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In Costa Rica, Field Research Deepens Insights into Tropical Rainforests

A biology seminar highlights the vital role of advocacy for one of the world's most diverse ecosystems
News Staff | Mon, Apr 14, 2025

For Jackie Sastry, A26, to trek through the Costa Rican rainforest earlier this year was to take a sensory journey. She recalls the booming calls of howler monkeys, smells of the forest just before it rained, and tree branches carpeted in mosses, orchids, and ferns.

“I took photo after photo so when we got back to the research station I could ask: ‘What’s this plant?’” she said. “I didn’t know anything! Just being there taught me so much more than I would ever have learned from reading journals.” 

The burning curiosity to know, the enthrallment that comes with seeing nature’s extraordinary abundance—these are at the heart of the student experience in Tropical Ecology and Conservation. The fall semester seminar is offered every other year and culminates in a 15-day research trip over winter break to Costa Rica, one of the most biodiverse countries on the planet.

The longest-running, credited course at Tufts that involves international experiential learning, Tropical Ecology and Conservation immerses students in hands-on field research and aims to deepen awareness of the challenges involved in protecting the world’s shrinking wild spaces. The itinerary includes meeting with local experts and community members devoted to conserving the rainforests they call home.

Biology Professor Colin Orians originated the course in 2001. The structure of the class reflects his own ties to Costa Rica, going back to the “magical” experience he had conducting graduate school research there some 40 years ago. 

He sees Costa Rica as a living laboratory for his class, which has intertwined goals: to give students a deeper appreciation for the scientific method, to provide an immersive scientific and cultural experience, and to strengthen their sense that they can make a difference.   

“Immersive learning experiences are so important today if we want to inspire students to understand and think about the world around them,” he said. “Our goal is to help students explore both the challenges and the solutions facing rainforests and other vulnerable ecosystems around the world, but if students don’t have the opportunity to build a sense of wonder for nature, it is hard to imagine them making decisions to fight for the conservation of biodiversity.”

For the past two trips, Orians has been joined by Anthropology Professor Zarin Machanda, director of long-term research at the Kibale Chimpanzee Project in Uganda. Machanda appreciates how the seminar gives students an opportunity to identify and tackle a scientific question of their own, rather than simply supporting someone else’s work. 

“It gives me endless satisfaction watching them grow as scientists and thinkers,” she said. “But the most fun part of the trip for me is getting to share the magic of the rainforest with students,” she said. “They never lose their wonder. And there is nothing better than seeing the forest through the eyes of the students experiencing it for the first time.”

Jackie Sastry and Blythe Elderd with one of their artificial caterpillars they made to reveal patterns of predator behavior.
A baby red-eyed tree frog, photographed just after it emerged from a pond at Rancho Quemado.
Anthropology Professor Zarin Machanda and Biology Professor Colin Orians, bring enthusiasm and expertise to the study of tropical ecology in Costa Rica.
Colorful species endemic to tropical rainforests include the common basilisk, a lizard found near streams and rivers.
The rufous motmot, a bird that thrives in the thick understory of Costa Rica's lowland forests.

Sastry and Blythe Elderd, A26, decided to explore predator patterns in tree fall gaps and the adjacent understory. Tree fall gaps are spaces that open in the rainforest and are filled with sunlight, and often predators.

Their project included hand-crafting more than 100 green clay “caterpillars” intended to attract predators, such as birds, rodents, spiders, and lizards. They anchored their creations in a wet rainforest and a seasonally dry site to test their hypothesis: There would be more nibbles from predators on the clay caterpillars closer to the edges of the gaps, where the odds were higher for quick exit should the predators feel threatened.

The students were, it turns out, correct. “Knowing that we designed an experiment and we were able to follow it through and we got significant results, that was a big confidence boost,” said Elderd.

Gabriel Molnar, A25, a biology and cognitive brain science double major, was among the 16 students on the trip this past January. He and Anne Kelley, a biology graduate student, developed a research project based on their shared interest in freshwater conservation.

They chose to investigate the impact of banana, pineapple, and palm oil plantations, through deforestation, fertilizers, and pesticides, on the quality of streams. Like their classmates, they had done considerable preparation in Medford, first reading widely about tropical ecology, finding a gap in the literature that resonated with their own interests, and then drafting a hypothesis and writing a research proposal.

Their plan: to look at specific metrics (including acidity and nitrate and phosphate concentrations) to determine freshwater health at upstream and downstream sites in two locations. 

When they gathered their data, they were surprised to find few differences between samples upstream and downstream of land used for agriculture. Where there was variation, it was not consistent across sites.

“It’s likely we can chalk up our findings to fact that we were just getting snapshots of each river, rather than a holistic look at each sample site,” said Molnar. 

Still, “this was a project I am proud of,” he said. “The process of thinking through and doing this project with classmates and incredible instructors was one of the more collaborative experiences that I have had at Tufts.”

Over the years at Tufts, Orians’ passion for Costa Rica has inspired hundreds of students, many of whom say the course affirmed their decision to go to graduate school. 

The rural community of Rancho Quemado was a gateway for Tufts students to explore the natural wonders of Costa Rica. Field research projects looked at specific ecosystem questions, with Gabriel Molinar and Anne Kelley (far right), designing their project around the impact of local plantations on stream chemistry and water quality. Photo courtesy of Colin Orians

One confirmation of that lasting impact is the response from alumni to ongoing requests for funding. Through a recent crowdfunding campaign, graduates of the course contributed more than $10,000 in one month toward financial support for current and future students who need help with travel expenses. 

Natalie Brownsell, A24, is grateful for the opportunity the class provided to test her interests when she was a junior. After graduating with a degree in Applied Environmental Studies, she is now with the California Department of Fish & Wildlife; her current fieldwork takes her throughout the Sacramento River watershed to monitor threatened Chinook salmon and Central Valley steelhead. 

Brownsell didn’t have much experience doing scientific research before she went to Costa Rica, but the class helped her “to gain confidence in my ability to make real contributions to scientific understanding,” she said. “The experience gave me an opportunity to challenge myself and discover my passion and skill for fieldwork. The nature of scientific research and field work is this: You won't know if it's for you until you try—you have to immerse yourself in it to find out.”