The search for the elusive frogs of Mount Fansipan

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Benjamin Tapley is the Curator of Reptiles and Amphibians at ZSL. Ben focuses on the conservation of EDGE species, here he provides an account of our work focusing on bringing the most threatened amphibians in Vietnam back from the brink.

The roof of Indochina

The Hoang Lien Range in in northern Vietnam is dominated by jagged, mist shrouded peaks, powerful waterfalls and swift mountain streams. Hoang Lien National Park and the nearby town of Sa Pa are an increasingly popular tourist destination; the area has a rich cultural heritage, rugged topography and is marketed as “the roof of Indochina”. Many tourists visit the region and spend time trekking through villages perched on the edge of picturesque valleys that are steeply terraced with rice paddies. The more adventurous attempt the ascent of Mount Fansipan, no mean feat, at 3143m this peak is the highest in Vietnam; the less adventurous take the newly opened cable car! As tourists make the ascent up slippery, muddy slopes and cold metal ladders very few will be aware of the fact that the Hoang Lien Range supports an exceptionally rich amphibian fauna which is comprised of over 80 species.

Wide angle landscape photograph looking down a valley with cloud-wreathed mountains in the background
View across the Hoang Lien range

Hatching a plan

In early 2014 I met with Mr. Luong Van Hao, Director of the Centre for Rescue and Conservation of Organism in Hoang Lien National Park. I had recently read two intriguing pieces of research that described two new species of frog; Sterling’s toothed toad (Oreolalax sterlingae) and Botsfords’s leaf-litter frog (Leptobrachella botsfordi). At this time, both species had only been reported from the higher elevations of Mount Fansipan (>2,700 m asl) and there was evidence that these frogs may well be highly threatened. Hao and I quickly hatched out a plan of action, but we needed help. Botsfords’s leaf-litter frog was described by Dr Jodi Rowley, Curator of Herpetology at the Australian Museum and Adjunct Senior Lecturer, University of New South Wales. Jodi was, at that time, one of the only people to have seen Botsford’s leaf-litter frog. Convincing Jodi to accompany me to Mount Fansipan to gather enough data on Sterling’s toothed toad and Botsfords’s leaf-litter frog was much easier than I thought, she agreed but warned me how challenging the field work would be. 

Extremely close-up photograph of a Sterling’s toothed toad
Sterling’s toothed toad

Our objective was to gather enough data to write Red List assessments for these species. This requires a greater understanding of the distribution and ecology of the species, the threats they may face and the extent of available habitat. Red List assessments are extremely important as they are a critical biodiversity indicator for conservation policy and also inform a number of conservation prioritisations schemes such as the EDGE of Existence Programme. Jodi, Hao and I secured funding to do just that. 

The ascent of Mount Fansipan

Before I knew it, we were heading out into the field. We met our team of porters at the base of the mountain, they had rattan baskets piled high with our provisions which included squawking chickens, tofu, dozens of eggs and a great sack of rice; it appeared that many of the porters would be making the strenuous hike in flip flops. The hike begun and within an hour I felt like I was about to cough up a lung. We scrambled over tree roots, traversed windy ridges. After what felt like days, we reached our base for the next three days, a tin shed where tourists sleep overnight before attempting to climb the summit of Mount Fansipan. In my mind I had pictured beautiful mountain vistas and mossy forests reminiscent of Rivendale; instead this site, also the only known site where Sterling’s toothed toad and Botsfords’s leaf-litter frog were known to occur, resembled something out of a post-apocalyptic film. There were low bamboo shelters covered with tarpaulins that were being battered by the wind, and scantily clad shell shocked tourists cowering under the tarps hugging their knees for warmth. 

Photograph of a semi-dried, rocky river bed strewn with rubbish
The survey site

Searching for elusive frogs

We walked from the camp site to the stream and it was clear that this habitat was being severely impacted by the number of people using the site. Large mounds of garbage from the tourist camp had been deposited and people were using the stream as a toilet as well as a source for gravel for path construction. The stream was littered with bottles, toothbrushes and other items that are best left to the imagination. It was clear that the only known habitat of these frogs required protection. That night, and for several nights following we braved biting wind and lashing rain as we searched for frogs. Slightly away from the tourist camp the habitat was more intact and ferns and tiny orchids adorned the rocks lining a beautiful stream, the trees that remained were covered in thick blankets of moss, this was more like it!

Close-up photograph of the Botsfords’s leaf-litter frog clinging to a leaf
Botsfords’s leaf-litter frog

Jodi was the first to spot a frog, she encountered a Botsfords’s leaf-litter frog at exactly the same point where she had found the species in the first place three years previously. It hopped away before I could see it. We patiently waited and a tiny dumpy looking brown frog eventually peeked out from the low thicket of bamboo and despite the fact that our teeth were chattering with the cold we were delighted that the frogs were still there. Further on we found Sterling’s toothed toad; another small brown frog with warty body, long spindly legs and the most incredible black eyes with golden lines radiating out from the iris. Over the next few days we weighed and measured these frogs and took pathogen samples by swabbing the undersides of their stomach and feet. We documented the threats to the frogs and walked a transect down to a lower elevation to determine the elevational range of these frogs. We also found small black tadpoles with golden tail striped in a small pool, we suspected that these were the tadpoles of Sterling’s toothed toads. After several days we had only found the frogs at this single site and returned to the town of Sa Pa with aching limbs, our bodies covered in filth and a strong desire for pizza. 

Assessment and impact

Our hard work paid off, we had gathered enough data to assess the species. Both Botsford’s leaf-litter frog and Sterling’s toothed toad were subsequently assessed as Critically Endangered, they are currently Vietnam’s only Critically Endangered amphibians as their Extent of Occurrence is just 8km2 and their habitat continues to decline in quality. Molecular analysis also confirmed that the tadpoles we encountered were in fact those of Sterling’s toothed toad. 

Group photograph of the six members of the 2015 international team
The international team after the first frog survey in 2015

Our team have been diligently monitoring these frogs every year since and we are very fortunate that Hoang Lien National Park have supported our endeavours throughout. We held a stakeholder workshop to present our findings and launched an action plan for the Amphibians of the Hoang Lien Range which we are now in the process of implementing. The direct impact that tourists are having on this critical site have already been greatly reduced. Once the Red List assessments were published, Botsford’s leaf litter frog was singled out as a high priority EDGE species on account of its global endangerment and unique evolutionary history; this enabled us to seek further funding and upscale our project which is now being championed by our fantastic EDGE Fellow, Luan Thanh Nguyen from Indo-Myanmar Conservation / Asian Turtle Program. Our work has also influenced conservation policy. Mount Fansipan is listed as an Alliance for Zero Extinction site because these Critically Endangered species are present. Moving forward, all Alliance for Zero Extinction sites will become Key Biodiversity Areas and it is really heart-warming to see our work being championed by local partners and that the results are helping to inform wider conservation activities and prioritisation schemes.


Acknowledgments. 

I am extremely grateful to Hoang Lien National Park, in particular the dedicated team at the Centre for Rescue and Conservation of Organism. The Mohamed bin Zayed Species Conservation Fund kindly funded the first phase of research and we upscaled the project with generous funding from The Ocean Park Conservation Foundation, Hong Kong. I am incredibly indebted to Dr Jodi Rowley for her collaboration and friendship as well as laughs when we have both been so tired and exhausted, we could barely stand up. We are also incredibly grateful to Mr. Luong Van Hao for his unwavering support  and collaboration throughout our endeavours. 

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