The Results Are In! Summer 2021 - Data Collected and What It All Means
Written by A. Srivastava
The summer of 2021 was a great year for the launch of the Atlanta Firefly Project! Founded by Kelly Ridenhour as part of her master’s thesis, the project aims to collect data on fireflies in the Atlanta area to further understand firefly biology, assess species distribution and habitat use, and promote firefly conservation.
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There has been a decrease in firefly populations across the US, due to deforestation, habitat loss, and climate change, and as a result of urban expansion and development projects.¹ Kelly’s master’s thesis focused on the impacts of urbanization and land management practices on firefly distribution and abundance, with a specific focus on the Big Dipper firefly, Photinus pyralis. In order to collect data for research and promote firefly conservation, the Atlanta Firefly Project recruited as many as 1,500 community science volunteers to participate in the project and over 450 volunteers to monitor firefly species in their backyards and across the Atlanta area. Volunteers submitted data, two nights in June and two nights in July, from their own yard, whether that be their townhome, apartment, detached home, etc. about what and how many lighting bugs they saw, as well as specific details about how the conditions in their yard, including house and street lights, pesticide use, and lawn fertilization. All this information helps us learn a little bit more about how urban lighting and lawn care affects firefly species; it’s safe to say that we reached our goal! Here are the results.
The project collected data from 1,022 sampling events from a total of 482 residences and parks. These came largely from in and around Atlanta but we received a few submissions from further away around Dalton, Athens, Peachtree, Griffin, and Carrollton. Most of these entries came from residential areas with typical residential greenery like grass lawns, bushes, and trees which are common habitat areas for fireflies living in urban regions.
With the data from the survey, Kelly was able to conduct a more in-depth analysis of how the types and health of vegetation affect the abundance of fireflies. It’s no surprise that as the amount of healthy vegetation in an area increases, so does the number of fireflies, indicated by a higher flash count. The right-hand side of this figure represents the most vegetation and higher firefly flash counts. In contrast, the left-hand side of this figure represents unvegetated areas, including bare earth, roads, sidewalks, where firefly flash counts were much lower.
Graph of Firefly flash count across vegetation type adapted from Kelly Ridenhour. The scale of firefly flash count is normalized by the highest flash count. The scale of vegetation is calculated from the amount of vegetation with a 30 meter buffer (sum of NDVI: log 10).
Kelly was also able to use land management data from the survey to assess the effects of intense land management practices on firefly abundances. Her analysis indicates which land management practices would result either in a decrease of firefly abundance, an increase, or no change. In the figure below, the dotted line indicates no change in firefly abundance based on the land management practices and the different colors reflect the length of time that practice has been in use (blue: less than three years, orange: at least three years). Based on her analysis, activities like mowing, using fungicides, or using insecticides have no significant effect on firefly abundance (we can tell because they overlap the dotted line). On the other hand, practices like irrigating the land, using mosquito services, fertilizing your lawn, using artificial lights at night, and removing leaf litter are likely to have a significant negative effect on the abundance of fireflies in your yard (they fall below the dotted line). In contrast, the use of herbicides leads to an increase in firefly abundance (it falls above the dotted line). Surprisingly, there was very little difference whether the land management practices were recent land management decisions or if they were practices that had been continued for many years (in each category the orange and blue both have the same effect).
For a more detailed video where Kelly shares the results of the Atlanta Firefly Project Summer 2021² click here: https://www.youtube.com/watch?v=zDDKrbdtAKI
Understanding how the decisions we make affect firefly abundance can help us better protect them. What can we do to support our firefly populations? Here are some ways to help that you can do fairly easily³:
Reduce artificial lights. Specifically, do not keep them lit throughout the whole night, particularly during the spring and summer firefly seasons.
Avoid mosquito spraying, especially for multiple years. For more tips on mosquito management, visit the Beecatur project website, or check out suggestions from Trees Atlanta and the Xerces society.
Plant native trees and leave the leaves alone. Trees and their fallen leaves are important habitats for both adult and juvenile fireflies. Make sure to research which plants are native to Georgia!
Focus on more vegetation and less impervious surfaces. Meaning, less concrete, pavement, and brick and more greenery.
Reduce fertilizer use. Especially repeated lawn treatments for many years as this can have negative effects on the fireflies and their food.
Buffer bright and constant lights with trees.
Contribute to community science! Projects like the Atlanta Firefly Project help us better understand the threats that firefly species face as a result of urbanization and determine ways we can better protect these species in the future.
For more ways to protect fireflies in your yard check out the Xerces website: https://xerces.org/endangered-species/fireflies/how-you-can-help
If everyone works on taking care of their little corner, then all corners have a chance of being covered. Thank you to everyone that participated in the Atlanta Firefly Project Summer 2021 season and who dedicated their time to help us understand fireflies a little bit more. We hope you continue to stay involved in the project!
This summer, EcoReach is expanding the project beyond the Atlanta area, and as always, anyone is invited to join, so tell your family, friends, and neighbors! Visit the Get Involved page to sign up for our newsletter and the FAQ page for more information.
Resources:Firefly.org ‘Why are Fireflies Disappearing’ https://www.firefly.org/why-are-fireflies-disappearing.html
Atlanta Firefly Project Summer 2021 Results - Kelly Ridenhour, MS https://www.youtube.com/watch?v=zDDKrbdtAKI
Xerces.org ‘How You Can Help’ https://xerces.org/endangered-species/fireflies/how-you-can-help
