Golden toad
Encyclopedia
The golden toad was a small, shiny, bright true toad
that was once abundant in a small region of high-altitude cloud-covered tropical forests, about 30 square kilometers in area, above the city of Monteverde
, Costa Rica
. For this reason, it is sometimes also called the Monteverde golden toad, or the Monte Verde toad. Other common English names include Alajuela
toad and orange toad. They were first described in 1966 by the herpetologist Jay Savage. Since May 15, 1989, not a single B. periglenes is reported to have been seen anywhere in the world, and it is classified by the IUCN as an extinct species
. Its sudden extinction might have been caused by chytrid fungus and extensive habitat loss.
." Exhibiting sexual dimorphism
, female toads were slightly larger than the males, and looked very different. Instead of being bright orange, females were colored dark olive to black with scarlet spots encircled by yellow.
s.
Males outnumbered females, in some years by as much as ten to one, a situation that often led bachelors to attack amplectant pairs and form what Savage once described as "writhing masses of toad balls." The eggs of the golden toad, black and tan spheres, were deposited in small pools--puddles--often no more than one inch deep. Tadpoles emerged in a matter of days, but required another four or five weeks for metamorphosis. During this period, they were highly dependent on the weather; too much rain and they would be washed down the steep hillsides, too little and their puddles would dry up. Golden toads were always found at an altitude of between forty-nine hundred and fifty-six hundred feet.
In 1987, an American
ecologist and herpetologist, Martha Crump
, was fortunate enough to see the toad's mating rituals. In her book, In Search of the Golden Frog, she described it as "one of the most incredible sights I've ever seen," and said they looked like "statues, dazzling jewels on the forest floor." On April 15, 1987, Crump recorded in her field diary that she counted 133 toads mating in one "kitchen sink-sized pool" that she was observing. Five days later, she witnessed the pools in the area drying, which she attributed to the effects of El Niño-Southern Oscillation
, "leaving behind desiccated eggs already covered in mold
." The toads attempted to mate again that May. Of the 43,500 eggs that Crump found, only twenty-nine tadpole
s survived the drying of the forest's ground.
Jay Savage first discovered the toads in 1966. From their discovery in 1966 for about 17 years, and from April to July in 1987, over 1500 adult toads were seen. Only ten or eleven toads were seen in 1988, including one seen by Crump, and none has been seen since May 15, 1989, when Crump last saw the same solitary male toad that she had seen the year before.
In the period between discovery and disappearance, the golden toad was commonly featured on posters promoting the biodiversity
of Costa Rica. There is a single anecdotal report from the 1970s of a golden toad in the mountains of Guatemala
near the village of Chichicastenango
, but this sighting has not been confirmed. There is also another extinct frog sometimes compared to the golden toad found in the same forest in Costa Rica, named Holdridge's Toad
.
Jennifer Neville has examined the different hypotheses explaining the extinction of the golden toad in her article "The Case of the Golden Toad: Weather Patterns Lead to Decline". Neville comes to the conclusion that Crump's El Niño hypothesis is "clearly support[ed]" by the available data. IUCN gives numerous possible reasons in its description of the past threats to the species, including "[the golden toad's] restricted range, global warming
, chytridiomycosis
and airborne pollution
". Neville also mentions arguments that an increase in UV-B radiation, fungus
or parasites
, or lowered pH
levels contributed to the Golden Toad's extirpation.
A more recent study confirms the El Niño hypothesis, in which it is stated that "The new study finds that Monteverde was the driest it’s been in a hundred years following the 1986-1987 El Niño, but that those dry conditions were still within the range of normal climate variability". The new study has shown that the Chytrid Fungus
has spread due to the dry conditions caused by El Niño.
True toad
Bufonidae is the family of the true toads, members of the order Anura . They are the only family of anurans all members of which are known as "toads." The bufonids now comprise more than 35 genera, Bufo being the most widespread and well known.-Characteristics:True toads are widespread and occur...
that was once abundant in a small region of high-altitude cloud-covered tropical forests, about 30 square kilometers in area, above the city of Monteverde
Monteverde
Monteverde, Costa Rica is a small town in Puntarenas, Costa Rica. Located in the Cordillera de Tilarán, roughly a four hour drive from the Central Valley of Costa Rica, Monteverde is considered a major ecotourism destination in Costa Rica...
, Costa Rica
Costa Rica
Costa Rica , officially the Republic of Costa Rica is a multilingual, multiethnic and multicultural country in Central America, bordered by Nicaragua to the north, Panama to the southeast, the Pacific Ocean to the west and the Caribbean Sea to the east....
