Frogs have been around for 250 million years, and despite what we might call their tenacity to thrive from an evolutionary standpoint, they are highly endangered from loss of habitat, pollution and a fungal disease known as chytrid that is spreading from continent to continent like wildfire.Frogs are essential in the web of life – they are voracious insect eaters and a food source for predators higher on the food chain. And researchers know they offer medical benefits to humankind. (Frog poison is already used in surgical procedures.)
In the midst of this tragedy-in-the-making, biologists are still discovering frogs previously unknown to science. In 2011, two so-called “pipsqueak” frogs smaller than a penny, were discovered in Papua New Guinea. Half a world away, a team of biologists has been exploring tepuis, or “islands in the sky” – huge vertical fragments of the 2 billion-year-old rock formation known as the Guiana Shield in Venezuela, Brazil and Guyana – where they have discovered frogs that are endemic to each of the tabletop mountains.
In 1988, I ventured to the tepuis, (pronounced te-poo-eze) during a trip to Canaima National Park (the size of Belgium) and Angel Falls in the southern part of Venezuela. We traveled by dugout canoe down the Carrao River — the water is the color of well-brewed tea and a healthy population of anacondas keeps you from trailing your hand in the water. It’s much too arduous for visitors to get to the scrubland and forested tops of these peaks — often 1,000 meters high with sheer cliffs and waterfalls. It is the lost world described in Hudson’s novel Green Mansions.
Scientific expeditions are usually dropped in by helicopter and then picked up. A study of tepui-based frogs published recently in the journal Evolution compared DNA from four species of tree frogs found on different tabletop mountains. The team concluded: the frogs climbed up there, over a period of millions of years.
Efforts to prevent total species extinctions are underway on several continents. The excellent The Thin Green Line PBS documentary ( Nature episode free online) shows conservation specialists at El Valle Amphibian Conservation Center in Central Panama, sheltering 58 species of frogs, including the rare golden frog, which no longer exists in the wild. The only chytrid-free area left in Panama is the Burbayar Forest, still full of healthy frogs. Meanwhile in Washington State, inmates at four prisons are raising imperiled Oregon spotted frogs (rana pretiosa) from eggs to adults for reintroduction into threatened habitats. The prisoners in the Sustainability in Prisons program work with a state biologist to manage the entire process, from harvesting crickets grown for frog food to maintaining water temperature for the tadpoles.