Deciphering Amphibian Declines Ashley Mattoon

Chapter 4

In 1973, an Indonesian scientist visiting skin of the frog’s stomach. Soon another Australia discovered a nondescript, muddy- tadpole was found in the aquarium. Then brown frog hidden in the streams of the two more appeared. The researchers finally remote, densely forested mountains of decided to remove the frog and dissect it. southeastern Queensland. The frog attracted As they reached into the aquarium and a great deal of interest, since it was the first grabbed the animal, it flexed backward and aquatic stream frog known to inhabit the opened its mouth wide. As the researchers continent. It was unusual in other ways as described in Science, “eight juvenile frogs well. Michael Tyler, an Australian herpetolo- were then propulsively ejected in groups of gist, noticed that the frogs would occasion- two or three in no more than 2 seconds. ally collect in pools of water in groups of Two further juveniles were ejected after a three or four—forming sort of a ring of few minutes and, 30 seconds after the frog frogs, touching by the tips of their toes.1 had been transferred to preservative, three But the strangest characteristic was dis- more were disgorged similarly.”2 covered in November 1973, when two Scientists found that the frog incubated researchers in Brisbane were cleaning an its eggs in the mother’s stomach—a form of aquarium that held one of the frogs. They parental care that was completely unprece- saw it swim up to the surface of the water dented among vertebrates. That gave the and spit out six live tadpoles. They couldn’t species its common name: the gastric- quite believe what they saw: where could brooding frog. Normally, whatever a frog the tadpoles have come from? Perhaps the swallows would be digested by the stom- species was related to a South American ach’s natural chemicals. But somehow this frog whose fertilized eggs develop in the species was able to turn off its digestive father’s vocal sacs. But they also noticed a enzymes for the six or so weeks it took for peculiar mass of wriggling bodies under the the eggs to develop. This was particularly State of the World 2001 DECIPHERING AMPHIBIAN DECLINES

intriguing as it suggested the frog’s physiol- not been seen since. And in the tropical rain ogy could hold clues to treating people forests of northern Queensland, large-scale with gastric ulcers and other stomach ail- declines began in 1989—seven species ments. But in 1981, as research was getting dipped sharply; four can no longer be found under way, the frog suddenly disappeared in the wild. All these species were locally from the mountain streams where it had endemic: they did not exist anywhere else in once been so abundant. It has not been the world.4 found again since.3 Several hypotheses about Australian amphibian declines have been proposed, By the end of the 1980s, reports of but there are no widely accepted, definitive declines and disappearances emerged answers. And the mystery spreads beyond Australia. By the end of the 1980s, reports from most regions where amphibians of declines and disappearances emerged were reasonably well monitored. from most other regions of the world where amphibians were reasonably well moni- It was just pure luck that scientists hap- tored—in North America, parts of South pened to stumble on the gastric-brooding America, and Europe. In Costa Rica’s frog in the twilight of its existence. Here Monteverde National Park, populations of was a species humans had been living beside 20 of the 50 native amphibian species have for millennia, yet somehow it had escaped declined or disappeared since 1987. And in notice. And this creature had a unique California’s Sierra Nevada, five out of seven adaptation for brooding its young—if we native amphibians have disappeared or had not actually seen it, we would never declined sharply since the early 1900s. (See have thought it possible. The frog had a lot Table 4–1.)5 to teach us, but for some unknown reason, As news of the declines began to surface our time with it was cut short. around the world, scientists wondered if The loss of the gastric-brooding frog they were simply anecdotal accounts that attracted a great deal of attention in the sci- reflected natural population fluctuations. entific community, largely because it was But there were some uncanny similarities— such an unusual creature. But it turns out patterns that suggested something more that its mysteriously sudden disappearance ominous could be taking place. The was not exactly unique to the species. By declines were, in the first place, very rapid. the end of the 1980s, at least 13 other They sometimes involved whole assem- amphibian species had gone into serious blages of species, rather than just one or decline or disappeared entirely from moun- two. And they were occurring not just in tainous regions of eastern Australia. The areas that were obviously disturbed, but in southern dayfrog, which had commonly some of the world’s most carefully protect- been found in the same areas as the gastric- ed parks, such as Costa Rica’s Monteverde brooding frog, has not been seen in the Cloud Forest Reserve and Yosemite wild since 1979. Three other species in National Park in the western United States. southeastern Queensland have declined by These were not the kinds of losses that more than 90 percent. Further north, in the could be readily predicted—or explained. tropical forests near Eungella, two species Something peculiar was happening to declined sharply in 1985; one of them has Amphibia—something bad enough to dis-

64 State of the World 2001 DECIPHERING AMPHIBIAN DECLINES

Table 4–1. Selected Large-Scale Losses of Amphibians

Location Species of Concern Status Possible Cause

Montane areas 14 species of frogs, including Sharp population declines Parasitic fungus, possibly of eastern the southern day frog and since the late 1970s. introduced through inter- Australia the gastric-brooding frog. Four species are thought national trade in aquarium to have become extinct. ﬁsh and amphibians.

Monteverde 20 species of frogs and Disappeared after Climate change, possibly region of toads (40 percent of total simultaneous population combined with other Costa Rica frog and toad fauna), crashes in 1987. Missing factors such as parasites. including the golden toad. throughout 1990–94 surveys.

Las Tablas, Costa More than 15 species. Severe declines since Chytrid fungus infection, Rica, and the early 1990s. possibly combined with Fortuna, other factors. Panama

Yosemite region Five out of the region’s Severe declines—one Overall cause unknown. of California seven frog and toad species has disappeared Introduced predatory species—including the entirely, another has ﬁsh combined with mountain yellow-legged declined to a few small drought-induced loss frog and the foothill populations. of habitat contributed yellow-legged frog. to the decline of some species.

Montane areas 12 of 18 endemic Three may be extinct, Unknown. Possibly of Puerto Rico amphibian species. the others are in climate change. decline or at risk.

Cordillera de Five species. Sharp declines since Unknown. Possibly Mérida, the 1970s. deforestation, ﬂoods, Venezuela roadkill, pollution.

Reserva 8 out of the reserve’s Disappeared or declined Unknown. Possibly Atlântica, 13 native frogs. in the 1980s. unusually dry winters, Brazil pollution, or a combina- tion of both.