. For this reason, it is sometimes also called the Monteverde golden toad, or the Monte Verde toad. Other common English names include Alajuela
Alajuela
Alajuela is the second largest city in Costa Rica after the capital, San José. It is also the capital of the namesake province. Because of its location in the Costa Rican Central Valley, Alajuela is nowadays englobed in the conurbation of Great Metropolitan Area...
toad and orange toad. They were first described in 1966 by the herpetologist Jay Savage. Since May 15, 1989, not a single B. periglenes is reported to have been seen anywhere in the world, and it is classified by the IUCN as an extinct species
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
. Its sudden extinction might have been caused by chytrid fungus and extensive habitat loss.
Description
The golden toad was one of more than 500 species in the family Bufonidae — the "true toads". B. periglenes inhabited northern Costa Rica’s Monteverde Cloud Forest Preserve, distributed over an area of roughly 10 square kilometre at an average elevation of 1.5 kilometre (0.93205910497471 mi).Morphology
Adult males measured just barely 5 centimetres (2 in) long. Males have been described as being "Day-Glo golden orange", and unlike most toads their skin was shiny and bright. Jay Savage was so surprised upon first seeing them that he did not believe they could be real; he is quoted as saying: "I must confess that my initial response when I saw them was one of disbelief and suspicion that someone had dipped the examples in enamel paintEnamel paint
Enamel paint is paint that air dries to a hard, usually glossy, finish, used for coating surfaces that are outdoors or otherwise subject to hard wear or variations in temperature; it should not be confused with decorated objects in "painted enamel", where vitreous enamel is applied with brushes and...
." Exhibiting sexual dimorphism
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
, female toads were slightly larger than the males, and looked very different. Instead of being bright orange, females were colored dark olive to black with scarlet spots encircled by yellow.
Reproduction
Very little is known about the behavior of B. periglenes; however, it is believed that they lived underground, as they were not seen for most of the year. In contrast, their presence in the Cloud Forest Preserve was obvious during their mating season, which lasted only a few weeks. For a few weeks in April, after the dry season ended and the forest became wetter, males would gather in large numbers near ground puddles and wait for the females. The males would fight with each other for opportunities to mate until the end of their short mating season, after which the toads retreated to their burrows. Eggs were laid in seasonal water catchments in clutches, the average size of which was 228 eggs. After two months, they hatched into tadpoleTadpole
A tadpole or polliwog is the wholly aquatic larval stage in the life cycle of an amphibian, particularly that of a frog or toad.- Appellation :...
s.
Males outnumbered females, in some years by as much as ten to one, a situation that often led bachelors to attack amplectant pairs and form what Savage once described as "writhing masses of toad balls." The eggs of the golden toad, black and tan spheres, were deposited in small pools--puddles--often no more than one inch deep. Tadpoles emerged in a matter of days, but required another four or five weeks for metamorphosis. During this period, they were highly dependent on the weather; too much rain and they would be washed down the steep hillsides, too little and their puddles would dry up. Golden toads were always found at an altitude of between forty-nine hundred and fifty-six hundred feet.
In 1987, an American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
ecologist and herpetologist, Martha Crump
Marty Crump
Marty Crump is a behavioral ecologist who works with tropical amphibians in the areas of parental care, reproduction, territoriality, cannibalism, and tadpole ecology...
, was fortunate enough to see the toad's mating rituals. In her book, In Search of the Golden Frog, she described it as "one of the most incredible sights I've ever seen," and said they looked like "statues, dazzling jewels on the forest floor." On April 15, 1987, Crump recorded in her field diary that she counted 133 toads mating in one "kitchen sink-sized pool" that she was observing. Five days later, she witnessed the pools in the area drying, which she attributed to the effects of El Niño-Southern Oscillation
El Niño-Southern Oscillation
El Niño/La Niña-Southern Oscillation, or ENSO, is a quasiperiodic climate pattern that occurs across the tropical Pacific Ocean roughly every five years...
, "leaving behind desiccated eggs already covered in mold
Mold
Molds are fungi that grow in the form of multicellular filaments called hyphae. Molds are not considered to be microbes but microscopic fungi that grow as single cells called yeasts...
." The toads attempted to mate again that May. Of the 43,500 eggs that Crump found, only twenty-nine tadpole
Tadpole
A tadpole or polliwog is the wholly aquatic larval stage in the life cycle of an amphibian, particularly that of a frog or toad.- Appellation :...
s survived the drying of the forest's ground.
