Valeria Aspinall was at the Tapir Valley Nature Preserve in northern Costa Rica the day an expert herpetologist declared that the tree frog living there is a distinct species, something that had not been recognized by science.

“When he saw a video of the frog and heard the frog calling, he said, ‘This is something new. This is something I’ve not seen either in Central or South America,’” she said. “I was lucky enough to be there that night. It was my first experience with the amphibian world and how I fell in love with frogs.”

Aspinall is now at the Odum School of Ecology working on a master’s degree with a Spencer Fellowship and conducting research that she hopes will protect the very rare, critically endangered frog, which has only been found in a 20-acre wetland within the larger nature reserve adjoining Tenorio Volcano National Park.

It was the call of the tiny tree frog that first drew attention in 2018, when the founder of the private nature reserve, Donald Varela-Soto, kept hearing the amphibian. He finally saw a male of the species that same year.

Aspinall, then working as an intern for Costa Rica Wildlife Foundation, saw the first female in 2020.

The frog is tiny—just 2 centimeters, or about the size of a thumbnail.

Scientists named the species Tlalocohyla celeste in honor of the turquoise waters of a local river, the Río Celeste. A formal description of the species has been published in the journal Zootaxa, but little is known about its mating habits, diet or even how many exist.

No one knows for sure if the frogs on the reserve are the only population of the species that ever lived, if the frogs once lived in a wider swath of Central America but lost habitat, or if they still live in other places. The Tapir Valley tree frog shares the nature reserve with the native Baird’s tapir, jaguars, collared peccaries (pig-like animals also known as javelinas) and many exotic birds.

It was the frog’s own call that drew attention when it still was unknown to science. Aspinall now plans to use the frog’s call to find out important information that might be key to its survival as a species.
“Our main goal is to ensure survival of the species in the long term. From my scientific background, I want to provide information to inform conservation strategies or management actions, such as creating a monitoring program for the frog,” she said.

Aspinall solicited grants to pay for a climatic station, water-level loggers and acoustic recorders to study the wetland and begin to understand what environmental factors influence the frog’s calling activity, which gives clues about reproduction.

“I want to build a long-term monitoring protocol for this species that is not invasive, and acoustics provide that opportunity. When you have a species that might be microendemic, living only on 8 hectares of land, you don’t want to be doing any sort of manipulation that might affect the population,” she said. “Bioacoustics provides a tool to study the frog without having to intervene with the animal or its habitat.”

Understanding the frog’s movements and vocalizations will help Aspinall create a monitoring plan and define what’s important in a conservation strategy. Something as small as one species of grass edging out another species might make a difference if the frog prefers one species for laying its eggs.
“We’re studying a critically endangered frog in a wetland system, and wetland systems are very dynamic,” she said. “We don’t know how the vegetation behaves in this wetland in a given year. Sometimes if we have a longer dry season, then these grasses can encroach a little bit more, but we don’t know how that affects the frog.”

Aspinall completed an undergraduate degree at Colorado State University in 2020 before returning to Costa Rica to figure out her next career step. She’s always loved nature and wound up at the Tapir Valley reserve as a volunteer and then an intern.

“I grew up in the city, but my family was very adventurous. We always were going camping or snorkeling—just doing something outdoors,” she said.

Aspinall met Odum School faculty member Amanda Rugenski by chance, when she bumped into her at the nature reserve in the fall of 2023. Rugenski, who leads the Odum School’s semester-long Costa Rica tropical ecology study-away program, was at Tapir Valley to scout a new field site and meet Jorge Rojas, the TA for the fall 2023 program, who at the time was a UGA Ph.D. candidate conducting research on tapirs.

“I told her about the frog and all the questions I have, all the things we don’t know,” Aspinall said. And she said, ‘You know, let’s go get a beer and talk about frogs.’ So, that’s what we did.”

Aspinall is completing her first year of coursework toward a master’s degree and returning to Costa Rica this summer for fieldwork.

“When I heard Valeria speak so passionately about her research and the conservation questions it raised, I immediately thought this is exactly the kind of student we should be supporting in our master’s program,” said Rugenski. “She was an ideal fit for our Integrative Conservation and Sustainability area of emphasis. She is now pursuing her degree while actively contributing to the conservation of a highly imperiled species.”

The Spencer Fellowship, named for John Kyle Spencer, is managed by the River Basin Center and supports selected students with a passion for freshwater conservation and plan for a career in management and conservation of freshwater ecosystems.