When it comes to finding frogs in the forests of Vietnam, timing really matters.
In 2007, my colleagues and I found two, strange looking Asian Leaf Litter Toads (genus Leptolalax) in the forests of Quang Nam Province, in Central Vietnam. Both were females, and they were larger and paler in colour compared to the other species of Asian Leaf Litter Toads at the same site. In fact, they appeared to be an undescribed species (which was later confirmed using morpholgical, molecular and bioacoustic data). Both frogs I'd encountered simply by chance, as they weren't by the streams that we most frequently survey. Instead, they were sitting on vegetation far away from the streams.
In 2009, in neighbouring Kon Tum Province, we found three more of these strange frogs, sitting in the forest away from the streams, and again, all three were female. We couldn't hear the species calling anywhere. We were now well and truly intrigued. Where were all the males? When did this species breed? And was this species truly as rare as it seemed?
In 2010, our questions were answered. As soon as the sun set on our first night back in the forests of Kon Tum Province, a loud chirping began. It seemed like every couple of metres, a tiny frog was chirping insistently. We had never heard the call before. When we saw the culprit, we knew instantly that it was the elusive male of the Asian Leaf Litter Toad we had been in search of. And there were literally hundreds of them!
Our experience with this little frog highlights one of the things that makes finding frog species (and determining their conservation status) tricky. Just because you don't find a frog species when you survey, it doesn't mean it's not there. Similarly, just because you've only ever seen a handful of frogs over several years, it doesn't mean that the frog is rare.
Some frog species live in the rainforest canopy, and will only come down where we can see them during the first few nights of spring rain. Others bury underground and only emerge under the right conditions. Still others, such as Asian Leaf Litter Toads, may stay hidden under leaf litter on the forest floor for most of the year, only to emerge in their hundreds for a couple of weeks a year. Findings frogs has a lot to do with timing- you really have to be in the right place at the right time!
This particular Asian Leaf Litter Toad was recently described by my colleagues and I as Firth's Asian Leaf Litter Toad (Leptolalax firthi). We were finally there at the right place and the right time!
Rowley, J. J. L., Hoang D. H., Dau Q. V., Le T. T. D., & Cao T. T. (2012). A new species of Leptolalax (Anura: Megophryidae) from central Vietnam. Zootaxa 3321: 56–68.
You can read more about amphibian research and conservation in Southeast Asia here.