The Silence of the Frogs

           

Walking through the pristine forests of Monteverde, it is easy to imagine that the forest hasn’t changed that much in the past 50, 100 or even 200 years. But that assumption would be wrong. Even though the forest is currently full of many frog calls, about 20 years ago, most of the frogs vanished leaving the forest silent.

            The two biggest schools of thought surrounding this crash, are global warming, and the chytrid. fungus. As we learned about the evidence supporting each theory, all I could think about were the dead frogs. How did over half the frog species in Monteverde disappear almost without anyone noticing. Frogs are iconic in Monteverde appearing on t-shirts, and bringing in a lot of tourist money, but most frogs have had little to no research done on their species, and many species don’t occur anywhere else in the world. While some species of frog still haven’t been seen in the 20 years since this happened in Monteverde, 75% of the most common pre-crash species have been spotted since.

            After the lecture, we walked outside to find frogs, and we didn’t have to go far. The first frog was on the plant right by the door. As we continued on our walk we saw dozens of frogs in a short period of time. My favorite species in Monteverde, the red eyed leaf frog, looks very similar to the red eyed tree frog. These little frogs spend most of their time in the canopy, so they have huge toe pads that help them climb, and they are excellent jumpers. As I was taking a picture of this frog, the flash must have caught his attention, because all of a sudden he turned to stare at me, making a great photo opportunity. This behavior is used as a defensive mechanism, with many predators being deterred when the frog opens its red eyes in the predator’s direction.

            Another thing that was evident in the forest sounds was the wide range of frog calls occurring. To my untrained ear, it sounded like there were at least 10 different species in the small area surrounding me, but as I learned each frog can make multiple different calls. There are male advertisement calls, distress calls, courtship calls, release calls and aggressive calls. This wide variety of calls could make one frog species sound like at least 5 different species of frogs. The other interesting thing about calls is how cryptic they can be. Many frogs call to let potential mates know where they are, yet after listening to a call for 10 minutes, I was still unable to spot the glass frog making the call. To avoid detection from predators, and me, frogs will infrequently make the call, or hide really well while they are making their calls.

            After a long night hike, I may not have found my glass frog, or been able to see some of the species that haven’t reappeared after the crash, but I was able to see some amazing frogs, and learn about how they are coming back, and even expanding their range to make a stronger frog population. 

Rachael Lewandowski-Sarette 

Northwestern University

How Can I Help?

As we near the end of the semester, I am growing increasingly anxious about what to do next. I have one more semester at Duke, and then I plan on taking a gap year before going to grad school to specialize in herpetology. I’ve always said I wanted to do conservation biology with herpetofauna, to study the animals I love in a way that allows me to help them. But how on earth do I turn that desire into anything tangible?

As we move from field station to field station here in Costa Rica, I keep hearing people say how much we still don’t know about all of the herps that live here. This has especially been true here in Monteverde. We met Mark Wainwright, who is somewhat of a celebrity among the biologists in Costa Rica. He literally wrote the book on mammal identifications here, and he knows an amazing amount about birds and herpetofauna too. But as he educated us on the variety of calls frogs use to communicate different messages, it became apparent how much information we were missing. Although a frog may call for advertisement, aggression, distress, warning, release from amplexus, or courtship; the majority we hear (and therefore are able to record) are for advertisement. Of the 65 or so species found in Monteverde alone, how many sounds are yet unknown? And if we don’t even know what sounds these frogs make, just think of all the information on their morphology, adaptations, and behaviors that remain to be studied! There are species that go missing for years at a time and then pop back up seemingly from out of nowhere. There are also population crashes and occasional recoveries and then unexplained range expansions or contractions. There are a myriad of things we don’t know, studies that could be done, and information to be discovered. The possibilities are enthralling.

And yet when I think ahead to our independent projects at Palo Verde, I’m at a loss. I’ve been brainstorming all kinds of questions and designs, but the small scale of these projects (only four days of data collection) is quite limiting. And I find myself asking more and more frequently – how can I study something that will provide useful information? This is still just the beginning of my research endeavors, so I realize it’s probably aiming way too high to expect anything important to come from such a study. But it feels almost wasteful not to strive for that when we have the opportunity to work in such important ecosystems as the dwindling dry forests or seasonal wetlands in Palo Verde.

I’m generally of the opinion that the pursuit of knowledge for the sake of knowledge is worthwhile. However, in the current situation of political disarray, climate change, under-regulation of environmental risks, and all the other problems that we as humans have created, I feel that the subjects of studies being done now and in the coming years are of the utmost importance. These organisms cannot afford for us to squander time finding out interesting trivia. Populations of amphibians and reptiles are dwindling worldwide, and there isn’t much time left to change course. There may not be any time left at all. So we must use every possible resource to find helpful answers.

Going back to where I started – I still don’t know exactly which species, or for that matter even which order of herpetofauna to specialize in. And this project may simply be a stepping-stone as I learn how to design studies and begin to enter the research world. But I do know that somehow, in the long term, I will find a way to put my time and energy to use working toward the preservation of these incredible animals. 

Madison Harman

Duke University