SOURCE: See endnote 5. tinguish it from the broader tragedy known While there are still many unanswered ques- as the biodiversity crisis. tions, there is now little doubt that the More than a decade since amphibian problem is real, and that a complex mixture declines ﬁrst emerged as a major scientiﬁc of causes is involved. More important than mystery, there have been significant the many details, however, is the realization advances in our understanding of the issue. that it is not just the loss of frogs and sala-

65 State of the World 2001 DECIPHERING AMPHIBIAN DECLINES manders that should concern us, but what Scientists have thus far identified nearly their loss tells us about the state of the envi- 5,000 species of amphibians—more than ronment. Stemming the loss of amphibians the known number of mammals. And com- will involve changes far beyond the protec- pared with other groups of organisms, new tion of wetlands or forests. It will require species of amphibians are being described at fundamental changes in the way we live. a phenomenal rate—the number of described species is increasing by about Why Amphibia? 1–1.5 percent a year. And there are still hundreds, perhaps thousands, that have yet The decline of amphibians seems particular- to be discovered. Amphibians’ collective ly surprising, given that these creatures have domain includes every continent except been around for about 350 million years Antarctica, and probably most of the and were able to survive three mass extinc- world’s major islands. They achieve their tions. These events are thought to have greatest variety in tropical and warm tem- killed off approximately half of all animal perate forests. The neotropical realm is by species, including the dinosaurs that disap- far the richest; Central and South America peared 65 million years ago. Yet overall, house close to half of the world’s amphib- amphibians persisted when so many other ian species. But amphibians also live in groups of organisms did not.6 deserts, grasslands, northern bogs—even When amphibians first appeared, Earth’s tundra, in the case of the North American terrestrial area was essentially one giant wood frog, one of four species of North landmass inhabited by plants and insects. American frogs that can survive in a practi- Amphibians were the first vertebrates to cally frozen solid state.8 make the transition from water to land. Given their durability and ubiquity, the Somehow, a type of bony fish evolved into rapid decline of so many species is particu- a creature that had four legs, could breathe larly unsettling. Why are amphibians disap- atmospheric oxygen instead of dissolved pearing now? Many scientists claim that oxygen, and had a body structure that amphibians are important bioindicators—a allowed it to maneuver without the support sort of barometer of Earth’s health, since of water. It was these kinds of traits that laid they are more sensitive to environmental the groundwork for other classes of verte- stress than other organisms. One trait that brates—such as reptiles, birds, and mam- gives them this distinction is their mals—to develop.7 “amphibious” nature—the typical amphib- Since the first amphibian emerged from ian lifecycle is partly aquatic and partly ter- the water, the class has evolved into three restrial. That can make them doubly distinct groups (or, to use the scientific vulnerable: disturbance of either water or term, orders). Anura, which includes frogs land can affect them. In water, for example, and toads, is the largest group. The order some species have fairly narrow temperature Caudata includes salamanders and newts. requirements. Some do best in still water; And Gymnophiona, the least-known group, others need flowing water.9 which are commonly referred to as caecil- And many amphibians are particular ians, are legless, subterranean creatures that about where they will breed. In southwest- are found only in tropical and subtropical ern California, the endangered arroyo toad regions of the world. (See Table 4–2.) does not reproduce well unless it lays its

66 State of the World 2001 DECIPHERING AMPHIBIAN DECLINES

Ta b l e 4 –2. Global Distribution of Amphibians

Share of World’s Area Frogs and Toads Salamanders Caecilians Total Amphibia Amphibian Species (number of known species) (percent)

United States 90 151 — 241 5 and Canada

Central and South 2,135 248 82 2,465 50 America and the Caribbean

Eurasia and 103 89 — 192 4 North Africa

Sub-Saharan Africa 761 — 29 790 16

India, Southeast Asia 745 29 44 818 17

Australia, New 443 —— 443 9 Zealand, Papua New Guinea

Total 4,277 517 155 4,949

SOURCE: William E. Duellman,“Global Distribution of Amphibians: Patterns, Conservation, and Future Chal- lenges,” in William E. Duellman, ed., Patterns and Distribution of Amphibians: A Global Perspective (Baltimore, MD:The Johns Hopkins University Press, 1999), 3. For speciﬁc boundaries among areas, see page 6. eggs on the sandy bottom of a slow-moving result is not outright deforestation, logging stream. Some frogs and salamanders will lay can devastate amphibian populations. If eggs only in the shallow “vernal pools” that forests are allowed to regenerate, amphib- appear with the spring rains and disappear ians can return, although estimates of how with the summer heat. This is a kind of evo- long that will take vary; in the southeastern lutionary gamble with the weather: the United States, for example, the estimates young are safe from predatory ﬁsh in a ver- range from 20 to 70 years.11 nal pool, but they must reach their terres- Consider the logging boom in the U.S. trial phase before the pool dries up.10 Southeast, where forests shelter one of the Given such preferences, it is no surprise world’s richest assemblage of salamanders. that habitat degradation is the leading cause More than 65 percent of all salamanders of amphibian decline. Many amphibians, belong to a lineage called the Plethodonti- for example, are forest animals—and the dae, which lack lungs. These creatures world is currently losing approximately 14 breathe through their skin, which must million hectares of natural forest each year, remain moist at all times to facilitate gas an area larger than Greece. Even when the exchange or they will suffocate. Plethodon-

