Panamanian golden frog facing doom

Denver Zoo breeding efforts key in saving plagued amphibian

Jim Erickson, Rocky Mountain News

Published November 27, 2006 at midnight

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Imagine that all the bald eagles - every last one of them - vanished from the American wilderness overnight.

Something similar is about to happen to Panama's national symbol of nature and wild places: the celebrated Panamanian golden frog.

The brilliant gold-and-black creature, whose image is plastered across everything from T-shirts to lottery tickets in its native land, will soon croak its last croak, biologists say.

Some time next year, the last wild Panamanian golden frogs are expected to die, victims of a lethal skin fungus sweeping southeastward across the Central American isthmus and wiping out entire amphibian communities in its path.

They will become the latest casualties in the staggering, worldwide amphibian decline. The only surviving Panamanian golden frogs will be several hundred captives in about two dozen zoos, including the Denver Zoo.

'Noah's Ark'

"The zoo's role is to be kind of a Noah's Ark," said Thomas Weaver, the Denver Zoo's amphibian keeper and a key player in Project Golden Frog, an international effort to keep the species alive in captivity.

"If we didn't get this animal into captivity, in the future we would have nothing to work with."

The critically endangered Panamanian golden frog is one of the world's best-known and most culturally significant amphibians.

Endemic to the mountain rain forests of central Panama, the frog varies in color from brilliant, egg-yolk gold to pale yellow to greenish-yellow.

It was revered for centuries by indigenous peoples who crafted gold and clay frog talismans called huacas. In modern times, thousands of the frogs were sold to the public at Sunday markets in the town of El Valle de Anton, Panama, according to the Project Golden Frog Web site.

But the creature's numbers have dwindled in recent decades because of deforestation, overcollection and water pollution.

Now the final hammer blow is falling.

Chytrid fungus invades

The relentless chytrid fungus is marching through the heart of the golden frog's homeland. Amphibians breathe and drink through their papery-thin skins, and chytrid fungus suffocates them.

Two years ago the fungus reached the western edge of the Panamanian golden frog's range, advancing at 17 miles a year, said herpetologist Kevin Zippel.

"Pretty much the whole range of the golden frog has now been affected by this disease, and all indications are that (the frogs have) been eliminated wherever the disease went through," said Zippel, lead coordinator of Project Golden Frog.

"So I would say that after this coming dry season, starting in late December, the species will probably be gone in the wild."

So why should anyone, other than a few frog aficionados, care if this 2-inch, cold-blooded insect-muncher gets snuffed?

For starters, because the problem is much, much bigger than the little Panamanian golden frog.

At least 43 percent of the world's 6,000 known species of amphibians - frogs, toads, salamanders and newts - are declining, according to the Global Amphibian Assessment, a 2004 report by 600 scientists in 60 countries.

Habitat loss and degradation are by far the greatest threat.

Thirty-two percent of the world's amphibian species are threatened with extinction, according to the study.

About 120 species have perished since 1980, and the list grows by about 10 species each year, said Zippel, amphibian program officer for the CBSG/WAZA, the Conservation Breeding Specialist Group of the World Conservation Union and the World Association of Zoos and Aquariums.

And the losses are not restricted to faraway rain forests.

Colorado toad affected

The same skin-peeling chytrid fungus that's decimating Panama's frogs is blamed for die-offs among Colorado's only alpine toad, the boreal toad, as well as creatures on several continents.

"Five years ago we were talking about the global amphibian decline," Weaver said from the frog holding room at the Denver Zoo's Tropical Discovery exhibit. "We're now looking at it as a mass extinction. It's considered a global crisis."

In all likelihood, the Panamanian golden frog's precarious future hinges on the success of captive breeding programs under way at a handful of zoos.

So far, just three U.S. institutions - the Denver Zoo, the San Diego Zoo and the National Aquarium in Baltimore - have been able to coax captive-bred Panamanian golden frogs into producing offspring, said Rick Haeffner, curator of reptiles and fishes at the Denver Zoo.

"The challenge is so overwhelming, and the easiest thing would be to do nothing," said Haeffner, a Project Golden Frog coordinator.

"But at least during my watch, I'm not going to let this one frog go extinct," he said.

The trick to successful captive breeding is making the frogs feel right at home, said Watson, who's made four trips to Panama since 2001. In the wild, the frogs breed in swift-moving streams that flow through tropical forests.

Inside a "stream terrarium" at the Denver Zoo's frog room, Watson has replicated that environment in miniature.

The plastic tub is 4 feet long, 2 feet wide and 18 inches deep. Two-thirds of the space recreates a forest floor; the rest resembles a clear mountain stream.

During a recent tour, Watson lifted the terrarium's screened lid, releasing the earthy smell of wet moss and the gurgle of burbling water. Inside, broad-leafed tropical plants, clumps of sheet moss and chunks of cork bark bordered a mini-stream.

The frogs breed in the water.

Gradual insect diet

Once the eggs hatch into tadpoles, they're transferred into other containers and fed algae.

As the creatures mature into mottled dark green-and-black froglets, they're fed increasingly larger live insects: first tiny tropical springtails, then fruit flies, then small crickets.

The froglets, about the size of a pencil eraser at birth, flick minuscule tongues to snag the bugs.

The Denver Zoo currently cares for 19 adult Panamanian golden frogs and has 50-plus froglets that hatched about two months ago.

And what will become of these youngsters? A one-way ticket back to Panama, perhaps?

Not while the chytrid fungus continues to mow down Central America's amphibians.

"There's nowhere to return them to. That's the biggest hurdle," Haeffner said.

Panamanian golden frog

Home range: Central Panamanian rain forests

Status: Critically endangered

Threats: Deforestation, overcollection, water pollution, chytrid fungus

Prognosis: Last wild individual expected to perish in 2007

Size: 2.2 to 2.5 inches for females, 1.6 to 1.9 inches for males

Diet: Insects