Overview: An Eclipse That Rewrote Birdsong
The total solar eclipse of April 2024 swept across North America, but humans weren’t the only ones listening for the drama in the sky. A new study reveals that at least 29 bird species altered their vocalizations before, during, and after the eclipse, with many birds spraying out a “false dawn chorus” as sunlight returned. The findings illuminate how quickly avian communication can respond to abrupt shifts in light and may offer clues about how birds navigate artificial lighting in modern landscapes.
How scientists used a crowd-powered approach
Researchers from Indiana University (IU) in Bloomington seized the moment to study light’s effect on wild birds in a way that would be impossible with traditional fieldwork alone. They launched a free smartphone app called SolarBird to crowdsource observations across North America. The idea was simple: engage the public as citizen scientists so that data could accumulate from many locations at once.
“Scientists can’t be in a thousand places at once,” said Liz Aguilar, an IU Ph.D. student who led the effort. “The app gets around this problem by leveraging the public as scientists. It also encourages people to look around and listen, adding to the show in the sky.”
The method: how citizen science mapped a national moment
App users reported what they observed in a 30-second window before, during, and after totality. They checked boxes detailing bird behaviors—whether a bird sang, flew, or changed its activity as light levels shifted. In Bloomington and across North America, participants contributed more than 1,700 user accounts and nearly 11,000 observations, providing a rich, multi-site picture of how birds responded to the eclipse.
To supplement the crowd data, researchers set up automated recorders around Bloomington to capture a broader spectrum of vocalizations. They then fed the audio into BirdNET, a neural-network system that powers widely used bird identification tools, to analyze close to 100,000 vocalizations. The combination of human observations and machine analysis helped ensure robust conclusions about species-specific responses.
What the data revealed: a spectrum of responses
Among the 52 species monitored, 29 showed detectable changes in vocal behavior around the event. Yet there was no single pattern. Some species fell silent during totality as if the dimmed light signaled a pause in daily routines, while others increased their singing as the sky brightened. The most striking pattern emerged after totality: 19 species appeared to produce a “false dawn chorus,” echoing typical morning songs even though it was not dawn.
Scientists stress that the timing and intensity of these vocal shifts varied by species, location, and the precise light conditions each bird experienced. For some birds, the rapid toggling of light might have mimicked dawn cues that normally trigger morning vocal activity. For others, the eclipse’s unusual lighting could have disrupted normal circadian rhythms in ways that prompted alternative singing behavior.
Implications and future directions
IU’s study has implications beyond birdwatching. Professor Kimberly Rosvall, an advisor to Aguilar, notes that the findings highlight how sensitive wildlife can be to artificial light and other rapid environmental changes. “It’s crazy that you can turn off the sun, even briefly, and birds’ physiology is so tuned to those changes that they act like it’s morning,” she said. This sensitivity may extend to urban environments where artificial lighting is pervasive, potentially affecting breeding, foraging, and communication in birds and other nocturnal or crepuscular creatures.
Beyond ecology, the SolarBird project demonstrates a powerful model for future science outreach. By turning the public into science contributors, researchers can gather timely data on dynamic natural events and engage communities in scientific literacy. As the eclipse season of 2024 fades from the sky, the collected data leaves a lasting record of how one brief moment of darkness could leave a chorus in the birds’ wake.
