Tadpole scientists: Two NH kids co-publish a research paper on frog eggs

When 8-year-old Ava Calsbeek spotted some wood frog eggs in a pond near her family’s home in Hanover, she noticed they were black on one side and white on the other.

Ava showed her dad, Ryan Calsbeek, and her 11-year-old sister, Izzy, who wondered why that was happening.

“And so I asked if the black was so that they could absorb more sunlight to grow faster,” Izzy said.

Ava and Izzy decided to test how changes in temperature and sunlight affect how wood frog eggs grow, and whether it mattered if sunlight came from above or below the eggs in order to determine if different sides of the eggs absorb heat differently.

They put the frog eggs into two batches: One tub had direct sunlight coming from above the eggs, while the other had a mirror underneath the tub so that light could be redirected up towards the eggs.

Ryan Calsbeek

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Ryan Calsbeek

Nearly two years after first noticing the differences in the eggs and running their experiments, the sisters co-published a research paper with their dad, Ryan, a professor of biological sciences at Dartmouth College. The three found that while the different sides of the eggs didn’t absorb heat differently, communal nesting habits kept the frog eggs warm — especially for the batch with a mirror underneath, since the reflection mimicked a colder environment.

“It’s better for the frog eggs to be in groups because they heat themselves,” Ava said of the findings.

Ryan Calsbeek said the results mirror how communal nesting habits among species, even in New Hampshire, are being directly impacted by temperature shifts due to climate change.

“We've had very early springs where the ponds thaw,” he said. “Frogs come in because they think it's time to lay their eggs and then we'll get an unexpected cold snap soon thereafter.”

That sort of unpredictable fluctuation in temperature, Ryan said, can leave different species unprepared for drastic changes in climate.

“A lot of these populations are experiencing higher levels of mortality, not just because of warming, but because of the hot-cold cycles that are relatively unexpected, relatively new,” he said.

Running these experiments together to understand what was happening with the frogs and their eggs has left an impression on Ryan, Ava and Izzy.

“These two are certainly the youngest field scientists I've ever interacted with,” he said.

The two sisters would pass off the data they collected, diagrams of the developing embryos and weather notes. Ryan would transcribe their observations and run statistical analyses of the data the sisters had written down in a notebook.

“The data notebook is a great memory with their little handwriting and the drawings that they made of the developing tadpoles,” he said. “Something we'll keep forever.”

Ryan Calsbeek

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Ryan Calsbeek

Ava said that looking back, there was one part of the experience she especially liked.

“I really liked going out and catching the frog eggs to do the experiment,” she said.

“They kind of feel like Jell-O,” Izzy added. “It makes your hands dry.”

The sisters are already thinking about more experiments to do.

“I think it would be really cool if people put frog eggs in, like, different temperatures in different climates and see which one is best for different frogs,” Izzy said.

Ava wants to put eggs of different frog species in close proximity to each other, and see how they might interact.

“Like poisonous frogs and wood frogs,” she clarified.

They’ll have another notebook at the ready if they decide to put these questions to the test.