App aids annual firefly abundance survey in tracking urbanization effects

By on October 31, 2013

A firefly bioluminescing (Credit: yellow_bird_woodstock, via Flickr)

The bioluminescent flashes of fireflies are a surefire sign of summer across much of the United States. But as their preferred habitats are lost to increasing urban development, researchers at Clemson University are turning to citizen scientists to detect whether the beetle’s population is also in decline.

The Vanishing Firefly Project, launched in 2010 by Clemson scientists Alex Chow and Juang-Horng Chong, is an effort gather long-term firefly population data across South Carolina from volunteer observations. Entering its fifth year, the project has seen participation grow ten-fold since introducing an iPhone app to help collect and submit surveys tagged with location data.

Chow, an assistant professor in the School of Agriculture Forestry and environmental science, said the project is using the firefly as an indicator of general environmental health. The insect relies on particular ecosystems that feature moist soil and organic litter–habitats that aren’t highly correlated with highways and shopping malls.

“As an insect, they are quite sensitive to environmental change,” Chow said. “Their defense system is really weak. So whenever there’s an environmental change, you can see the population change really fast.”

The firefly is also an ideal species for the survey because its flashing displays mean volunteers can forgo the trapping equipment down-in-the-dirt field work typical of  insect surveys.

“It’s very easy to observe,” Chow said. “They’re bioluminescent at dark so people can see them easily. Everyone from elementary school up to retired seniors can be involved in this project.”

In its first year in 2010, the annual survey asked volunteers to count fireflies across a single wildlife refuge. It later expanded to a state-wide survey with participants counting fireflies wherever they could–say, a park or their yard–and submitting the data to the researchers through a website.

For the 2013 survey in June, the projected launched a free iPhone app to ease data collection and submission. The Firefly Flash Counter launches a one-minute countdown timer and adds to a tally each time the user sees a firefly and taps the screen. Once the minute is up, users enter the species of fireflies they observed and the type of habitat they surveyed. The app sends the data to the project server along with time and location data. The 2013 results are compiled on an online map.

Screenshots from the Firefly Flash Counter, showing the counting and data submission screens (Credit: Clemson University)

Before launching the app, the survey had around a hundred participants. This year, that grew to more than a thousand. Chow said that could keep growing.

“We are expecting if we can expand it to Android and other devices–and I expect mobile phones will become more popular, I expect the people will be increasing for this coming year,” he said.

The researchers haven’t yet been able to draw any conclusions from the data, Chow said. One issue they’re dealing with is the limitation of collecting data on a single day during a coordinated event. Limiting the time window for the survey helps control the spatial distribution of the data, but Firefly emergence depends on temperature and precipitation. The data from one year to another can vary based on the weather on that particular year. Volunteers reported seeing many more fireflies in 2013 than in previous years, but the weather on the night of the survey was also dry relative to 2012 and 2010.

So the researchers behind the project are still working on how to best interpret the data from their volunteers. The utility of the data will also grow as time passes and more annual surveys build the dataset into a long-term one. Though it’s clear to Chow that firefly habitat is shrinking as urban development advances, it will take more data to show that the fireflies are disappearing along with it.

“That’s the big question for our study: Is it really vanishing?” Chow said.We need more long-term data to support it.”

Top image: A firefly bioluminescing (Credit: yellow_bird_woodstock, via Flickr

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