A Silence in the Forest

We are all familiar with the steady undulating drones we hear as night approaches during the warming months of the year. For many of us, those sounds are synonymous with childhood memories; chasing fireflies in the back yard, running through the woods, sitting on the back porch, fishing and camping. Most believe that the clamor came from insects, but when we observe closely, we find that many of those sounds come from frogs. These sounds, the signal that night is impending, come from invisible gray and green tree frogs, rowdy bull frogs, the audacious gulf coast toad, the love sick leopard frog, and many other varieties. We hear these sounds nearly every day, and sometimes we may take them for granted. Imagine that your backyard, all at once… became silent. In some parts of the world this has happened. An eerie silence has taken hold in places once swarming with a chorus of raucous frog calls.

There are approximately 6000 species of amphibians living on our planet today. Alarmingly, about a third of them are in real danger of extinction and almost half of them are in real trouble. Scientists liken the current crisis to be on par with that of the mass extinction that brought about the demise of the dinosaurs. What’s even more astounding is that it is happening as quickly as a blink of an eye. Some of the dangers amphibians face are from habitat loss and pollution, but the newest villain is a fungus. Commonly called the Chytrid (kitch-rid) fungus, it has wreaked havoc across the globe. Initially thought to have originated in South Africa, this fungus was spread globally through the commercial trade of the African clawed frog. The fungus attacks the frog's skin. Since frogs use their skin in respiration, it becomes difficult for the frog to breathe. The fungus also damages the nervous system, affecting the frog's behavior. This fungus can be devastating to populations of frogs. The fungus has been discovered on every continent that has frogs. It has been observed to spread as much as 62 miles per year. Where it exists, 50 percent of the species and 80 percent of the individual animals that are exposed to the fungus can be expected to disappear. There are 500 species that are in such trouble that biologists believe the threat cannot be diminished in time to stave off extinction. Because of this, zoos and aquariums throughout the world have been recruited and are rushing to assist in this plight.

2008 has been deemed the “Year of the Frog” by many conservation organizations including the Association of Zoos and Aquariums (AZA). The AZA has been spreading the word that these diminutive, often overlooked species are in peril. The San Antonio Zoo is doing its part as well. The opening of TOADally, a series of exhibits dedicated to amphibians, will allow Zoo guests an up close view of some of these highly endangered species, and some not so endangered. The educational message the exhibit sends is not only about the Chytrid fungus but how everyone can make a difference in their own backyard. Our Zoo Team volunteers are participating in the National Wildlife Foundation’s “Frog Watch” program to help monitor toad and frog populations. The Zoo’s reptile and amphibian curator, Alan Kardon, in collaboration with other institutions, has traveled to Mexico to test frogs in the wild for evidence that the fungus is present. Also, the San Antonio Zoo has set up a preserve-like exhibit inside the new Africa Live! building. Away from other amphibians and most people, the Zoo focuses its efforts to help save one species in particular, the Puerto Rican crested toad. This is the only toad native to Puerto Rico. Toad numbers have declined dramatically, due to habitat loss and introduced species. The amphibian staff established about a dozen tanks in which the toads are housed and will hopefully propagate. The tanks are kept in relative isolation in hopes of establishing something of a quarantine zone to prevent any disease transmission to these very rare animals. There currently exists a national plan to reintroduce these toads to their native homes. With a little luck, we will be able to assist the plan and provide offspring to help bolster the wild population.

The Zoo has made a commitment to amphibian populations by assisting to preserve this very rare species and others so that we may continue to hear those melodic nighttime sounds once the weather starts to warm.