Poison frogs, deadly bugs, cold showers, Oh how I've changed

We have been at La Selva Biological Station for the past few weeks. La Selva is the most productive biological station in the tropics, and it often feels like an amusement park for researchers. We had the opportunity to work in this research amusement park conducting our own project. We wanted to investigate how warming temperatures might affect strawberry poison dart frogs. To do this we walked around the forest collecting frogs. After we caught dozens of them we brought them back to lab to see if they had a temperature preference and to test their jumping performance at different temperatures. It was only after we had finished our project and written our papers that it really hit me—I had just spent the past week catching poison dart frogs with my bare hands. This was something that I would never have thought to do before I began this program.

I remember back to January being completely freaked out by our lecture on Dangerous and Annoying Creatures of the Tropics. The week following that lecture I would wake up in the middle of the night terrified that there might be a Chagas bug crawling on me. Chagas bugs are in the family Reduviidae, and also known as kissing bugs or assassin bugs. These bugs suck your face while you are sleeping and then defecate on your face. Their poop contains a protozoan, and if this protozoan gets into the open bite then you become infected with Chagas disease, a potentially life-threatening disease. Now I am proud to say that I can sleep through the night, and when I see Chagas bugs I think, “Oh that would be an easy insect to identify. Let me catch it!” I have completely gotten over any fears of outdoor creatures I may have had before this program.

I now see the forest in a completely different way. Remembering back to our first field notebook, I was so bored that I had to stand in one spot for 45 minutes. Looking back at what I had written I realized that I had missed so much—I saw “plants with leaves”, an ant, and a trail. Now when I look at the forest I see so much more—palms in the understory with pinnately compound leaves, large Ficus trees, Oophaga pumilio frogs hopping into bromeliads, Atta ants carrying pieces of leaves many times their size, and I could go on for hours. I have learned to look deeper and better appreciate my surroundings.

This semester has taught me so much and changed how I see the world. I would gladly suffer a million freezing Monteverde showers to do it all again.

Andriana Miljanic

Emory University

Final Exams, Final Projects, Final Thoughts

Things are wrapping up at an incredible rate. It feels like I just got on the plane to start an adventurous semester abroad in Costa Rica yet I’m finishing up my second independent project and done with finals. What’s even crazier is that 4 months ago I didn’t know anything about the tropics. I’ve personally learned more over the course of this semester than I could in a year at my normal college. There’s just no way to replicate the hands on experience we gain through this program.

Today we just finished writing up our Faculty Led Project papers. I worked with Kali under one of our guest professors, Michelle. Our project was to lead our classmates on two days of anole catching and sampling in the forest. We measured different dimensions of their bodies to see if they were able to adjust their morphologies based on what type of forest they were living in. We found that in one of the species they actually do adjust their leg length for the average perch diameter available to them.

Neither of us really understood how cool this was until we saw Michelle’s reaction as we ran the statistical tests together. She said that the results made her feel like she might want to go back and analyze some data she had collected in her own research, but hadn’t considered using yet. This is another great example of the quality of experience we get here. There’s no way I would be able to get this kind of experience at my college in the states.

It’s so important for us to obtain results like this and see how the can apply in the real world. It’s even more important to meet people like Michelle who are actively conducting research and answering real questions about the natural world. These kinds of interactions are what motivate me to stay interested in this field. Seeing real life application of research makes me so excited at the prospect of possibly conducting my own research at some point in the future.

As the program comes to an end, I can’t help but run through all the experiences we’ve had over the course of this trip. We were able to do and learn so many different things in such a short period of time. I never thought that there would be so much to do in such a small country, and we weren’t even able to get to everything. This trip will always be one of the coolest things I’ve ever done in my life and I plan on revisiting Costa Rica at least one more time in case I start to forget what a truly amazing place it is.

Peter Saunders

Providence College

Chasing Red

A visiting professor named César Nufio came to lead one of the research projects here at La Selva Biological Research Station.  While here, he also gave a few lectures, and in one of them he told us about the research he does at his university back in Colorado, where he is working on a long-term project studying the effects of climate change on crickets.  He talked about thermal performance curves, and the idea that organisms function optimally at a certain temperature, but when their body reaches temperatures too far above or below the optimum temperature their metabolic functions and performance in activities such as jumping starts to diminish, until they reach a thermal maximum or minimum when they can no longer function at all.  This is particularly relevant to ectotherms because they cannot regulate their body temperature metabolically, so their environmental conditions have a large impact on their internal temperature. 

            Andriana, Erin, and I decided to work together on another research project, and we began to wonder if since the lowland wet forest of La Selva is already so hot, some organisms might already be operating at or above their optimum temperature, meaning further warming would decrease their fitness.  We decided to work with the small and charismatic red and blue poison dart frog, Oophaga pumilio, and since it’s an ectotherm its body temperature could potentially rise at the same pace as that of the local climate.  To test this idea, we decided to compare the frog’s jumping ability at temperatures slightly hotter or colder than what they experience in the forest, and to test their thermal preferences since animals often prefer temperatures close to their thermal optimum.  It was easy to spot frogs in the forest; O. pumilio is so abundant at La Selva that we merely had to walk through the undergrowth and one would appear out of the leaf litter every five or ten meters, a small red flash hopping away.  The frogs near the beginning of the trail were apparently fairly accustomed to people passing by on the trail so they weren’t too difficult to catch, and with practice we were able to catch up to 30 in two hours.  However, we needed to catch frogs each morning and release them by the next and couldn’t catch frogs at the same place twice, so each day we went further down the trail.   By the fourth and final day of data collection, we were a few kilometers into the forest where the frogs were much more skittish.  Many probably hid when they heard us coming, and the ones we did see would often disappear into the leaf litter before we could catch them, and that morning we only caught four.

            Back in the lab we tested each frog’s jumping ability at the ambient outside temperature as a control by placing the frog on a plastic lid covered with paint to get some on its feet and let it jump on a white sheet.  They left very cute little frog footprints, and we measured the distance between them to see how far each of the first five jumps were.  We then either warmed the frog up using a heat lamp or cooled it down in an air conditioned room and did the same jumping test again.  To see if the frogs preferred a certain temperature, we put them in a thermal gradient we made out of a wood box and some heat lamps and let them roam around for 15 minutes. 

            We were somewhat surprised to find that the frogs jumped the farthest when they were at the hottest temperatures we tested, around 35°C.  Frogs that were at a higher temperature in the field visited warmer spots in the gradient, and these temperatures were often higher than what they were at in the field.  While this is certainly good news for the frog and suggests that it may be able to tolerate warming of at least a few degrees, weren’t sure how to present these results at first.  Many people predict that amphibians will be particularly vulnerable to global warming since they are ectotherms and many require water to keep their skin moist and to lay their eggs in.  Our results don’t discount the other potential threats of warming temperatures, or suggest that O. pumilio.  It may still affect other species in the same ecosystem, which would in turn affect O. pumilio, and further research would be needed to see if warming temperatures will change precipitation patterns and how that would affect O. pumilio.  However, it is heartening to know that not all species will respond to climate change in the same way, and that some may even be better at tolerating it than we expect.

Sequoia Grettenberg
Wesleyan University