The call it the rainy season for a reason…

 

In case you’ve never been to the tropics, there are essentially two season here per year. In Panama, this works out as “the dry season” which lasts from about December to April, and “the rainy season” which lasts from May/June to November.  These are rough borders of course and it fluctuates from year to year. Back in 2012, I published a paper which looked at variation in rainfall in Gamboa over the past 40 years or so.  On average, it rains 2.1 meters per year (a little under 7 feet), and the vast majority of it (77%) falls between May and November.

Last year by all accounts, was a horribly dry year due to very strong El Niño conditions. It was great for biologists interested in the effects of drought on trees or other organisms, but everyone that was down here trying to study frogs was in trouble.  Frogs are generally cued by rainfall to come out and breed, so whether you are studying eggs or adults, it didn’t matter: there were just hardly any animals out at all.

So what is this year like so far?  RAINY!  It has essentially been raining every single day.  Every afternoon, sometimes in the morning, even occasionally in the evening. Rain, rain, rain.  This has been great for research, because it means that every night the frogs are extremely active. Yay rain!

For those of you that have never made it to the tropics, it might be difficult to envision what 7 feet of rain in a year looks like. Below are some examples of what happens during a good, but not unusually large, rainstorm.

 

Episode 2

We are approaching the end of our third week in Gamboa, and while in some ways it feels like we have been here forever, it also feels like the plane just landed yesterday. The main excitement of the week has been being able to start running our experimental trials! We have been going to a series of ponds at about 9:30 at night and wading into the water to look for adult frogs. Really, we are just looking for females, because between their vocalizations and their numbers, the males are no problem to catch. The ladies on the other hand, are pretty elusive, which is impressive given that full of eggs, they are about double the size of the males. The first night we went into the field, we looked until just about midnight, and only found two pairs, already in amplexus (paired for mating), at the very end. Since then, it has become significantly easier to find them (partly thanks to the rainstorms), and we’ve been able to find six pairs a night in under an hour.

ebraccatus male calling

When the pairs are caught, we place them in the artificial ponds and cages we constructed. We then return at 6am the following morning to re-capture them and to painstakingly count each and every egg. Just to refresh, we are interested in looking at the choices that the females make about laying eggs in the water or on plant matter right above it. These decisions are usually prompted by cues from predators in the water, or the risk of eggs drying out in un-shaded areas. Still, some females are much more predisposed to make one choice over the other, even when it is counteracted by the environmental cues. Because of this, we spend a couple hours at sunrise counting every egg (there are usually 200-300 in a clutch!), making sure to note exactly which are laid in the water, and which are only exposed to air. This gets a little trickier because many of the clutches are placed along plant matter that spans from underwater up over the surface. The eggs are then brought into the lab, where we take care of them until they have hatched and developed long enough to begin our tadpole behavior trials.

Egg-counting

On one of our recent days off, Annie, Hubert and I all hiked up to the Resort’s canopy tower. Now, Annie and I figured that since it was a resort attraction, the hiking couldn’t be that hard… Well that wasn’t true. This is mostly because the resort guests don’t actually hike this trail, they take the more expensive, probably beautiful, dare I say lazy gondola that delivers them right to the base of the tower. Instead, we took some very old and ridiculously steep stairs, walked a little bit, and then took a whole second staircase. I’m pretty sure that they forgot to put in a stair every once and a while, and the distance between the steps would go almost up to my hips. It was all worth it once we got to the top, the canal from up that high was beautiful. We didn’t see a sloth, which was pretty disappointing, but a toucan was waiting for us at the tops of the trees instead, which was amazing. Back at the bottom, Hubert climbed a palm tree, and the coconut water was much appreciated!

So Many Stairs!  Canopy Tower

Canal  Tower

We also got the opportunity to spend a day in Casco Viejo, the Historic District of Panama. We spent most of the day walking along the Cinta Costera, a pathway along the shore, which led us from the old, scenic area of Casco to the modern skyscrapers of Panama City.

Panama City Frog statue

We stopped for ice cream, as well as tapas, and were able to get a great view of the whole city from the rooftop bar at the restaurant. We barely made a dent in the list of suggested places that Justin gave us, and I know we are all eager for an opportunity to go back and explore some more!

Casco1  Rooftop

 

Week One

We are spending the next two months studying reproductive plasticity in Dendropsophus ebraccatus (also known as the hourglass tree frog or the pant-less tree frog!). These frogs show an unusual tendency to lay eggs both in the water and terrestrially, which has some interesting implications for understanding the evolution of eggs that don’t depend on being in water to survive. We are placing breeding pairs in controlled field cages, and trying to isolate females who really prefer to lay their eggs in water, or prefer not to. We will keep the frogs in captivity here, and breed them again, to make sure we are finding the extremes. These lucky frogs get a plane ticket back to New York with us at the end of July to form a breeding colony at Vassar. Through longer term artificial selection we are hoping to be able to try to find the genetic basis for this phenotypic variation. Phoebe will also be building her senior thesis at Vassar off of this project by testing ebraccatus tadpoles raised with different predators  for behavioral variation, and then setting them up in a choice test with each predator to determine how, if at all, this variation affects their survival.
DSCN0352

A male Dendropsophus ebraccatus calling in attempt to attract a female.

We spent a lot of time this week making trips to the hardware store for materials, and then constructing the cages. All of our cages and general materials are made out of storage boxes, window screen, dog pools and all kinds of crazy stuff. We built shelves in the lab out of long planks of wood and cinder blocks. We also collected grasses and floating plants to go in our artificial ponds.
2016-06-06 17.35.11

Phoebe and Annie with one of the six cages we built.

IMG_0565

Hubert after digging up soil for our plants.

On Tuesday, we caught our first two pairs of frogs for the experiment. Although we’ve been searching out D. ebraccatus, we have also been having a blast learning all the different frog calls and tracing them back to the frogs, our tally is over 10 species as of right now! We have also had a lot of fun with every new species, and have found some pretty crazy spiders, insects, lizards, and snakes.
DSCN0020

Annie holding a cat-eyed snake.

DSCN0310

Phoebe with a red eyed tree frog (Genus: Agalychnis)

DSCN0052

Hubert with a basilisk lizard, which has the ability to run on the water’s surface.

Although most of our time has been spent with the frogs, we have had some time off to explore the area. We’ve hiked some of the local trails, cooled down at the pool at the Rainforest resort, and visited the animals at the the Summit Zoo. We’ve also gotten the opportunity to attend several talks about different subjects in tropical ecology. 

 

IMG_0118

A Harpy Eagle at the Summit Zoo

IMG_0097

View of the pool at the Gamboa Rainforest Resort

After spending much of this week on set up, the experiment is in full swing! We will spend the next few weeks catching more ebraccatus pairs for our mating trials, as well as beginning the tadpole experiments. More updates to come!

Off to Panama!

airport

From left to right: Annie Innes-Gold, Phoebe Reuben, Hubert Szczygiel and Justin Touchon prepare to board United 1021 to Panama City, Panama.

It’s June 1st, 2016 and here we go!  Two months of research in Panama await the four of us.  Hopefully it will be productive, instructional, fun, and amazing.

Getting here has been challenge, both in the short- and long-term.  It has taken months of permit applications and research proposals to get to where we can actually go to the Smithsonian Tropical Research Institute (STRI) to do our work.  Then the whole start of the trip was almost derailed when I left my passport at home!  Luckily I realized that before we were out of Poughkeepsie and we ended up making it to the Newark airport with plenty of time for our flight.  Off we go!!