Monday, November 28, 2016

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

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