Mountain hopping for frogs

I’ve been back in northern Vietnam to join a survey for Sterling’s Toothed Toad (Oreolalax sterlingae) and Botsford’s Leaf Litter Frog (Leptobrachella botsfordi), currently Vietnam’s only known Critically Endangered amphibians. Their stronghold is Mount Fansipan (3143 m), the tallest mountain in Indochina and now also a popular tourist destination, with cafes and temples on its summit and a cable car to ferry hundreds of people up the mountain every day. With such rare frogs living so close to development and under pressure from other habitat disturbance, our survey aimed to find new populations and monitor the few we already know of, in order to increase the limited knowledge we have about the frogs and their distribution. This new information ultimately helps to protect the frogs because it identifies where and how best to conserve them.

On our most recent survey, we took the old-fashioned route up the mountain- hiking to the top, instead of hitching a ride on the cable car. Along the way, we stopped to search for our two target species, as well as other frog species. Our first stop was at 2200 m elevation. This area was the site of our first camp, and the forest and stream has been heavily disturbed by human activity and fires. Despite this disturbance, we found many frogs here, displaying a stunning array of body shapes and colours, from the familiar looking such as the Green Back Tree Frog (Rhacophorus dorsoviridis), to the aquatically adapted Granular Spiny Frog (Quasipaa verrucospinosa), and the tiny brown Rainy Leaf Litter Frog (Leptobrachella pluvialis)- a close relative of Botsford’s Leaf Litter Frog and also threatened. We heard many more frogs than we saw, with the survey also coinciding with the breeding season of many species.

The next day, when the cloud and cold weather that characterises the region gave way to hot and sunny conditions, we climbed up a whole lot of near vertical steps to reach our second camp, at 2800 m elevation. A short rest and it was time to survey frogs at the nearby stream. Here, we hoped to find the two target species, as we had in the past, but unfortunately, they proved elusive. However, all was not lost- at the very end of the night, we found a species only described by our international team very recently. It was the impressively patterned Mount Fansipan Horned Frog (Megophrys fansipanensis), a species restricted to elevations above 2000 m on Mount Fanispan. Although we found only one individual, finds such as this are a great motivator to continue searching in difficult terrain!

Fortunately, we had a second night at this site, and so after fighting our way through thick bamboo forest we came to a lower section (2600 m) of the same stream we had searched the night before. Looking slowly and methodically through the leaf litter and rock crevices of the stream, this time the team were rewarded with finding both Botsford’s Leaf Litter Frog and Sterling’s Toothed Toad!

The next day, we climbed to the summit and then began our descent down another side of the mountain, where I was encouraged to see a continuous cover of green and mossy forest, in stark contrast to the habitat disturbance we had encountered to reach this point. Here at the final stream of our adventure, we were again lucky enough to locate both of our target species. Finding both species at this site was particularly significant- expanding their known range.

Once we returned from the mountain, we presented our exciting findings at a large stakeholder meeting where we exchanged knowledge and worked on solutions to preserve the unique biodiversity of Mount Fansipan and the rest of the Hoang Lien Range. While the area faces serious threats from habitat clearance for infrastructure construction, stream pollution and other human usage, there is an urgent need to act now to make sure that the many species still existing in the region can persist.

Christopher Portway
Herpetology Research Assistant, AMRI

Acknowledgements

This expedition was part of an Ocean Park Conservation Foundation Hong Kong funded project to understand and protect the amphibians of the Hoang Lien Range, northern Vietnam. The project is a collaboration with the Zoological Society of London, Paignton Zoo, the Asian Turtle Program of Indo Myanmar Conservation and the Center for Rescue and Conservation of Organism (Hoang Lien National Park). Many thanks to all who made this work possible.