67 State of the World 2001 DECIPHERING AMPHIBIAN DECLINES

tids are consequently extremely sensitive to forest. In Florida, for example, approxi- changes in temperature and humidity. Even mately 80 percent of the natural longleaf selective logging is likely to reduce a popu- pine forest has been lost over the last 50 lation, because it opens up the canopy and years, and the majority of what was cleared dries out the forest floor. In the U.S. South- has been converted to commercial slash east, the logging of mature hardwood for- pine plantations. This is considered to be a est, the primary salamander habitat, is primary reason why populations of the expected to overtake the hardwood growth threatened flatwoods salamander have rate by the close of the decade.12 declined or disappeared in recent decades. The longleaf pine forest was the primary The Oregon spotted frog has largely habitat for the salamander, which does not do well in the drier, more uniform condi- disappeared from its historical range in tions of the planted slash pine forest. In the heavily farmed Willamette River Valley. South Africa, tree plantations have also come at a cost to local amphibians. The Deforestation-induced losses are almost Matatiele wetland near Mtunzini was one of certainly far greater in the tropics, although the last remaining natural coastal wetlands generally far less is known about them. An in the country and home to more than 25 extreme case appears to be Sri Lanka. As species of frogs. But when an exotic tree recently as 1993, the island’s amphibian plantation was installed next to it, the water fauna was thought to comprise only 38 table dropped and the wetland dried up.14 species, but a recent five-year survey of the Amphibians also depend on many other remaining rainforest may have turned up as types of habitat, and unfortunately the many as 200 additional amphibian species grasslands, wetlands, and streambeds of the that are apparently endemic (though these world are not faring much better than the have not yet been formally described, nor forests. In California, the conversion of has the estimate been published in a peer- native grasslands to farms and suburban reviewed journal). Yet Sri Lanka has only developments is a leading reason for the 750 square kilometers of rainforest left; endangered status of the California tiger over the past 150 years or so, the island has salamander—at least 75 percent of the orig- lost approximately 96 percent of its original inal grassland habitat has been irretrievably rainforest cover. When survey researchers lost. And in the United Kingdom, the loss checked the records of naturalists who were of breeding ponds is a primary reason for exploring Sri Lanka before 1900, they the decline of all six native species. Most of found that more than half of the amphib- the world’s rivers are now under the control ians mentioned were no longer present. of dams that cause flooding, scouring, and Most of Sri Lanka’s surviving natural forests siltation—the kind of forces that are largely are legally protected, but they continue to responsible for the disappearance of the dwindle in the face of illegal logging, pri- endangered Arroyo toad from 75 percent marily for fuelwood.13 of its former range in California.15 It is true that in many parts of the world, Although habitat loss is the leading cause large tracts of new “forests” are being cre- of amphibian decline, it obviously cannot ated, but tree plantations do not generally account for the many large-scale disappear- provide an ecological substitute for natural ances that have taken place in protected

68 State of the World 2001 DECIPHERING AMPHIBIAN DECLINES areas like Monteverde and Yosemite— Fertilizers, which are used in far greater places that would seem to be about as close quantities than pesticides, may be creating to pristine as possible. And yet the amphib- problems we are even less prepared to ians in these areas are apparently reacting to counter. Some amphibians are very sensitive dramatic changes. But these are changes to the nitrogen compounds that typically that are hard to see, or that just do not leach out of artificially fertilized fields. For seem “unnatural.” example, researchers have discovered that Toxics are one threat that is difficult to tadpoles of the Oregon spotted frog are see, and there’s no question that amphibians poisoned by water with nitrate and nitrite are highly vulnerable to all sorts of pollu- levels low enough to pass the drinking tants. Because they breathe and even drink water standards set by the U.S. Environ- through it, amphibians have thin, permeable mental Protection Agency. (Nitrate and skin that readily absorbs contaminants. nitrite are compounds that soil microorgan- Their eggs lack protective shells and are isms make from synthetic nitrogen fertiliz- highly permeable as well. So it is hardly sur- er.) Many water bodies in the United States prising that in heavily industrialized areas, contain levels of nitrate that violate govern- pollution is frequently invoked as a cause for ment standards. If these are not taken seri- local declines. In some older centers of ously as a matter of public health, it seems heavy industry, the pollution is so intense unlikely—to say the least—that more strin- and pervasive that it’s a wonder there are gent standards will be mandated for the any amphibians left to study. Amphibian welfare of frogs. The Oregon spotted frog populations in much of Ukraine, for exam- has largely disappeared from its historical ple, appear to be under attack from heavy range in the heavily farmed Willamette metals, pesticides, aromatic hydrocarbons, River valley.18 acid rain, and radioactive waste.16 Pollution, like habitat loss, is thus clearly But pollution is taking a toll in healthy- a major factor in amphibian decline. But looking landscapes as well. In Britain, the even considering both stresses, many acidification of ponds is a contributing fac- declines remain unexplained. Not far from tor in the endangerment of the Natterjack the Willamette valley, in the Cascades toad. This toad is now nearly extinct in Range of Oregon, for example, the Cas- British lowland heath, a habitat that used to cades frog and the western toad are disap- support about half the species’ population pearing, even though their habitat has not in that country. (The toad is faring poorly been significantly disturbed or polluted. in Scandinavia too, but it seems to be in Researchers have found that these species better condition farther south.) California’s are the victims of another stress: increased Sierra Nevada range is losing many of its exposure to ultraviolet (UV) light, a conse- amphibians, and pesticide contamination quence of the depleted stratospheric ozone could be a factor. The pesticides malathion, layer, which filters much of the UV wave- chlorpyrifos, and diazinon have been length out of incoming sunlight. UV light detected in precipitation at altitudes as high can damage DNA and even kill cells. as 2,200 meters. The pesticides are not used Amphibians, with their naked skins and in the mountains themselves; they are pre- eggs, are particularly at risk. The Cascades sumably drifting up from the state’s heavily species may be losing their eggs to the extra farmed lowlands.17 UV exposure.19

69 State of the World 2001 DECIPHERING AMPHIBIAN DECLINES

It is possible that increased UV levels are frog has been introduced into ponds and injuring other amphibians as well, particu- marshes in many places around the world, larly at higher latitudes, where the ozone as food and fishbait. It is not very particular layer tends to be thinner. Unfortunately, about where it lives or what it eats. It will seasonal fluctuations probably increase try to swallow almost anything it can fit in amphibian vulnerability: in either hemi- its mouth—including other frogs. It can sphere, the ozone layer tends to be at its also compete aggressively with other species weakest during winter and spring, a period for food. In California, where it was intro- that overlaps with the egg-laying season for duced in the early 1900s, the bullfrog may most species. Amphibians at higher eleva- have contributed to the declines of several tions could be especially susceptible as well, species. In South Korea, where it was since the higher you go, the less atmos- imported for food in the early 1970s, the phere there is to filter out the UV. But subsequent loss of native frogs and other researchers have found that not all amphib- small creatures inspired a government- ians are especially sensitive to UV light, nor sponsored anti-bullfrog campaign, with are all of them exposed to appreciable hunting contests and bounty prizes.21 quantities of it. Another organism that is apparently Amphibians face another major pressure lurking in many forests and swamps may that, like UV light and pollution, is hard to be consuming far more amphibian species see. Introduced, non-native species are than bullfrogs or trout do. In the mid- often in plain view, but because they usual- 1990s, an unknown pathogenic fungus was ly look perfectly “natural,” it can be diffi- found to be infecting frogs in Costa Rica, cult to see them as a threat. Yet certain Panama, Australia, and the United States. non-native species frequently prey on Researchers in these places discovered the amphibians or out-compete them for food. pathogen separately, but as they began to In New Zealand, introduced rats are compare notes they realized that they were thought to have caused the extinction of dealing with the same suspect. several species of Leiopelma frogs. And in Between 1993 and 1997, Karen Lips, a the Yosemite region of California’s Sierra herpetologist studying amphibians in Costa Nevada, large-scale trout introductions Rica and Panama, discovered several dead have played a major role in the disappear- and dying frogs at her research sites—a rare ance or severe decline of five of the region’s find, since dead frogs are usually snapped seven native amphibians. Further south, in up quickly by scavengers. During this same California’s Santa Monica Mountains, the period, she also observed population col- recent spread of introduced mosquitofish lapses in several species, and in five out of (used widely to combat mosquitoes, but the seven Panamanian streams she moni- unfortunately they eat more than that) may tored, frogs simply vanished altogether.22 be depressing local populations of the Cali- Meanwhile, in Australia, researchers fornia newt and the Pacific treefrog.20 were beginning to wonder if an epidemic One invader that frequently injures disease might be responsible for the series amphibians is itself an amphibian: the bull- of declines and extinctions that occurred frog, native to the eastern United States. An along the east coast of the country in the aggressive, fast-growing species that can 1970s and 1980s. As with the Central reach a length of 15 centimeters, the bull- American declines, the victims were stream

