The Túngara Tavern

Meet the Lab! 

Left to Right: Julianna Mendez ’23 (working for Dr. Michael Caldwell), Angelina Piette ’23, Dr. Alex Trillo, Alessandro Zuccaroli ’25

In a far away lab …

Deep in the forests of Gamboa, Panama lives the Rebel Túngara frogs who plan their next move against the Trachops Empire and their Corethrella troopers. Having won their first victory, the Túngara managed to find mates before the Empire could use their ultimate, secret weapon, ECHOLOCATION, with enough power to destroy an entire army of frogs. 

Pursuing to research the Empire, the Trillo Lab races back to STRI home base with data that can save the Rebellion Túngara and restore freedom to the forest …  

Male-male Túngara aggression! *cue the Star Wars theme song*

But first, where are we? An Introduction to Panama and Gamboa:

To most of the world, the Republic of Panama is best known for the Panama Canal that connects the Atlantic and Pacific Ocean. Unlike one would expect, the Atlantic Ocean borders northern Panama, whereas the Pacific Ocean lies to the South. Between these borders, Panama contains lush rainforest, teeming with the high biodiversity characteristic of the tropics. 

The presence of the Panama Canal is well known. Something that the world is less likely to know, but that is just as crucial to Panama, is the indigenous population. Today, there are seven indigenous peoples in Panama, including the Wounaan, the Guna, the Emberá, the Ngäbe, the Naso Tjërdi, the Buglé, and the Bri bri. According to a 2010 census, 12 percent of the total population, or about 418,000 people identify as indigenous. These seven indigenous peoples occupy a combined 1.7 million hectares of land. Near the town of Gamboa, the Wounaan people live in the surrounding forest, and they are well-known for their craftsmanship of ancestral woven baskets, as well as their proficiency in canoes. 

STRI at Gamboa, Panama

Lying close to the Panama Canal is the town of Gamboa. Gamboa is within the Canal Zone, a geopolitical border that previously denoted American owned land that extended in a radius around the Canal. The United States government left the Canal Zone on December 31st, 1999. Located within the Canal Zone, Gamboa is our home for the next couple months. Gamboa is a hub for scientific research, as it houses one of several Smithsonian Tropical Research Institute (STRI) sites in Panama. Scientists at STRI work on bats, frogs, snakes, butterflies, and much more! That said, Gamboa houses much more than STRI scientists. Many others reside in Gamboa, contributing to its quiet, welcoming atmosphere. As a result, there is a tangible sense of community, as many residents are connected by their love of conducting and sharing their research.  Furthermore, the Gamboa Baking Company, operating out of a Gamboa resident’s garage-turned-kitchen, provides a great place for all members of the community to sit and relax, and even better baked goods. Also, Gamboa houses the Gamboa Rainforest Reserve, a resort that serves as a tourist attraction to many people, while some STRI employees utilize the forest near the resort to conduct research at sites such as La Chunga and La Laguna. The majority of our research is conducted in the forest of Soberania National Park, accessed via Pipeline Road. Pipeline is a hotspot for STRI scientists who all utilize the nearby, lush forest to conduct a plethora of scientific research. Each time you walk down Pipeline, you will encounter other scientists gathering data, people absorbing their surroundings while hiking, and a wide range of breathtaking wildlife.

 Sources

“The Indigenous World 2022: Panama.” IWGIA, International Work Group for Indigenous Affairs, https://www.iwgia.org/en/panama.html. 

“History of Relationship.” EOP, Embassy of Panama, https://www.embassyofpanama.org/history-of-relationship.Few for Change. “An Overview of Panama’s Indigenous Communities: Part 2 – Eastern Panama.” Few for Change, Few for Change, 10 Nov. 2020, https://www.fewforchange.org/blog/2020/11/an-overview-of-panamas-indigenous-communities-part-2-eastern-panama.


Background and research question:

The main interest of the Trillo lab is the effect of calling neighbors on eavesdropper attraction in frog choruses. In previous years, the Trillo lab has mainly focused on mixed-species frog choruses and heterospecific neighbors. However, this summer, the lab’s focus is to understand how attractive neighbor calls can influence the risk of predation within a single species. More specifically, the lab will be focusing on the Túngara frog and its predators: Trachops cirrhosis, or the fringe-lipped bat, and the micropredatorial Corethrella midges. 

Fringed-lipped bat preying on a Túngara frog
 [Photo credit: A. Baugh] Ryan, Michael. (2011). Replication in Field Biology: The Case of the Frog-Eating Bat. Science (New York, N.Y.). 334. 1229-30. 10.1126/science.1214532.

For some background information, it is important to understand the intricate cost-benefit relationship associated with animal’s mating calls. While a call’s purpose is to attract females for reproduction, it also has the potential to attract eavesdropping predators. Moreover, different calls might elicit different levels of interest from eavesdroppers. Research at the Trillo lab has shown that hourglass treefrogs, which possess a less attractive call, experience an increased risk of blood-sucking midge predation when calling next to túngara frogs, which possess a more attractive call (Trillo et al, 2016, 2021). This is consistent with the Collateral Damage hypothesis, which states that attractive callers may increase the risk of predation on neighboring individuals by increasing predatory attraction to the entire aggregation. On the other hand, the Shadow of Safety hypothesis states that the more attractive caller will incur the increased risk, sheltering other less-attractive, aggregated individuals from the risk of predation. Thus, when two or more neighboring individuals utilize call types of differing attractiveness we call it asymmetric attraction (Trillo et al. 2019).