Conservation history
In the period between discovery and disappearance, the golden toad was commonly featured on posters promoting the biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
of Costa Rica. There is a single anecdotal report from the 1970s of a golden toad in the mountains of Guatemala
Guatemala
Guatemala is a country in Central America bordered by Mexico to the north and west, the Pacific Ocean to the southwest, Belize to the northeast, the Caribbean to the east, and Honduras and El Salvador to the southeast...
near the village of Chichicastenango
Chichicastenango
Chichicastenango, also known as Santo Tomás Chichicastenango, is a town in the El Quiché department of Guatemala, known for its traditional K'iche' Maya culture. The Spanish conquistadors gave the town its name from the Nahuatl name used by their soldiers from Tlaxcala: Tzitzicaztenanco, or City...
, but this sighting has not been confirmed. There is also another extinct frog sometimes compared to the golden toad found in the same forest in Costa Rica, named Holdridge's Toad
Holdridge's Toad
Holdridge's Toad was a species of toad endemic to Costa Rica. As of October 2008, it has been declared extinct by the International Union for the Conservation of Nature in its Red List for 2008....
.
Extinction
In the spring of 1987, an American biologist who had come to the cloud forest specifically to study the toads counted fifteen hundred of them in temporary breeding pools. That spring was unusually warm and dry and most of the pools evaporated before the tadpoles in them had time to mature. The following year, only one male was seen at what previously had been the major breeding site. Seven males and two females were seen at a second site a few miles away. The year after, only one male was found. No golden toad has been seen since then. As late as 1994, five years after the last sighting, researchers still hoped that B. periglenes continued to live in underground burrows, as similar toad species have lifespans of up to twelve years. By 2004 IUCN listed the species as extinct, after an evaluation involving Savage (who had first discovered them 38 years earlier). IUCN's extinction was based on the lack of sightings since 1989 and the "extensive search[ing]" that had been done since without result. In August 2010 a search organised by the Amphibian Specialist Group of the International Union for Conservation of Nature set out to look for various species of frogs thought to be extinct in the wild, including the golden toad.Jennifer Neville has examined the different hypotheses explaining the extinction of the golden toad in her article "The Case of the Golden Toad: Weather Patterns Lead to Decline". Neville comes to the conclusion that Crump's El Niño hypothesis is "clearly support[ed]" by the available data. IUCN gives numerous possible reasons in its description of the past threats to the species, including "[the golden toad's] restricted range, global warming
Global warming
Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...
, chytridiomycosis
Chytridiomycosis
Chytridiomycosis is an infectious disease of amphibians, caused by the chytrid Batrachochytrium dendrobatidis, a non-hyphal zoosporic fungus. Chytridiomycosis has been linked to dramatic population declines or even extinctions of amphibian species in western North America, Central America, South...
and airborne pollution
Air pollution
Air pollution is the introduction of chemicals, particulate matter, or biological materials that cause harm or discomfort to humans or other living organisms, or cause damage to the natural environment or built environment, into the atmosphere....
". Neville also mentions arguments that an increase in UV-B radiation, fungus
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
or parasites
Parasitism
Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...
, or lowered pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
levels contributed to the Golden Toad's extirpation.
A more recent study confirms the El Niño hypothesis, in which it is stated that "The new study finds that Monteverde was the driest it’s been in a hundred years following the 1986-1987 El Niño, but that those dry conditions were still within the range of normal climate variability". The new study has shown that the Chytrid Fungus
Batrachochytrium dendrobatidis
Batrachochytrium dendrobatidis is a chytrid fungus that causes the disease chytridiomycosis. In the decade after it was first discovered in amphibians in 1998, the disease devastated amphibian populations around the world, in a global decline towards multiple extinctions, part of the Holocene...
has spread due to the dry conditions caused by El Niño.
Further reading
- Field Notes from a Catastrophe - Elizabeth Kolbert
External links
- 'The Extinction of the Golden Toad - Symptom of a Worldwide Crisis' at Miami UniversityMiami UniversityMiami University is a coeducational public research university located in Oxford, Ohio, United States. Founded in 1809, it is the 10th oldest public university in the United States and the second oldest university in Ohio, founded four years after Ohio University. In its 2012 edition, U.S...
- Arkive: Golden Toad - Bufo periglenes
- Mongobay: Golden Toad
Media
- Bufo periglenes at CalPhotos