70 State of the World 2001 DECIPHERING AMPHIBIAN DECLINES dwellers and had succumbed very rapidly— were in decline. In Australia, it has been traits suggestive of a highly virulent, water- traced back to 1978—to a treefrog collected borne pathogen. When researchers in southern Queensland.25 compared skin samples from Panamanian and Australian victims, they found them In the mid-1990s, an unknown infected by the same type of organism: one pathogenic fungus was found to be or more fungi of the phylum Chytridiomy- infecting frogs in Costa Rica, Panama, cota. That came as a surprise, since chytrid fungi are common pathogens of plants and Australia, and the United States. insects but had never before been reported to attack vertebrates.23 Even though our understanding of the In the United States, the fungus was first fungus has grown tremendously in the last noticed in 1991, when it started killing cap- few years, there seem to be more unan- tive arroyo toads in California. In 1996, the swered questions now than ever before. For toads’ disease was identified as the chytrid one thing, scientists do not yet know if fungus, which has since been found in the there is more than one new species of fun- wild in various places around the country. gus. Nor do they know how it kills its vic- In Illinois and Maryland, it has been tims. It may suffocate them by causing their encountered as an apparently benign infec- skin to thicken (amphibians breathe partly tion of stable frog populations: the infected through their skin), or it may produce tox- animals seemed perfectly healthy. But in ins. And there are plenty of other questions. 1999 and 2000, wildlife officials in the U.S. Where, for instance, did it come from? It Southwest discovered the fungus in low- may have been widespread for a long time, land leopard frogs outside Phoenix, Ari- and only recently detected, or it may have zona, and in boreal toads near Denver, had a restricted range but recently spread to Colorado. In both cases, they found large new regions of the world, where it is find- numbers of dead and dying animals. Both ing new host species.26 species have been in sharp decline, and the If the chytrid has been expanding its range fungus has become a prime suspect.24 to such distant parts of the world, what could Scientists are now wondering how many be moving it around? Some herpetologists other declines the fungus might explain. think it may have been brought into new ter- Could it have been behind some of the older rain on the boots of tourists. Others see a die-offs—events later marshaled as evidence likely conduit in the trade in aquarium fish, for global amphibian decline? In many parts and in amphibians themselves. In Australia, of the world, scientists are uncorking old some scientists suspect that the chytrid may specimen bottles, and in a few cases the have been transported across the continent chytrid has turned up. In Colorado, the on the skin of an infected frog that stowed chytrid has been found in a few preserved itself away in a box of fruit. And once the leopard frogs from the 1970s. It has also fungus arrives in an area, there are many ways been detected in museum specimens of the it could spread: it may be dispersed by local Yosemite toad and the Northern leopard people, for example, or by cattle. It can frog, collected from the California Sierra even be carried by birds and insects.27 Nevada and the Colorado Rockies, respec- Another hypothesis is that the fungus tively, during the 1970s when both species could be a well-established pathogen in

71 State of the World 2001 DECIPHERING AMPHIBIAN DECLINES

many parts of world, and that something is they had never occupied before. But the upsetting amphibian immune responses, golden toad lived on top of the range and making them more vulnerable to attack. had nowhere to go.29 After all, the chytrid is not the only pathogen It is possible that the changing climate led that has been implicated in amphibian to the toad’s demise, but some scientists see declines. A group of viruses called iridovirus- another, more ominous possibility in the es may have caused the tiger salamander team’s ﬁndings. Climate change could be die-offs in Arizona, Utah, Maine, and “overlapping” with disease: the stresses of a Saskatchewan. Iridoviruses have also trig- changing climate could make amphibians gered declines of the common frog and the more susceptible to infection. It is possible common toad in the United Kingdom.28 the fungus haunts Monteverde as well. Maybe the Monteverde declines are the In Costa Rica, 20 species have declined result of a kind of synergism between the or disappeared since the late 1980s— pathogen and the warming seas. including the famous golden toad. Climate change and spreading disease: both of these forces have a global reach and Why so much disease in so many places they could overlap in a number of ways— in so short a time? It is possible that scien- either simultaneously or in sequence. A tists are just ﬁnding more disease because change in the moisture regime, as at Mon- they are getting better at looking for it. Or teverde, or a change in water temperature it might be evidence that some widespread might weaken amphibian immune systems. stresses are throwing amphibian immune Warmer water might also affect a patho- systems out of kilter. gen’s virulence, or its capacity to move By the late 1990s, evidence for one such from one animal to another. Warmer air stress turned up in Costa Rica, where 20 temperatures might increase the range of species have declined or disappeared since insects that carry it. the late 1980s—including the famous gold- Infections are likely to combine with en toad. Working on the initial hunch that other types of stress as well. Excessive UV the declines may have had something to do exposure, like climate stress, could suppress with the weather, a group of climatologists amphibian immune systems. So could some and biologists led by Alan Pounds, head of forms of pollution. And some diseases Monteverde’s Golden Toad Laboratory for appear to have been spread through the Conservation, found strong evidence that introduction of infected game fish like the reserve’s cloud forest is losing its trout; in such cases, a new predator overlaps clouds. According to the researchers, local with a new disease.30 sea surface temperatures have risen since Other overlaps are also cause for concern. the mid-1970s, and that has tended to push Consider, for example, non-native species. the cloud bank higher. The mountain tops Organisms that are successful invaders are are bathed in the clouds less frequently, so often capable of tolerating very disturbed the forest is now somewhat drier. This conditions. If some kind of disturbance might account for the amphibian losses. injures the native amphibians but does an The theory is corroborated by bird obser- invader no harm, then the latter may gain a vations: some lowland, “cloud-forest-intol- level of dominance it might not otherwise erant” birds have moved upslope, into areas have achieved. In the Ural Mountains of

