survived).⁹

This was the Great Leap Forward for the cane toad. The 1932 voyage of two suitcases full of toads from the Caribbean Sea to the middle of the Pacific Ocean was the greatest geographical leap that Bufo marinus had made, and survived to breed, in 40 million years. And thanks to Cyril Pemberton's enthusiasm, Hawaii became the epicenter of the toad's radiation into the islands of the Pacific.

This is where Australia's problems began—with the myth of scientific proof. Raquel Dexter's experiment revealed only what the toads had eaten for their last meals and what their organs were slow to digest; it proved nothing at all about the dynamics of populations of toads and white grubs. She should have asked whether the toads' ability to eat anything that wandered close had any effect on populations of female beetles, or on the overall number of eggs laid, or on the number of beetle eggs turning into white grubs in cane fields. And what impact did changes in climate, varieties of cane, cultivation techniques, irrigation, and the use of fertilizers have on populations of white grub in cane fields in the decade since the introduction of the toad? All of these questions went unasked, and unanswered.

But the real conundrum is that Pemberton, a senior scientist in a respected institution, accepted Dexter's conclusions as proof and with such gusto that he populated Pacific islands with toads. In Puerto Rico today, according to Dr. David Jenkins, entomologist in the USDA Mayaguez Research Station, white grubs are back as a pest and the toads are as abundant as ever.¹⁰

Interest in the toad in Australia was slow to build. In a letter written in September 1933 to his staff at Meringa in north Queensland, Arthur Bell asked whether they thought the toad would help control greyback canegrubs. Reg Mungomery, assistant entomologist, replied to his boss that he did not think toads would be much use because adult female beetles were vulnerable for less than an hour after emerging from the soil before they flew to trees to feed, and the common green frog was already known to eat them with little overall impact on populations.¹¹ There was no hurrah for the toad at Meringa.

The giant toad was ugly, but in 1933 so was the control of white grubs: soil fumigating with carbon bisulphide or paradichlorobenzene, drilling of white arsenic (arsenic trioxide) into the soil, or dusting with Paris Green (copper acetoarsenate).¹² By contrast, biological control was much less unpleasant and was in vogue in Queensland in the 1930s because Australian ladybird beetles—called vedalia beetles—had successfully been used to control cottony cushion scale infestations in the Californian citrus industry.¹³ Queensland scientists had also introduced the moth Cactoblastis cactorum from Argentina to control another introduced pest, the prickly-pear cactus. Methods of eradicating prickly pear were vile and ineffective, including arsenic pentoxide, sulphuric acid, and arsenous chloride sprayed by men on horseback. ¹⁴ The Commonwealth Prickly Pear Board had tried around 150 different species of insects to control the cactus pest with little success until larvae of the moth proved effective. By 1928, the moth had eradicated the cactus in Queensland, and Reg Mungomery was on the team that made it happen.

The Cactoblastis moth was as spectacularly successful in Queensland as the vedalia beetle was in California, and these well-publicized successes set the scene for the acceptance of biological control in agriculture around the world.

The 1934 season was a good one for greyback canegrubs in Queensland—a bad one for cane growers—and BSES was expected to solve the problem.¹⁵ By the start of 1935, Reg Mungomery had completely changed his mind about the toad. Having read Raquel Dexter's paper and reports of the toad in the West Indies, he wrote to Arthur Bell to say that he now thought the toad would be beneficial in terms of eating not only adult beetles but also weevils, borers, caterpillars, and rats.¹⁶ William Kerr, director of BSES, began arrangements to send Reg Mungomery to Hawaii to collect a colony of giant toads.

In March 1935, Dr. John Cumpston, the Commonwealth director-general of Health, approved the toads' importation.¹⁷ It was an unremarkable event. At the time, the Commonwealth's Quarantine Act, rather than being concerned with importation of pests, was designed to prevent epidemics of influenza and plague in humans and to control the importation of diseased plants and animals.¹⁸

Mungomery sailed for Hawaii in April 1935 and returned to Sydney on the Matson Line's Mariposa in the middle of June 1935, travelling cabin class—the equivalent of business-class travel today—with 102 toads. After breeding them in Meringa, he released 2,400 toads into the Little Mulgrave River and at other sites around Gordonvale in northern Queensland on August 19, 1935.¹⁹ It was just one week before the start of the Fifth Congress of the International Society of Sugar Cane Technologists, hosted in Brisbane by BSES—the successor to the Puerto Rico Congress of three years earlier.

At the Congress, the chief advocate of the toad—Cyril Pemberton from Hawaii—was on hand when Mungomery reported the successful captive breeding of the toad and its release. Congress delegates later viewed the toads at Meringa, where the Queensland minister for Agriculture and Stock, Frank Bulcock, opened the research station.²⁰ But after the Congress on November 8, 1935, William Kerr, director of BSES, received a bombshell—a telegram from Dr. Cumpston of the Commonwealth Department of Health that prohibited further releases of the toad. The post-Congress euphoria evaporated.

