Download MONTEVERDE GOLDEN TOAD Remaining Population: Unknown

« Return to Vanishing
MONTEVERDE GOLDEN TOAD
Remaining Population: Unknown
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Range: Costa Rica
This small tropical toad is more glamorous and mysterious than it
seems an amphibian could be. Its glamour is nature-made but its
mysterious decline probably is due to humans. Golden toads have
never been widespread, but they used to be abundant in a handful of
areas of cloud-shrouded tropical forest above the Costa Rican town of
Monteverde. No one has seen a golden toad since 1989.
Species Description and Range
The Monteverde golden toad was first described in the 1960s in a
scientific paper entitled "An Extraordinary New Toad from Costa Rica."
Extraordinary, it is! The males, just barely two inches (5 cm) long, are
an unbelievably bright orange. Unlike most toads, their skin is shiny
and brilliant. A renowned herpetologist was so surprised upon first
seeing them that he said it appeared as if they had been "dipped in
enamel paint." The females look different, but just as spectacular.
Slightly larger than the males, females are dark olive to black with
spots of scarlet encircled by yellow.
Natural History
Very little is known about golden toad behavior. In the Monteverde
forest, golden toads were conspicuous only during the breeding
season. For a few weeks each April, the males gathered in groups of
hundreds in small pools of water to wait for females. Breeding activity
lasted a week or two, then the toads would disappear for another year.
The eggs were laid in seasonal water catchments, where the tadpoles
would hatch and grow into adults in a very short time.
In 1987, the golden toad was closely studied by an American ecologist
and herpetologist who, by chance, happened upon its breeding
spectacle. She described it as brief and breathtaking; the males looked
like "little jewels on the forest floor." She was so fascinated that she
applied for a grant to return and study the toads.
In 1988, no toads appeared when the seasonal rains started. During
several months of searching the Monteverde forest, scientists found
only ten golden toads, and none were breeding. In 1989, only one
lonely toad was found where once there were hundreds. Despite much
searching, not a single golden toad has been seen since then.
The golden toad is an amphibian, the group of animals that includes
frogs, toads, and salamanders. Among the oldest creatures on earth,
amphibians first appeared some 350 million years ago. They are
characterized by a complex biology, which includes life both in the
water and on land. Most amphibians begin life as eggs, laid in or near
water, and hatch into free-swimming young, then they grow into airbreathing adults (see metamorphosis). Amphibians have lungs for
breathing, but they also have the ability to absorb oxygen through
their skin.
Distributed worldwide, amphibians are adapted to a variety of habitats
and lifestyles. Some climb trees, some burrow underground, and
others live an entirely aquatic life. They can be found from tropical
forests, to wetlands, to mountain tops, to deserts. They range in size
from giant ten-pound (4.5 kg) toads to the tiniest of tree frogs.
Wherever they occur, amphibians play a key role in the natural
ecosystem. They are important both as predators, eating huge
numbers of insects and other small creatures, and as prey for larger
animals, including fish, birds, mammals, and reptiles. Like reptiles,
amphibians are cold-blooded, which means their body temperature is
about the same as the temperature in the surrounding environment.
Amphibians bask in the sun to keep warm, and some burrow or
hibernate to escape very cold, hot, or dry weather.
Humans and Amphibians
Frogs and toads have been featured in the folklore and mythology of
many cultures. Ancient Aztecs believed that toads were guardians of
the underworld. Chinese and Indian mythology describes a threelegged frog that holds up the world and causes earthquakes when it
moves. Frogs and toads are popular characters in literature and are
often depicted as wise or clever creatures.
Humans have long used frogs as food. We are only beginning to
understand the potential medicinal uses of amphibians. For example,
not all poison-dart frogs are toxic; one brilliantly-colored frog secretes
a chemical that may be useful as a cardiac stimulant for heart-attack
patients, and another produces a powerful painkiller which may some
day be an alternative to morphine.
Causes of Endangerment
Amphibians in general are particularly sensitive to changes in their
habitat and in climate because they live both on land and in water,
they are both predators and prey, and they have permeable skin.
Many factors appear to be interacting to cause their decline.
Habitat Loss
Habitat destruction and alteration has taken its toll on amphibians.
