A forest less than half the size of Manhattan sports an astounding number of frogs, according to a new paper in Biodiversity Conservation. Two surveys of Madagascar’s Betampona Nature Reserve, which covers 2,228 hectares, has uncovered 76 unique frogs, 36 of which may be new to science. To put this in perspective: the U.S. and Canada combined contain just 88 frog species, but cover an area nearly a million times larger than Betampona.
Lead author of the paper, GonÃ§alo M. Rosa, told mongabay.com that the reason why this forest held so many frog species “is still a mystery.” He notes that up to 24 of the species in the forest may be endemic, i.e. found no-where else in the world but in tiny Betampona.
“And that’s why these numbers are so extraordinary (especially compared with other tropical forests),” Rosa exclaims. “Betampona is also considered a botanical ‘hotspot’ with 20 of the 100 most endangered Malagasy plants found within its borders!”
Rosa and colleagues are currently examining the potentially new frogs from all angles to determine which ones are in fact new to science, including studying the frogs’ morphology, calls, and genetics. He says such an approach is “essential nowadays to sort out the real status of a species claimed to be ‘new’ based only on one aspect.”
Found on the eastern coast of Madagascar, Betampona conserves one of the last surviving lowland forests in the country. The forest fragment is so small that it could fit over five times into the Walt Disney World Resort in Florida. Yet Madagascar’s dwindling forest land continues to be under assault by widespread slash-and-burn agriculture, overexploitation, logging and bushmeat hunting, all fueled by widespread poverty, poor governance, and overpopulation. Not just home to frogs, Betampona also harbors eleven lemur species, including the Critically Endangered black-and-white ruffed lemur (Varecia variegata). In addition, a recent study in mongabay.com’s open access journal Tropical Conservation Science found that Betampona had one of the world’s richest semblance of tree and shrub species with researchers cataloguing 244 species in less than one hectare.
But, says Rosa, this biological jewel, less than half the size of Manhattan, is not fully secure.
“Betampona now represents a rainforest island surrounded by degraded areas. The conservation issues facing Betampona are similar to those already quoted for many other forests and massifs such as illegal logging or bushmeat: although we consider the Betampona amphibian fauna to be at risk because of the small size of the reserve and of its isolation from other forests and other amphibian populations. This could lead to a general impoverishment of the amphibian fauna living there, such as observed in other fragmented forests.”
Rosa also notes that an alien plant species, guava (Psidium guajava), is providing a new challenge for the reserve. Still, there is hope for the frogs, says Rosa, who calls the reserve “one of the best-managed protected areas in Madagascar.”
“Betampona reserve is currently under the management of Madagascar Fauna Group and Madagascar National Parks. The high level of training of the guides working at Betampona has allowed an incredible continued control of the reserve,” he says.
Around 70 percent of Madagascar’s species are endemic to the island. Having been separated from the mainland for tens-of-million of years, Madagascar is a massive biological laboratory where species evolved in long-isolation. The island is now home to all of the world’s lemurs, half of the world’s chameleons including species the size of a fingernail, bizarre tenrecs, and an incredible diversity of frogs, among other wonders.