The BSES files reveal the chain of events that led to the ban and the flurry of activity that followed. At the close of the Congress, Pemberton had gone to Sydney to board his ship home to Hawaii, and with some time to spare he had caught up with a colleague, Walter Froggatt, a retired New South Wales government entomologist and then president of the Naturalists' Society of New South Wales. Froggatt was dismayed over Pemberton's news of the introduction of the toad to Queensland and immediately lobbied the Commonwealth government to ban further releases of toads. He warned that "[t]his giant toad, immune from enemies, omnivorous in its habits, and breeding all year round, may become as great a pest as the rabbit or cactus."²¹

Sir David Rivett, chief executive officer of the Council for Scientific and Industrial Research (CSIR)—the forerunner of CSIRO—was brought into the debate, but he supported BSES, saying, "I am very glad to know that Mr C. E. Pemberton is prepared to defend the wisdom of the importation despite the decidedly pessimistic forecast of the New South Wales entomologist."²² But his support was self-serving, because CSIR was working on the release of the European toad, Bufo vulgaris, to control pests in pastures. There was additional support for the toad from Robert Veitch, the chief entomologist of Queensland, as well as representation in person from Arthur Bell in Canberra, but Dr. Cumpston was unmoved.²³

It was time for the sugar industry to flex its considerable electoral muscles. The director of BSES, William Kerr, wrote to the Australian Sugar Producers' Association and the Queensland Cane Growers' Council announcing the ban. The Council's secretary, Bill Doherty, immediately telegraphed his members asking for "strong agitation against Federal authorities."²⁴ Kerr also briefed his minister, Frank Bulcock, who in turn sent a glowing recommendation of the toad to the premier of Queensland, William Forgan Smith, suggesting he make representations to the prime minister.²⁵ Forgan Smith was a former minister for Agriculture and Stock and represented the sugar seat of Mackay; he had championed the sugar industry throughout the Depression and had recently addressed international delegates at the Sugar Technologists' Congress.²⁶

But here the paper trail ended; BSES had no need to see the correspondence between the premier and the prime minister, and I had to track the next letter through the Queensland State Archives. And there it was. On December 2, 1935, Forgan Smith sent the prime minister, Joseph Lyons, an almost verbatim version of Bulcock's letter—a copy of the original letter from William Kerr—requesting that the ban be lifted.²⁷ The very next day, Dr. Cumpston telegraphed the Queensland undersecretary for Agriculture and Stock to partially lift the ban, and the prime minister added later that "no objection would be raised against the release of toads in those areas in which liberations have already been made"—the Cairns, Gordonvale, and Innisfail region.²⁸

Here was the smoking gun; support for the toad went right to the top, and the sugar lobby was strong enough that Joseph Lyons was able to overrule his head of the Department of Health—in an instant.

An unhappy Dr. Cumpston wrote to the Queensland under-secretary to say, "It is recognised, of course, that your Government is prepared to accept its share of responsibility for the action which is now being taken."²⁹ BSES still wanted the ban lifted completely because cane growers were now calling for their allocation of toadlets, but first it had to satisfy a snubbed and unhappy Dr. Cumpston.

Walter Froggatt's criticisms of the toad became public in January 1936, when his article was published in The Australian Naturalist .³⁰ As a former government entomologist, Froggatt had been responsible for knocking on the head other crazy proposals for biological control, including a plan to use red meat-ants from South Africa to destroy baby rabbits in their burrows; a scheme to use ferrets, stoats, weasels, and the mongoose to exterminate rabbits; and an inspired suggestion to import vultures from Texas to control blowflies.³¹ About the toads he wrote: "There is no limit to their westward range, and [they] . . . will probably adapt themselves to our mountain ranges, and even reach the river banks and swamp lands of the interior."³²

There in the BSES files, among the bland carbon copies of official correspondence, is a letter from Walter Froggatt to Arthur Bell, handwritten on the letterhead of the Naturalists' Society of New South Wales and graced with its gum leaf emblem. With a career of experience behind him and summoning as much passion as possible in the two dimensions of the page and the protocol of the medium, Walter Froggatt had written: "No organisation, or even a single state of the Commonwealth has the right to independently introduce such a possible menace to the continent as Bufo marinus."³³

In July 1936, the Queensland undersecretary for Agriculture and Stock collated the BSES defense of the toad for the benefit of Dr. Cumpston. It included a detailed critique of Froggatt's article, a letter from Cyril Pemberton supporting the "beneficial and innocuous creature," a review of literature, and a further character reference for the toad from Hawaii.³⁴ In August 1936, Arthur Bell, perpetuating the charade of science, sent Dr. Cumpston yet another copy of Raquel Dexter's paper and a repeat of her experiment on toads by the staff of BSES (except that, inexplicably, in this case they examined the toads' excreta for evidence of their last meals).³⁵

Two studies of the toads' diet seemed to convince Dr. Cumpston. There was no request for additional ecological studies; he lifted the ban on the wider release of the toad in September 1936.³⁶ But the damage had been done a year earlier when the first toads had been released. With a female toad capable of spawning around thirty thousand eggs at a sitting, there was no hope of getting those tadpoles back in the jar.

The BSES team at Meringa continued to breed and distribute thousands of cane toads around the sugar-growing areas of Queensland for at least another three years.

Reg Mungomery's initial assessment was correct—cane toads did not control white grubs. And Walter Froggatt proved to be a prescient critic—cane toads would reach far beyond the Kakadu wetlands. The toad's subsequent colonization of a 4,000-kilometer band of tropical and subtropical Australia was the greatest mass migration in its globe-trotting history.