72 State of the World 2001 DECIPHERING AMPHIBIAN DECLINES

Russia, this mechanism has apparently need to know what their death will mean. allowed the introduced lake frog to displace Amphibian decline itself is a form of envi- some of the natives. The lake frog seems to ronmental degradation, since amphibians tolerate industrial pollution much better play critical roles in many ecosystems. Given than the natives do, so the local frogs have their sometimes secretive and inconspicu- been hit by a pollution-invasion overlap. In ous nature, it is easy to underestimate their the Yosemite region of California, a combi- importance. Many species are only seen in nation of introduced trout and a five-year large numbers when they are breeding or drought is considered to be responsible for emerging from streams or ponds after they the decline or disappearance of several have developed from their aquatic to terres- species. The trout reduced the amphibians’ trial stage. And in many parts of the world ranges to isolated patches, and that amphibians stay buried in forest soils or increased their vulnerability to the drought desert sand for several months at a time— that hit the area from 1987 to 1992.31 waiting out unfavorable weather. Overlapping factors may also be partly Despite their cryptic nature, amphibians responsible for the recent rash of amphibian sometimes outnumber—and may even col- deformities—although there is no evidence lectively outweigh—other classes of verte- that suggests a relationship between defor- brates in many temperate and tropical mities and the declines. In some places woodlands. In Shenandoah National Park, where deformities have been observed, sci- in the southeastern United States, the Red- entists believe the cause is a kind of parasitic backed salamander has been found at densi- flatworm called a trematode. As the trema- ties as high as 10 per square meter. Since tode is often carried by snails, there may be the park is a hotspot for salamander diversi- a connection between nutrient-rich waters ty, each square meter could well contain (for example, water receiving runoff from other salamander species too. In a New agricultural areas) that attract snails and Hampshire forest, scientists found that the trematode infections.32 total mass of salamanders alone was more Habitat loss, pollution, UV exposure, than double the mass of birds (even during non-native species, disease, and climatic the birds’ peak breeding season) and about instability—those are the stresses that we equal to the mass of small mammals.33 know or suspect are killing off so many of Because they are so numerous, amphib- the world’s amphibians. Perhaps there are ians play key roles in many aquatic and ter- other, as yet unidentified stresses as well. But restrial ecosystems. As tadpoles, they a simple inventory like this, dismal as it is, devour vast quantities of algae and other still does not adequately represent the threat plants. A Marsh frog tadpole, for example, because it does not account for the overlap can filter algae out of about a liter of water factor. Unfortunately, we have virtually no each day. In some small lakes and ponds, idea what the overlaps will eventually do. amphibians may be the most important animal regulators of algae and other plant Beyond the Declines growth. Algal growth is itself a primary reg- ulator of aquatic oxygen levels; the more The loss of amphibians demands our atten- algae a body of water has, the less oxygen it tion not just because we need to know why is likely to have.34 these animals are dying, but because we Increased algal growth has already been

73 State of the World 2001 DECIPHERING AMPHIBIAN DECLINES

observed in parts of the world where ble threat, according to Kirkland, was the amphibians have declined. In Ecuador, for “small boy.”37 example, algal growth rose in the streams Today amphibians get little more credit where a species of poison dart frog was than they did in Kirkland’s time, even once abundant. Karen Lips noticed though their usefulness is now much more the same phenomenon following the disap- evident. In the 1970s and 1980s, for pearance of several frog species from her instance, India and Bangladesh were study sites in Central America. This kind exporting large quantities of frog legs to of subtle ecological change is presumably Europe, the United States, and Japan as a occurring in many streams and ponds culinary delicacy. These harvests were around the world.35 intensive enough to virtually empty many On land, amphibians play an important large marshes of their frog populations. As role as consumers of vast quantities of the frogs disappeared, the insect popula- insects and other invertebrates. Some tions exploded. Crop damage increased and species also eat small reptiles, birds, and there was a rise in malaria infections. Frog mammals. A study of the Blanchard’s crick- exports were banned in India in 1979. In et frog in Iowa concluded that a small pond Bangladesh, a ban was passed in 1990, after population of 1,000 frogs would consume farmers realized that it was cheaper to pro- about 4.8 million insects and other arthro- tect frogs than to buy pesticides. Unfortu- pods per year.36 nately, however, there is still a substantial frog smuggling operation in the region.38 The loss of amphibians could mean In addition to their role as consumers of the loss of potential cures for many algae and insects, amphibians also support common ailments. the many different types of animals that prey on them. They are important in the diets of The pest control benefits of amphibians many birds, mammals, reptiles, and freshwa- have long been recognized. A Farmer’s ter fish. Some bats and snakes live exclusive- Bulletin of the U.S. Department of Agri- ly on amphibians. In California’s Sierra culture from 1915, for example, contained Nevada, for instance, there is a type of garter a paper entitled “The Usefulness of the snake that depends on three of the local American Toad” by entomologist A. H. amphibian species, two of which are in seri- Kirkland. After examining the stomachs of ous decline. If the garter snake goes into 149 toads, Kirkland determined that “inju- decline as well, that could affect the preda- rious insects” such as gypsy moths, tent tory birds that depend on it. The fate of rap- caterpillars, and may beetles made up 62 tors may be bound up in the fate of frogs.39 percent of the toads’ total diet. In one In both aquatic and terrestrial food stomach he found the remains of 36 tent webs, amphibians often play an important caterpillars; in another, 65 gypsy moth role in energy transfer and nutrient cycling. caterpillars. He estimated that over 90 days Some scientists refer to amphibians as a single toad could consume nearly 10,000 important “conveyor belts” of energy noxious insects. It was Kirkland’s hope that through the ecosystems in which they toads could receive better protection and occur. Compared with birds and mammals, use as a natural pesticide in farms and gar- amphibians are much more efficient in con- dens. At the time, the toad’s most formida- verting food into new tissue, so a substan-

