Treefrogs in Thailand: Film Teaser

** The following is a guest post from Wild Lens biologist and filmmaker Adair McNear who spent the summer and fall of 2012 in Thailand studying an endemic species of treefrog. She is currently editing a short film about the project and offers up a teaser on what she has been working on. **

I wanted to share some of the footage collected from our study site and show a bit of the frogs and general biodiversity of the research station (click on the video below to play):

Sakaerat Environmental Research Station (SERS) is a great research base for scientists, both Thai and foreign, with lab space, friendly staff, luxury field amenities (a hot water shower!), and ample, beautiful secondary growth forest. The research station functions mainly as a day and overnight camp for school groups from all over Thailand, ranging in age from about 6 to 18, and sometimes hosting undergraduate and graduate college students. For kids from major metropolitan areas like Bangkok or the nearby city of Korat, this might be their first time in the “wild,” and by the looks of the big smiles on their faces as they get up just after dawn to go birding, or catch a glimpse of our field team braving the pond water in search of frogs as the sun sets, they love the experience.

Our study site consisted of two freshwater ponds; the smaller pond (shown first, in daylight) just steps away from our field house, and the larger pond about 2km away (shown in the timelapse shot). The incredibly large stick insect (a whooping 26cm) was a resident of a tree on the bank of the smaller pond. The Little Spiderhunter, a member of an Old World group of nectar-eating birds similar but unrelated to hummingbirds, would feed daily on the flowers of the banana plant just outside our field house. There were multiple late mornings that his loud, territorial chirps would wake me up, which is not so charming when you’re trying to catch some sleep after having been awake since 2 am and working in the ponds.

Chiromantis hansenae. Photo by Adair McNear.

I included some clips of male Chiromantis hansanae calling at night. Their high-pitched, single-note “chirp” is barely audible against the cacophony of other frog species and insects calling along the pond’s edges. However, as we spent more time with the frogs we were able to distinguish each species’ call, and just like the female Chiromantis frogs (who do not vocalize) we could tell just by listening if the right crowd was hanging down at the pond on a given night.

The shot of one frog on top of another is a mating pair of Chiromantis in the amplexus posture, where the male is atop the slightly larger female. He will remain with her for hours, sometimes lightly bobbing his head, until the female has selected a suitable leaf or twig to lay her clutchon, which is then externally fertilized by the male. The last frog shown is a female just after she has laid her clutch. The male has already fertilized the egg clutch and has left, while the female is kicking over the mass of eggs with her hind legs in order to hydrate them and also to create a layer of foam and will form a layer of gel over the eggs, protecting them from the elements and aiding in their continued hydration.

- Adair McNear


Filming Incubating Treefrogs: An Update from Thailand

 

** This is the second field update from Adair McNear.  Adair is studying and filming the reproductive behavior of an endemic treefrog, Chiromantis hansanae, in Thailand as part of Sinlan Poo’s PhD research at the University of SIngapore **

 

Chiromantis hansenae female and her eggs. Photo by Adair McNear.

August 10th, 2012:  We’ve been having a dry spell so the frogs’ activity has dropped, although the past few days have been wetter, so breeding should pick up again soon.  In the meantime I thought I’d share how we’re collecting data on the frogs – and incidentally, collecting awesome video of the frogs’ behavior – because it’s a pretty cool method!  When we locate a newly laid clutch of eggs, we set up a timelapse camera on a tripod that runs 24 hours a day (at night we switch on a low intensity light, just enough so we can see if the female is still present).

 

Time lapse camera "watching" a clutch of treefrog eggs. Photo by Adair McNear.

With this continuous surveillance, we end up with 4 or 5 days-worth of footage to then analyze.  It takes about 5 days for the eggs to mature into tadpoles, which then drop into the water and hatch.  The female is present and sitting on her clutch about 80% of this time, which understandably is mostly her remaining still, and not too fun to film in real time.  However, with the timelapse footage, we’ve been seeing condensed views of the females attending to their clutches.  These have included predation attempts from ants and carnivorous katydids, with one female managing to fight off a katydid twice her own size!  Another female had to scare off a male Chiromantis hansanae who was fruitlessly attempting to mate with her (the females are not receptive when they are guarding their clutches).  I’ve attached some photos of one of the timelapse cameras set up in the field, and a couple of cropped screenshots that it has captured.  ~  Adair McNear

 

Chiromantis hansenae female leaping away from her eggs. Screenshot by Adair McNear.

Chiromantis hansenae stands guard over her eggs at night. Screenshot by Adair McNear.

 

 


Treefrogs in Thailand: Part 1

 

Amphibians may be the worlds most threatened taxonomic group with an estimated 30% of worldwide populations being threatened, and over 40% experiencing population declines.  These numbers, coupled with an extinction rate over 200 times the normal-background extinction rate, are leaving researchers all over the world grasping for answers to the causes of these mass declines and extinctions.  Some proposed causes include habitat loss, disease, pesticide use, pollution, and increased ultraviolet radiation.

 

Chiromantis hansenae mating. Photo by Adair McNear.

Wild Lens biologist-filmmaker Adair McNear is currently working with University of Singapore PhD student Sinlan Poo at Thailand’s Sakaerat Research Station studying the reproductive ecology of an endemic treefrog, Chiromantis hansenae.  This treefrog’s reproductive cycle is closely tied with the start of the monsoon season, and one of Sinlan’s research goals is to gain a better understanding of how global climate fluctuations may impact this little-studied species in the face of worldwide population declines.  The following is a brief report from Adair on how the start of breeding season is progressing.

 

Chiromantis hansenae female laying eggs. Photo by Adair McNear.

“The wet season is a little slow in coming, so while the frogs are indeed breeding (rains are intermittent, so it’s not a drought situation), its not the peak of breeding season yet, and chances to film the frogs in the study site are still pretty unpredictable. However things should pick up a lot once we start getting more storms, so for the time being I’ve been trying to get some general monsoon/predator “b-roll” and will work on getting the interview footage with Sheila in the next couple of weeks. There is also a good amount of frogs in aquariums for a controlled subset of Sheila’s research; these frogs will be a lot easier to film but may not have that “natural” look.  ~ Adair McNear”

Chiromantis hansenae. Photo by Adair McNear.

Stay tuned for more detailed updates from Adair as she continues to monitor the breeding progression of these frogs!