Worldwide, ponds, rivers, and marshes have been drained, diverted,
and polluted; recreational lakes are stocked with non-native fish or
frogs that out-compete or prey on native species; forests are logged or
converted to cropland or pasture; and human development obliterates
other amphibian habitats. In Guatemala, home to 120 amphibian
species, 50 to 75 percent of the rainforest has been clearcut or burned
in the last 15 years. Those animals not killed outright are left with no
natural habitat.
Habitat destruction does not explain the disappearance of the
Monteverde golden toad, however. The high-elevation rain forest
where it lived is a relatively pristine area, protected as a national
reserve since the 1970s.
Worldwide Decline in Amphibians
The unexplained, sudden disappearance of the golden toad is not a
unique story. Populations of frogs, toads, and salamanders are
declining or disappearing the world over. In the late 1980s the
scientific community first took notice of this alarming trend, which
continues today.
Recent examples of this phenomenon include the reported decline of
whole communities of frogs in areas as different and far apart as a
National Park in the western United States and the montane rain forest
of eastern Australia. In the Australian rain forest, at least 14 species of
stream-dwelling frogs have disappeared or declined sharply (by more
than 90%) during the past fifteen years, according to a report
published in April 1996. These precipitous declines are widespread
across a large area of rain forest, suggesting that habitat destruction
by itself is not a likely cause.
In Yosemite National Park in the United States, scientists recently
discovered the large-scale collapse of an entire community of
amphibians. Surveys conducted in 1992 revealed that all seven native
species of frogs and toads in the region of Yosemite have declined
since 1915. Three species have disappeared entirely from this nearly
pristine National Park. Researchers found only one western toad, which
was once described as being "exceedingly abundant." The only species
that was reported to be more widespread is the one non-native
species, the bullfrog, which was introduced to the area in the late
1800s.
Amphibians are now the object of intensive studies to solve the
mystery of their decline. Where habitat destruction is not the obvious
cause, it is thought that other, less-visible problems, such as pollution,
acid rain, drought, disease, human exploitation, and ozone depletion
may be killing the animals.
Overexploitation
Amphibians are part of the diet of many local peoples around the
world. A low level of subsistence hunting rarely decimates a
population. The recent rise in commercial utilization of frogs, however,
has been deleterious. As close-to-home sources of frogs became
scarce, Indonesia and other tropical areas have been feeding the
tremendous appetite for frog legs in Europe. Demand is also growing
in the United States. Between 1981 and 1984, the United States
imported more than 6.5 million pounds (3 million kg) of frog meat
each year, representing the death of approximately 26 million frogs.
Most of these were harvested from the wild.
Frogs and toads are also killed for their hides. In Brazil, toads are
fashioned into purses, and in Thailand, street vendors sell wallets
made from frog skin. The capture of frogs and toads for the pet trade
also has increased in recent years.
Pollution/ Pesticides
Amphibians absorb industrial and agricultural pollution from the air,
soil and water. In addition, most amphibians eat huge amounts of
insects, which often carry pesticides. Each year, farmers and
gardeners in the United States buy more than 1 billion pounds (454
million kg) of pesticides to spray on their lawns and gardens. In other
places, like South America, chemicals banned in the United States are
regularly used to increase yields from crops grown on poor soils. Not
far from the home of the golden toad in Costa Rica, banana farmers
liberally apply dangerous pesticides, to produce flawless bananas for
markets in the United States.
Acid Rain
Industrial pollution raining down from above causes the acidification of
certain surface waters, even lakes and streams that seem far removed
from human influence. Amphibians and their eggs are often the first
animals to be affected by even slight changes in water pH. In some
studies, amphibian eggs subject to acid conditions failed to develop.
Because acid rain can fall hundreds of miles from the source of the
pollution, its effects are being felt in areas otherwise undisturbed by
humans.
Climate Change
In the last two-hundred years, people have burned fossil fuels and cut
down or burned forests at alarming rates. The resulting global
warming has increased the Earth's average surface temperatures and
disrupted natural processes such as precipitation. Amphibians are
sensitive to even slight changes in water temperature and their waterdependent reproduction can be devastated by drought or an ill-timed
storm. Unusually low rainfall in the two years before the reported
disappearance of the Monteverde golden toad may have caused
seasonal breeding ponds to dry up early, killing the toad eggs or
young. Although amphibians have survived millions of years of
weather change, including Ice Ages, it is thought that these humancaused climate changes are occuring too fast for amphibians to adapt.