74 State of the World 2001 DECIPHERING AMPHIBIAN DECLINES tial amount of the energy that enters an another. The bromeliads grow and die, but ecosystem through photosynthesis passes the community as a whole might remain through amphibians, who then are eaten by stable because of the frogs.41 foxes, snakes, and owls. Some studies have The loss of amphibians could also mean found that amphibians can also be a much the loss of potential cures for many com- better source of protein than birds and mon ailments. Amphibians are an incredibly mammals. A predator would be better off diverse group of organisms that we know eating a pound of frogs rather than a pound relatively little about. We do know that they of mice. And given their dual roles—aquat- are living chemical factories; amphibians ic juvenile stage and terrestrial adult stage— produce all sorts of powerful compounds, amphibians are often an important or they concentrate compounds found in “nutrient bridge” from water to land. their prey. This characteristic is frequently a Through them, the algae that might other- form of defense. Because amphibian skin is wise suffocate a pond becomes a part of the thin and permeable, it offers little physical terrestrial fauna.40 protection from attack or infection. So pro- But the role of amphibians is often far tection is often chemical instead. Many more subtle and complex than food web species produce antibiotics and fungicides. dynamics might suggest. Consider, for Some produce powerful poisons, which example, the tiny frogs that live inside the they advertise to predators with their bright tank bromeliads in the Brazilian Atlantic coloring.42 forest. Bromeliads are a type of plant com- These chemicals are a medical treasure, mon in tropical American forests; most of as many traditional cultures have recog- them look rather like the rosette of leaves nized. Pulverized toads, for example, have on the top of a pineapple, and most of them been used in traditional Chinese medicine are epiphytes—that is, they live in trees for a variety of ailments. And while tradi- instead of rooting directly in the soil. The tional remedies doubtless vary greatly in rosettes of tank bromeliads have an espe- their efﬁcacy, modern chemistry is substan- cially large central cavity that holds a pool tiating the power of many of the raw mate- of water in which many different organisms rials. Epibatidine, a compound with can live. Some of these “arboreal ponds” powerful painkilling properties, was discov- are quite substantial; one species of tank ered in a skin secretion from a small, bright- bromeliad can hold as much as 30 liters of ly colored Ecuadorian frog known as water. But each pool is isolated from all the Epipedobates tricolor. Today, U.S. pharma- others, and many of the inhabitants are ceutical giant Abbott Laboratories is devel- strictly aquatic. An effective dispersal mech- oping a synthetic compound related in anism is therefore essential to the survival of structure to epibatidine that is 200 times these communities, and this is the role that more powerful than morphine and does not the frogs play. Researchers studying these have that drug’s negative side effects, such communities in the Atlantic forest have as constipation, respiratory failure, addic- found a host of little animals—from crus- tion, and resistance to the desired pain- taceans to various types of worms— killing effects. Clinical trials of the attached to the skin of bromeliad-dwelling compound are under way. If it fulﬁlls expec- frogs. Apparently, the frogs are moving tations, the epibatidine analog would be a these creatures from one bromeliad to major advance for medicine—improving

75 State of the World 2001 DECIPHERING AMPHIBIAN DECLINES the lives of millions of people suffering disease, is involved. But there are still some chronic pain.43 major gaps in our understanding of the Another frog of interest is a large green issue. treefrog that is used in an extraordinary To begin with, there is an incomplete hunting ritual practiced by Indians in the picture of what is at stake. As eminent her- Amazon Basin. The Indians create “hunting petologist William Duellman recently magic” by applying a secretion scraped from noted, “the amphibian faunas of many parts live frogs to self-inflicted burns on the arms of the world remain essentially unknown, or chest. Following a coma-like sleep, the and the faunas in many other regions are far hunters awake and find they have increased from completely documented.” In South stamina and keener senses. Research on America, nearly one third of the amphibian compounds from this frog have yielded sev- species were discovered in just the last two eral novel compounds that are able to lower decades. And new species continue to be blood pressure, reduce pain, and provide discovered at a rapid rate. The parts of the antibiotic effects. One compound interacts world that contain the largest numbers of with a variety of receptor systems and has undiscovered amphibian species include the provided new insights into how the brain’s mountainous regions of South America and message-reading receptor systems work. Southeast Asia and the islands in the Indo- Whether or not these compounds are Australian Archipelago (Sulawesi, Sumatra, responsible for the “hunting magic” prop- and the Irian Jaya part of New Guinea). In erties experienced by the Amazonian Indi- New Guinea, the current estimate of the ans remains unknown.44 number of amphibian species is 200, but We have yet to learn even the most obvi- herpetologist Michael Tyler believes the ous lessons from some of these creatures. total is probably twice that. The tropics may The wood frog is able to tolerate tempera- harbor thousands of amphibian species not tures low enough to turn up to 65 percent yet known to science.45 of its body water into ice. It produces some In part, the gaps in our knowledge stem sort of natural antifreeze to keep the from the enormous geographical mismatch remaining water liquid, but how does this between the research capacity and the crea- system work? And what might we have tures themselves. Canada, for example, has learned from the gastric-brooding frog if it plenty of amphibian specialists, but not a had not disappeared from the rain forests of single endemic amphibian. On the other Australia? This and other secrets are now hand, Mexico, like most tropical countries, beyond reach. has a vast amphibian fauna and only a few herpetologists. Although a good deal is Reconceiving the Science known about the amphibians of the United States, Western Europe, Costa Rica, and It has been more than 10 years since the Australia, there is limited understanding of prospect of global amphibian decline first those of South America, Asia, or most attracted widespread scientific attention. African countries—places that house some We now understand some species and some of the richest diversity of amphibians in the localized areas very well. We have discov- world. (See Table 4–3.) And among the ered that a whole complex of threats, such tropical species already identified, many are as nitrogen pollution, climate change, and in the literature only by virtue of their orig-

76 State of the World 2001 DECIPHERING AMPHIBIAN DECLINES

Ta b l e 4 –3. Major Known Hotspots of Amphibian Diversity

Portion of original Amphibian diversity Hotspot Total species Share endemic area still intact per unit area (species per thousand square kilometers of (number) (percent) remaining intact natural vegetation)

Tropical Andes 830 73 25.0 2.6 Mesoamerica 460 67 20.0 2.0 Chocó-Darién- Western Ecuador 350 60 24.2 5.6 Atlantic Forest Region 280 90 7.5 3.0 Sundaland (western 226 79 7.8 1.8 half of the Indo- Malayan archipelago) Indo-Burma 202 56 4.9 2.0 Madagascar and Indian 189 99 9.9 3.2 Ocean Islands Caribbean 189 87 11.3 6.3 Brazilian Cerrado 150 30 20.0 0.4 Western Ghats and Sri Lanka 146 80 6.8 11.7 Guinean Forests of West Africa 116 77 10.0 0.9 Mountains of South- 85 60 8.0 1.3 Central China Philippines 84 77 8.0 3.5 Eastern Arc Mountains 63 52 6.7 31.5 and Coastal Forests of Tanzania and Kenya Mediterranean Basin 62 52 4.7 0.6

