Skip to content

Saving the world's frogs, one ark at a time


The Kihansi Spray Toad is nearly extinct in its native Tanzania but survives at the Bronx Zoo in New York City. (Photo by Julie Larsen Maher/WCS)


The Wyoming Toad is extinct in the wild but can be seen in captivity at the St. Louis Zoo and Cheyenne Mountain Zoo among others. (Photo by Chuck Dresner)

Mimic Poison Frog

The Mimic Poison Dart Frog can be seen at the National Zoo in Washington, D.C. (Photo by Joe Milmoe)

Abah River Flying Frog

The Abah River Flying Frog of Indonesia is threatened by habitat destruction. (Photo by Norhayati Ahmad)

Spotted Tree Frog

A Spotted Tree Frog being tested for chytrid fungus. (Photo by Michael McFadden)

Lemur Leaf Frog

The Lemur Leaf Frog is endangered in Central America but some live at the Atlanta Botanical Garden. (Photo by Ron Holt)

Cacao Robber Frog

The Cacao Robber Frog is endangered and can only be found in one tiny area of the Columbian cloud forests. (Photo by Miravilis Swarovsky)

When David Green began his career as an amphibian biologist in 1977, he found an abundance of frogs, salamanders, larvae and tadpoles to study in California. Within a few years, however, he noticed something alarming.

“I was out looking for populations to do my work in places where there were records of a high number of frogs and I couldn’t find any," said Green, who now teaches evolutionary genetics and conservation biology at McGill University in Montreal. "And I’m pretty good at finding frogs.”

It wasn’t until 1989, when herpetologists from around the globe convened for a conference in Canterbury, England, that the scale of the problem became clear. As Green and other biologists exchanged information, they realized something was terribly wrong: frogs were disappearing.

“These highly visible, highly abundant animals in all parts of the world were no longer highly abundant or highly visible,” said Green.

Indeed, since the 1980s dozens of species of frogs have vanished. In Costa Rica, the Golden Toad–known for the males’ electric neon-orange coloring–is nowhere to be found. In the United States, the chubby, brown Wyoming Toad no longer exists in the wild. In Australia, the googly-eyed Northern Gastric-Brooding Frog has not been found despite extensive searches since 1985.

According to the Global Amphibian Assessment report, published in 2006 by the International Union for Conservation of Nature, as many as 165 species may already be extinct and nearly half of the remaining 6,000 species are at risk of extinction soon. The report classified more than 400 species of amphibians as critically endangered.

“What we’re seeing is the largest extinction event since the dinosaurs,” said Shelly Grow, a conservation biologist with the Association of Zoos and Aquariums in Silver Spring, Minnesota.

Frogs, toads, newts, salamanders and caecilians (which are worm-like, underground dwelling creatures) are all amphibians. They play critical roles in their respective ecosystems and food chains, provide valuable medicines for humans and serve as crucial barometers of environmental health.

Habitat loss, pollution and climate change have all contributed to declining amphibian populations, but the newest threat is a mysterious disease called Batrachochytrium dendrobatidis or “chytrid” fungus. First discovered in 1999 in Panama and Australia, the fungus causes amphibians’ porous skin to harden and can decimate local frog populations within months.

The fungus’s threat to amphibian species all over the world has grown so severe that an initiative called Amphibian Ark–representing dozens of international conservation groups, national organizations and regional zoos, botanical gardens and aquariums–was launched last year to help bring endangered frogs in from the wild and place them into modern-day “arks.”

Amphibian Ark’s goal is to quarantine 500 endangered species of frogs in biologically secure environments until a solution to their demise is found. The group, run by a small team of biologists from around the globe, has declared 2008 the “Year of the Frog” and is helping with education campaigns, fundraising and outreach in zoos and aquariums around the world.

One problem is coming up with additional space to house the rescued frogs.

“The global conservation community has 10 percent of the capacity it needs to bring these species in from the wild,” said Kevin Zippel, program director of Amphibian Ark. “That’s only 50 species out of 500. If we can collectively raise $50 million this year, that breaks down to $100,000 to save each species. It’s pretty good value, if you ask me.”

In North America, where chytrid fungus has been found in 20 states, many zoos are creating special exhibits to educate children and adults about frog extinction and conservation.

“The best message people can take home is that the frog is a global canary,” said Dave Collins, curator of forests at the Tennessee Aquarium in Chattanooga, referring to the tradition of coal miners carrying canaries down mine shafts to detect poisons in the air. “It’s a cliché, but this is a situation where an entire class of animals is on the brink of a major catastrophe. It’s a huge wake up call that we are not being very good stewards of our environment.”

He hopes people who see the Tennessee Aquarium’s own frog exhibit will become more aware of what they can do in their own backyards to help the frog crisis. “Should we spray pesticides on our lawn? Do we want green grass or do we want an environment rich in animal species?” he said.

At the Detroit Zoo, zookeepers host “Hoppy Hours” year-round, when visitors can drink cocktails and socialize at the amphibian exhibits. The zoo is also trying to acquire another endangered frog species to keep at the National Amphibian Conservation Center, which already has 65 amphibian species, according to Scott Carter, director of conservation and animal welfare.

New York’s Bronx Zoo has updated an exhibit on the plight of the Kihansi Spray Toad in its Reptile House. Since 2001, the zoo has housed a small “assurance colony” of the tiny, yellow toads, which face certain extinction from habitat destruction and chytrid fungus in their native Tanzania. Later this year, scientists from Tanzania’s University of Dar es Salaam will visit the Bronx Zoo to learn how to breed the toads back in their homeland.

Not all biologists believe that taking frogs out of the wild and placing them into arks is the best approach. “It may be that the individuals that get through the disease in the wild are the future of the species,” said one biologist who did not want to be named, because his views go against the mainstream. “If you take them into the zoo, you cut that off.”

But many biologists say that chytrid fungus is so disastrous that options for conservation are extremely limited. "We don’t know how it spreads, why it spreads and we certainly don’t know how to cure it,” said Green in Montreal. “The only thing to do until we figure it out is take the species into captivity and keep them safe."

If the Amphibian Ark initiative is successful but other conservation strategies are not, the project would have failed, said Zippel, the group’s program director. “We have to fix the threats in the wild and safeguard their habitat or we won’t have anywhere to return these species to,” he said. “We’re the first ones to admit this is the last ditch solution.”