Ultraviolet Radiation
A new theory on amphibian decline points to increased ultraviolet
radiation (UVR) from the sun. High levels of UVR, such as might be
caused by ozone depletion, have been shown to retard reproduction
in amphibians and cause cancer. Populations of several frog species
found in mountain habitats have declined dramatically. These highelevation species bask in the sun and are dark in color, adaptations to
help keep the animals warm in cold conditions. These same tendencies
may cause greater absorption of harmful radiation.
Introduced Species
Researchers in Yosemite National Park surmise that introduced trout
and bullfrogs have contributed to the decline of native amphibians.
When the Park was first formed, sport-fishing enthusiasts stocked
trout in many lakes which had no natural fish populations. Trout are
both a predator of and competitor with the native frogs. The fish eat
amphibian eggs and larvae and also eat the same insect prey as adult
frogs. The bullfrog (Rana catesbeiana), native to eastern North
America, was widely introduced in the western United States in the
late 1800s, presumably to increase available supplies of frog legs for
restaurants. The bullfrog, which has thrived and spread, is known to
eat and out-compete native frogs.
Disease
For amphibian populations already stressed by pollution, habitat loss,
or other factors, the introduction of a new disease can be deadly.
Scientists suggest that the mass disappearance of frogs seen in the
Australian rain forest may be due to an epidemic of an exotic disease.
The increasing trade in plants and animals for aquariums may be
transporting between continents diseases to which amphibians are
particularly susceptible. Viruses or bacteria which may not be
dangerous in their country of origin can be lethal to animals which
have never encountered them before.
Conservation Actions
Perhaps amphibians are the "canary in the coal mine," giving us early
warning of the deterioration of our environment. If amphibians are the
biological indicators of the world's health, we need to pay attention to
what they're telling us.
Its beauty and rarity earned the golden toad fame rarely achieved by
amphibians. It was used as a public relations symbol in the United
States to raise money to purchase and protect its habitat, creating the
Monteverde Cloud Forest Preserve in 1972. Although this action
seemed to secure the toad's future, it is now apparent that setting
aside habitat is not enough to save most endangered species.
Amphibians continue to decline worldwide. Although the mystery has
not been solved, it is likely due to a combination of causes.
Amphibians will benefit from conserving tropical rainforests and other
rare habitats, including wetlands, as well as strict controls on wild
capture of frogs for restaurant consumption or the pet trade. Reducing
pesticide use and controlling the pollution that causes global warming
will also help amphibians. It may be too late to save the Monteverde
golden toad, but it is hoped that stepped-up research efforts will save
other amphibians from the same fate.
A major step in protecting endangered amphibians is recognition of
their plight. CITES Appendix I and II includes just ten species of frogs
and toads for regulation of trade. Most of these are species sought
after for meat. The majority of amphibians affected by the pet trade
are not yet protected under CITES. Few countries have targeted
amphibians for protection. However, 12 domestic species of frogs and
toads are listed under the Endangered Species Act (ESA) in the United
States. The most recent addition is the California red-legged frog,
listed as "threatened" under the ESA in May 1996. This frog, made
famous by Mark Twain in The Celebrated Jumping Frog of Calaveras
County, has disappeared from 70 percent of its former range. The
listing is significant also because it is the first species of a backlog of
500 to be listed after the lifting of a year-long moratorium imposed by
Congress.
Questions for Thought
Unlike beautiful birds and furry mammals, toads are not inherently
appealing to most people. Why should we be concerned about the
disappearance of one geographically-limited amphibian, like the
Monteverde Golden Toad?
The Monteverde Golden Toad may live up to 12 years. No golden toads
have been seen in the last seven years. Is it too early to say they are
extinct?
CITES will not officially list a species as extinct until 50 years have
passed since the last confirmed sighting. Is this standard appropriate
for short-lived species like the golden toad? How might this standard
affect golden toad conservation?
Activities: [CS1-1, CS1-3, CS2-2, General]
Words in bold italics can be found in the glossary.
All Rights Reserved. Edition date 07/02/96.
All content © 2005 by Craig Kasnoff. Site design © 2005 by Westside Creative. All
Rights Reserved.