SOURCE: Russell A. Mittermeier et al., Hotspots: Earth’s Biologically Richest and Most Endangered Terrestrial Ecoregions (Mexico City: CEMEX, S.A. 1999), 34, 42, and 50. inal descriptions; in such cases, virtually Bangladesh, where amphibians were widely nothing is known of the animal’s ecology or abundant up until a few decades ago, even whether it still exists.46 although today most species are threatened In many parts of the world, amphibian throughout the country. Amphibians in research is frequently constrained by a lack Bangladesh are being decimated by habitat of funds—but not generally by a lack of loss, exposure to pesticides and fertilizers, interest. Consider the dire situation in and commercial exploitation. Some species

77 State of the World 2001 DECIPHERING AMPHIBIAN DECLINES

are even being ground up for poultry feed. understudied regions. There is also a need Yet researchers still have a very tenuous to coordinate research programs, make understanding of the country’s fauna. As information more accessible, and build a biologist Sohrab Sarker watches the amphib- global amphibian database. ians of his country disappear, he bemoans A key organization that has already the lack of funding for field studies. played a major role in informing many of “Amphibians in Bangladesh are not studied the world’s herpetologists and supporting scientifically,” he says, “there are many research efforts in developing countries is species that still need to be investigated and the Declining Amphibian Populations Task identification of some specimens has been Force (DAPTF). This was established in held up due to lack of relevant literature.”47 1991 under the auspices of the World Con- servation Union–IUCN’s Species Survival From Canada to New Zealand, a Commission. It encompasses a network of growing army of volunteers is over 3,000 scientists and conservationists in canvassing the world’s swamps and more than 90 countries and serves as a global “information clearinghouse” on forests, searching for amphibians. amphibian decline. The Task Force produces the newsletter Froglog, which is an In Ecuador, there is a similar need for important vehicle for communicating additional research. A little frog called the updates on research and conservation jambato used to be so common you could endeavors from all over the world. Current- find it in the backyards of Quito. But the last ly, the volunteer scientists who manage the time a jambato was seen alive was in 1988. Task Force are compiling a comprehensive Perhaps the frog fell victim to a fungus, pos- summary of the declines and a CD-ROM sibly the chytrid, but no one knows because database of all data available on amphibian there is no money to do the research.48 populations, declining or otherwise. Both An article in an April 2000 issue of of these will be available in 2002.50 Nature provides an excellent demonstration In 1999, the DAPTF helped organize a of how skewed the research is. It contains series of amphibian decline workshops in the most exhaustive overview of amphibian Mexico, Panama, and Ecuador. The orga- population trends to date. To produce it, a nizers hoped the meetings would be the first team of researchers combed through the sci- in a series of efforts to coordinate and build entific literature and coaxed additional data amphibian research in the region. Given the out of more than 200 scientists in 37 coun- level of participation—the workshops drew tries. Of the 936 populations the team man- in 88 people from 13 countries—that seems aged to cover, 87 percent were in Western like a reasonable expectation.51 Europe or North America, 5 percent were The Internet is also providing new and in Central and South America, 2 percent speedy ways for researchers to communi- were in Asia, and less than 0.5 percent were cate and contribute to global databases. in Africa and the Middle East.49 The recently launched Amphibiaweb is a Moving into the second decade of inves- site dedicated to providing information on tigating amphibian declines, it will be essen- all the world’s known amphibian species. tial to fill the gaps in our understanding and Each species will have its own “home support research and conservation efforts in page,” including species description, life

78 State of the World 2001 DECIPHERING AMPHIBIAN DECLINES history traits, conservation status, and liter- social sciences and possibly even the ature references.52 humanities. “To understand this problem Acquiring more information will get us we have to do a better job of integrating only so far. Once the information is collect- humans into ecological and evolutionary ed, it must be used in the most effective way theory,” he argues. “The nature of science possible. For this, it will be necessary to itself is going to have to change.”53 change the way the science is done. The But the new research paradigm cannot declines cannot readily be contained in a be just a matter of linking scientists togeth- single field of inquiry. They involve micro- er. Because the problem is so pervasive, sci- scopic pathogens and global climate ence is going to need to build a community change; they are part of forestry economics of serious amateurs—members of the gen- and wildlife toxicology. Understanding eral public who can become “citizen scien- them will require a much more interdiscipli- tists.” A volunteer amphibian monitoring nary, integrative approach than is typical of movement is already gaining steam. From conventional research. Instead of individual Canada to New Zealand, a growing army of specialists working on problems indepen- volunteers equipped with amphibian identi- dently, research programs will have to find fication tapes, field guides, flashlights, pen- ways to focus the efforts of many disciplines cils, and waterproof notepads is canvassing into a collaborative whole. Some of the the world’s swamps and forests, searching most successful recent work is already mov- for amphibians. From schoolchildren to ing in this direction—the climate research at retirees, these people are heading out in Monteverde, for example, or the interna- evening hours, listening for frog calls, and tional investigation of the chytrid fungus. keeping careful records of what they hear That idea is beginning to resonate with- and see. in some major scientific institutions, such as One of the largest volunteer networks is the National Science Foundation, the U.S. the North American Amphibian Monitor- government body that is the chief source of ing Program (NAAMP). The program federal funds for scientific research. In began in the mid-1990s, and by 1999 hun- 1999, the agency awarded $3 million to a dreds of volunteers were working in 25 team of 24 scientists from fields as diverse as states. They are trained to identify their veterinary epidemiology and evolutionary local amphibian fauna and follow a stan- ecology to study host-pathogen relation- dardized monitoring protocol. The data ships as an aspect of amphibian decline. Jim they collect become part of a global pool of Collins, the Arizona State University biolo- information that is being used to gain a bet- gist who heads the team, explained the ter understanding of amphibian declines. challenge this way: “As we went through Indicative of the extent of this effort, in thinking about how to answer the ques- Minnesota the program has sold more than tions, we really had to think about how we 1,000 copies of its amphibian audio tape, did the science. And how we did the science and its well-tuned volunteers have covered had to change—it couldn’t be just an indi- 150 monitoring routes since 1993. In vidual investigator laboring away in an iso- Maine, NAAMP volunteers monitor 60 lated laboratory.” Collins emphasizes the routes; Texan volunteers cover 20 routes.54 need for interaction not just between differ- In many cases, volunteers see animals ent biological disciplines, but also with the they have never seen before. A participant