Túngara frogs in amplexus making an egg clutch with Corethrella midges swarming
Provided by collaborators, Dr. Rachel Page and Dr. Ximena E. Bernal

Túngara frog

The idea of collateral damage or shadow of safety across species could also be applicable within a single species, if individuals within that species use more than one type of mating call, and if one of those signals is more attractive to predators than the other. This is the case for Túngara frogs. Male túngaras have two types of calls: a simple and a complex call. The simple call consists of a single whine, whereas the complex call consists of the same whine with an additional syllable called a “chuck” at the end. These calls differ in their attractiveness to both females and predators, setting up a cost-benefit relationship. Calling simple calls poses a lesser risk of predation, but it also is less attractive to females. On the contrary, calling complex increases attractiveness to females and predators alike. These predatory interactions allow us to further investigate the Collateral Damage and Shadow of Safety hypotheses.

In nature, a solitary male túngara frog will call simple. However, in an aggregation of male túngaras, they will switch to complex calls to attract females while potentially diluting their individual risk. With this in mind, our research question this summer is: Do simple calling túngara frogs experience collateral damage or shadow of safety when calling next to a complex calling neighbor? We hypothesize that the highly attractive signaling complex calling neighbor Túngaras will increase the risk of predation and parasitism of their simple calling neighbors. 


Methods of research :

Data Collection

Walking through Pipeline to our site (Soberania National Park)

Our research consists of various combinations of Túngara acoustic playbacks. We set up two speakers at one of our six sites for different treatments (Simple-Simple, Simple-Silent, Complex-Complex, Complex-Silent, or Complex-Simple) in order to analyze the differences in eavesdropper predator attraction to these different types of calls in a duet. 

We set up camera traps to record bats visiting each speaker, and we place fly traps above each speaker to capture the Corethrella midges attracted to each type of call.. After the experiment is done, we count the number of flies present and carefully upload the bat videos taken at each site in order to score them for bat visits. The experiments are recorded for 80 minutes.

(Warning, all our experiments are done at night, so wear your headlamps and watch out for snakes!!)

Setting up speakers
One of our resting sites at the Soberania National Park, where we wait for a trials to finish

While our trials are running, we get to wait nearby and listen to the forest. When you’re extremely quiet, you can hear some of the most amazing choruses from many different species in the silence of night. 

Bat Scoring

We score bat videos blind to the treatment and use pre-determined behavioral criteria to decide whether a sighting is a bat visit to the speaker or not. A bat will visit the speaker in many unique ways: flyby (swoop down towards the speaker and swoop up), hover, or circle around the area (maybe a half circle, once, or twice) to locate the frog.Not only do we see bats in the video, but we also sometimes find really cool nocturnal species passing by the camera (and some even seem interested in the speaker!). 

Midge Counting

Collecting the midges after a trial 

             The day after our experiments, we count how many midges were collected in each treatment (blindly as well). We use our headlamps to see the little guys stuck in the sticky glue and a pair of tweezers to count and pull them off.! Most days, we’ll count hundreds or a thousand files in a single treatment. Next time you are annoyed by a mosquito, imagine what a calling Túngara feels like!


Daily life in Panama

            Most of our daily life in the tropics consists of working through all the different steps of research. From scoring bat videos, counting flies, troubleshooting with equipment, and 3-hour night hikes to run new experiments, we are constantly involved in data collection. However, on our days off, we experience some great adventures that Panama and STRI has to offer. 

Poster session at STRI

            At STRI, we have already attended several talks and we also attended a poster session that was given by the research fellows. Over 20 people presented their research and latest findings. We saw posters that focused on marine paleoethnology, botany, mammalian biodiversity, vampire bat behavior, butterfly genetics, climate change, and microbiology!

Karen Warkentin’s talk on queer perspectives in behavioral diversity studies

After the poster session, the event ended with a talk by Dr. Karen Warkentin, who discussed queer perspectives in behavioral diversity and disrupting binaries set upon by previous research. She explained how science is limited due to normalized human concepts (ie independence of gender and sex relationships) and interpretations being placed into biological studies and knowledge. Warkentin studies vibration behavior and sexual selection in frogs and she has found wide diversity and interspecific variation of communication and parental care across species. 

Julianna and Alessandro at the poster session

Other times, we enjoy going on day-hikes and exploring the tropical forests. The greatest part about living in Panama is seeing new species of plants and animals everywhere you look. Species you might only see live in the zoo otherwise, here we experience naturally, in their native lands. It’s like watching a National Geographic documentary, but in real life! We’ve seen hundreds of species, from the agouti that chomp on coconuts in our backyard to the howler monkeys signaling on-coming rain. You’ll never see the same forest twice, 

Angelina finding a cane toad in our backyard

each time we hike Soberania National Park, it changes; these forests are ever changing. And with every transformation of our surroundings come new experiences. The things you see are unique and unlike anything we’ve ever witnessed before, like an iridescent cicada hatching from her shell, a chorus of dozens of Túngara calling in the rain, a Fer-De-Lance snake curled up by our site (no worries, we were careful!), toucans flying in the distance, an ancient tree with river-like roots, just to name a few. And yet, we’ve seen barely anything compared to what these forests have to give. As one of our colleagues said, “in the rain, Panama looks like ‘Rainforest Café’ has come to life”, and I couldn’t agree with her more.

As of now, we are halfway through our time in Panama and have so much left to explore! We will continue our night hikes, discovering new species, and collecting data before our next adventure in Costa Rica, where we’ll discuss our new findings at the Animal Behavior Society Conference. We hope you enjoyed the Túngara Tavern! May the forest be with you. 

          

           


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