The frogs, snuggly swaddled in damp moss in vented plastic deli containers big enough for a small fruit salad, were perhaps the last of their kind, collected from a pristine national park that fills the bowl of El Valle, an inactive volcano in Panama.

In many parts of the world, habitat loss is thought to be the biggest driver of amphibian extinctions, but the frogs in El Valle are facing a more insidious threat.  A waterborne form of chytrid fungus is marching down the spine of the mountain range where they live. Scientists aren't exactly sure how the fungus, Batrachochytrium dendrobatidis, kills, but it seems to break down a protein in the skin called keratin that may be important for respiration. The skin of infected animals sloughs off in layers, and within two weeks, they die. The chytrid fungus is thought to play a large role in the worldwide disappearance of amphibians, a trend terrifying to experts, who say it would be the first loss of an entire taxonomic class since the dinosaurs.  

Joseph R. Mendelson, curator of herpetology at Zoo Atlanta, who has discovered some 50 new species of frogs only to watch half of them become extinct in the last 15 years because of the fungus, was tired of watching helplessly as salamanders, newts and frogs were eradicated from one patch of forest after another.  With the help of new data published on Feb. 28 in The Proceedings of the National Academy of Sciences by Karen R. Lips, a zoologist at Southern Illinois University who spent years tracking the chytrid fungus, scientists were able to predict where it would next strike.  "When you can make predictions with respect to catastrophic population declines and extinctions, we all agreed you have a moral and ethical responsibility to do something about it," Dr. Mendelson said.

Dr. Lips called Dr. Mendelson and Ron Gagliardo, the amphibian conservation coordinator at the Atlanta Botanical Garden, because the men have a reputation for being especially good at catching and taking care of frogs, and proposed an idea that would seem reckless to most biologists.  She wanted them to collect as many frogs of as many different species as they could and move them out of El Valle as soon as possible. She estimated they had only weeks to carry out the mass frog evacuation.  "We are going to over-collect hundreds of animals," Dr. Mendelson said. "That flies in the face of all conservation logic."  There was no time to do the meticulous studies of behavior, reproduction, eating habits and habitat that zoologists try to conduct before moving any endangered species from its natural environment.  There was not even time to figure out where to keep hundreds of frogs.  "Years and years of work go into moving one species out of the environment," Dr. Mendelson said. "We decided that can't happen. There's no time for that. We had to figure out what could be done quickly and, of course, legally."

They went into the forest at night, since most frogs are nocturnal, slogging down a river in hip waders and carrying powerful flashlights. After four separate trips, some lasting only 48 hours, the two men, along with a native guide who possessed stealth and fast hands, managed to gather 600 frogs, shooting for 20 males and 20 females of each species to ensure good genetic variation in their breeding colonies.  To feed them, they rented a house and left piles of rotting fruit in the corners to attract flies. "It was pretty stinky," Mr. Gagliardo said. 

Then there were those trips through airport security.  A guard in the Panama City airport was not satisfied with the letters of explanation the biologists presented, even though they included permission from the Panamanian government to collect the frogs.  He had them open a container that held the Michael Jordan of jumpers, a species the biologists liked to call rocket frogs.  

"I open it and, sure enough, the frog goes bing!" Dr. Mendelson said.  Fortunately, Mr. Gagliardo caught it before it landed on anyone in the amazed crowd that had gathered.  Many of the species they brought home to their respective institutions in Atlanta have never before been kept in captivity.  But Mr. Gagliardo, who has been bringing frogs home since he was 4 years old, has developed a fine touch for their husbandry and for recreating environments for them to thrive and breed.  He quickly realized, for example, that a translucent species of frog collected from a cloud forest wasn't breeding because it needed, well, clouds.  With a cool-misting humidifier he bought on eBay and some plastic pipe, Mr. Gagliardo filled the glass frogs' tank with a steady whisper of white water vapor. Once the tank, which sits in a corner of a behind-the-scenes room at Zoo Atlanta, was bubbling over with a creeping mist like a witch's caldron, tadpoles followed in short order.

"It's a bit of a Noah's Ark, in some ways," Mr. Gagliardo said. "But it gives these species that are predicted to go a new lien on life."  Not all experts, it should be noted, are fans of what has come to be called the rapid response protocol.  Dr. David Wake, an integrative biologist at the University of California, Berkeley, said the strategy felt too much like triage.  "I am alarmed at the apparent disappearance of so many amphibians in Central America," Dr. Wake said. "But if the situation is so bad then much organized thought should be given to a plan for captive breeding that is not responsive to emergencies only, but that looks at all amphibians worldwide to decide where limited funds would be best spent."  Not all species are equally valuable, he noted, and not all are equally at risk.

Still, in an apparent validation of their tactics, Dr. Mendelson said the chytrid fungus had recently been found in El Valle, as predicted, and he estimated 90 percent of the frogs there would be gone within 90 days.  "You won't hear scientists say this too often," Dr. Mendelson said. "But I wish we were wrong."