79 State of the World 2001 DECIPHERING AMPHIBIAN DECLINES in a Massachusetts program commented they head toward roads. Once the migrants that she had lived in her town for her entire have been detained at the base of the fence, life and “had no idea that each spring hun- volunteers capture them and ferry them to dreds of salamanders crossed through her safety. A “toad patrol” squad at one road backyard.” Massachusetts volunteers are crossing in England rescued more than also involved in identifying vernal pools— 4,500 toads in just one season. At the same the shallow, seasonally flooded wetlands crossing, more than a thousand toads were that provide critical breeding sites for many killed by motorists.57 amphibians. Since the late 1980s, local citi- In addition to providing crucial informa- zens have helped identify a good portion of tion about population trends, migration the 1,200 vernal pools that are now pro- patterns, and breeding sites, the new trend tected by the state.55 in “citizen science” is providing something Another monitoring network is under that may be even more significant. By get- development in Central America. Modeled ting people out into the woods and swamps on NAAMP, the Maya Forest Anuran Mon- and attuned to their local fauna, the volun- itoring Project (MAYANMON) was initiat- teer programs could serve as a way to cap- ed in 1997 to monitor amphibians in the ture the public’s imagination and develop Maya Forest region. Today, the program is bigger constituencies for conservation sci- a tri-national effort, with sites in Belize, ence. Amphibian decline is kind of a case Mexico, and Guatemala. It plans to add study of unsustainability, touching on all additional countries soon. Like NAAMP, the major environmental issues of our day. this is a volunteer program based on It could serve as an important catalyst for regular, standardized monitoring of numer- change on these issues. ous sites. The information collected will be critical for the development of baseline data for an area that has not been well Protecting Amphibians studied. Thus far, all participants are biologists, but MAYANMON recently received There are clearly many impressive and a grant to train local Mayan villagers promising initiatives under way that bode who have an interest in monitoring the eco- well for the future of amphibian research. logical health of their surroundings. The But will the evidence ever translate into MAYANMON project is the first of its kind sweeping changes in conservation policy? to be undertaken in Central America, and it Considering amphibian decline as a political represents a unique example of internation- issue, it is almost inconceivable to imagine al cooperation.56 an international treaty to prevent frog Many European countries have encour- extinctions. Amphibian decline lacks the aged volunteer efforts to reduce road traffic political “weight” of issues like climate mortality. Beginning in the 1960s, conser- change. True, some countries do have vationists initiated programs to reduce explicit policies protecting amphibians— amphibian roadkills by informing motorists, but these vary greatly around the world, installing “toad-crossing” traffic signs, and and as is clear from the current trend in setting up detours during peak migration amphibian populations, they are not entire- times. More recently, drift fences have been ly effective. used to capture migrating amphibians as In the United States, the Endangered

80 State of the World 2001 DECIPHERING AMPHIBIAN DECLINES

Species Act (ESA) is the only law that pro- amphibians. The Convention on Interna- vides direct protection for amphibians. tional Trade in Endangered Species of Wild Since its inception in 1973, 18 frog, toad, Fauna and Flora (CITES) controls trade in and salamander species—out of 194 identi- numerous endangered plant and animal fied in the country—have been listed as species. (See Chapter 9.) As of 2000, 81 threatened or endangered under ESA. amphibian species were protected under Species listed under ESA receive special CITES. But the focus of CITES is on protection, primarily in the form of a “take” restricting international trade, not on pro- prohibition that makes it unlawful for a per- viding on-the-ground protection within a son to kill or injure a listed species—this can country’s borders.61 include any significant habitat alteration or As laudable as ESA and CITES are, such degradation that kills or injures the species. species-specific approaches are not enough Other recovery strategies, such as captive to slow the current pace of global amphib- breeding and reintroductions, are also fre- ian declines. Beyond the fact that they apply quently used.58 to just a tiny fraction of the world’s Over 27 years ESA has been successful in amphibian species, these strategies are not rescuing several amphibian species from the effective for several reasons. For one thing, brink of extinction. And it has provided many species are going extinct that are not many indirect benefits through the protec- on any lists at all. They are disappearing in tion of habitats—wetlands or forests that remote areas of the world where the are saved for amphibians clearly provide amphibian faunas are not well understood. many important services beyond being In addition, many of the declines and dis- homes for frogs. But there are also some appearances have taken place in just a year pitfalls associated with ESA. For one thing, or two—far too quickly to do the paper- it can take years for the listing to be work for listing under laws like ESA or approved once a petition has been filed. CITES. And finally, even if species such as The Santa Barbara County population of these had been protected under an endan- the California tiger salamander, for exam- gered species law, it probably would have ple, finally received permanent listing as made no difference. They already lived in endangered under ESA in September highly protected areas. The Monteverde 2000—eight years after the listing petition Cloud Forest is one of the world’s premier was submitted and 15 years after the species parks, and home to expert biologists who was first recognized as a candidate. In those monitor the local fauna very closely. Aside 15 years, more than half of the population’s from a last-ditch effort at captive breeding known breeding sites were destroyed.59 (which was attempted with the gastric- Denmark, France, Germany, Luxem- brooding frog), there was no obvious way bourg, and the Netherlands also have legis- these losses could have been prevented by lation protecting all amphibians. But in the time they were detected. other European countries, there is no pro- Given the magnitude of the threats at tection. As in the United States, formal pro- play, it is obvious that a species-by-species tection of amphibian species usually entails approach is just not going to work. The some form of habitat protection.60 problem of amphibian declines is teaching There is one international treaty that us an important lesson about the way we provides some specific protection for approach environmental issues in general.

81 State of the World 2001 DECIPHERING AMPHIBIAN DECLINES

While it is certainly reasonable to argue for tect forests, wetlands, and other essential more money and research and conservation, habitat; to reduce the spread of non-native and to demand more powerful conservation species; to improve farming practices so policies, the painful fact is this: no amount that farmers don’t depend on heavy inputs of money or legislation is going to make this of pesticides and fertilizers; and to reduce problem go away—if it is directed only at the emissions of greenhouse gases that con- this problem. What is happening to amphib- tribute to climate change. Clearly, the ben- ians reﬂects what is happening to the planet eﬁts of these changes will be felt far beyond in general. If we don’t address the underly- frogs and salamanders. They will have faring reasons for amphibian decline, there is reaching impacts on ecosystems and human no way we can save these species. health in general. Ultimately, the survival of While efforts to protect particular species amphibians and other creatures will depend are important, amphibians show us that on our willingness to confront the major, what really matters are the initiatives to pro- systemic environmental issues of our day.