How a rare cosmic event reshaped bird behavior
When the April 2024 Great American Eclipse plunged midday into near-night across much of the central and eastern United States, it did more than dim the landscape. It provided scientists with an unprecedented, large-scale natural experiment to observe how quickly and dramatically birds respond to abrupt changes in light. In a study led by researchers including Liz Aguilar, the eclipse became a window into the daily and seasonal clocks that govern avian behavior and vocal activity.
The SolarBird project and a continent-wide data rush
Anticipating the event, Aguilar and colleagues launched SolarBird, a smartphone app that invited the public to log real-time observations of bird behavior during the eclipse. The citizen-science effort yielded nearly 10,000 observations along roughly 5,000 kilometers of the eclipse’s path, providing a diverse dataset that complemented controlled recordings. In parallel, autonomous recording units were deployed in southern Indiana to capture about 100,000 bird vocalizations before, during, and after totality. The recordings were analyzed with BirdNET, an artificial-intelligence system designed to identify bird species calls and quantify vocal activity with high precision.
The surprising tempo of responses across species
From the combined data, the researchers found that 52 species were detected in the study area, with 29 showing significant changes in vocal behavior at some stage of the event. The responses were not uniform across species, reflecting differing life histories and ecological niches. In the minutes leading up to totality, 11 species increased singing as the sky darkened, perhaps interpreting twilight cues as a cue to compact time or to reassert territory and social signaling before a closing of the day. During the four minutes of darkness, 12 species altered their vocal patterns—some fell silent, while others became unusually active.
A post-eclipse echo: the false dawn chorus
The most striking pattern emerged after the Sun reappeared. As daylight returned, 19 species shifted their songs, an effect the researchers likened to a “false dawn chorus”—birds seemingly treating the moment of solar return as if a fresh day had begun. Notably, barred owls increased their calls fourfold, and robins, renowned for pre-dawn song, sang at roughly six times their typical rate. The team interprets these flurries of vocal activity as a temporary reset of biological clocks, with birds recalibrating their internal schedules in response to the rapid light rebound.
Implications for understanding birds, light, and behavior
The eclipse study adds a concrete, multi-species demonstration that light acts as a powerful regulator of avian rhythms. It also showcases how citizen science and AI-powered analysis can work together to capture rapid behavioral shifts across large geographic scales. While the eclipse was a unique occasion, the researchers suggest parallels to other rapid light perturbations—cloud cover, artificial lighting, and urbanization—that similarly disrupt natural cycles. The work underscores the importance of light as an ecological driver and raises questions about how birds adapt to a world where daytime and nighttime cues are increasingly altered by human activity.
Broader context: light, noise, and birds in a changing world
Beyond the eclipse, related research has begun to map how light pollution can extend the vocal activity of birds, especially for species with certain visual and ecological traits. A 2025 Science article highlights that birds may sing roughly an hour longer in lit environments, with potential implications for energy budgets, mating dynamics, and predator–prey interactions during breeding. Together, these studies illustrate a broader theme: birds are finely tuned to the rhythms of light, and modern environmental changes can disrupt those rhythms in measurable ways.
What reporters can take away
The eclipse offered a rare natural experiment that revealed the speed and scope of avian responses to light disruption. For coverage, consider noting which species showed early- versus late-day vocal shifts, how the timing of light changes maps to behavioral peaks, and what the findings suggest about the resilience of bird communities to artificial light. An accompanying Science podcast segment with researchers provides additional context and can be cited for broader broadcast use, following standard attribution practices.
In sum, the April 2024 total solar eclipse did more than alter the sky; it briefly rewired avian clocks, prompting a chorus that rose, paused, and then reset as birds redefined the meaning of a new day.
