Overview: A Rare Natural Experiment
The April 2024 total solar eclipse—often called the Great American Eclipse—briefly plunged much of central and eastern United States into near-night. The event offered scientists a rare, real‑world test of how birds respond when the light-dark cycle is suddenly interrupted. A team led by Liz Aguilar combined citizen science, machine learning, and a continent‑spanning natural experiment to reveal how swiftly and differently bird species react to abrupt changes in light.
The study’s backbone was SolarBird, a smartphone app that enabled observers to record bird behavior during the eclipse in real time. Alongside this public data stream, autonomous recording units in southern Indiana captured roughly 100,000 bird vocalizations before, during, and after totality. By applying BirdNET, an artificial intelligence tool that identifies bird species from calls, researchers could quantify vocal activity across a broad geographic sweep and a diverse set of species.
What the Data Showed
Among 52 species detected along the eclipse path, 29 exhibited significant changes in vocal behavior at some point during the event. The timing of the responses mattered. In the minutes before totality, 11 species increased singing as the sky darkened, perhaps attempting to maintain social contact or defend territory in unclear light. During the four minutes of darkness, 12 species reacted in varied ways: some reduced vocal activity, while others surged in call volume or shifted song structure.
After the Sun Reemerged: A False Dawn Chorus
Perhaps the most striking finding occurred after totality, when daylight returned. Seemingly a “false dawn,” the post‑eclipse period saw 19 species alter their songs. Barred owls emitted calls more frequently—up to fourfold over typical rates—while robins, known for their pre‑dawn songs, sang at about six times their usual rate. The researchers interpreted these patterns as a temporary reset of internal biological clocks, with birds behaving as if a new day had begun and adjusting their vocal activity accordingly.
Why This Matters: Timings of Light and Life
The work adds to a growing body of evidence that ambient light is a primary signal shaping daily and seasonal rhythms in birds. While prior eclipse studies offered scattered anecdotes, this research leverages a large‑scale, coordinated data collection to reveal robust, species‑specific responses. The eclipse did not affect all birds identically; some species showed pronounced changes, while others remained largely unchanged, underscoring the complexity of avian circadian systems and ecological needs.
Broader Implications: Light, Behavior, and Conservation
Beyond academic interest, understanding how birds respond to light disruption has practical conservation implications. Artificial lighting, urban development, and climate-driven shifts in habitat can create brief or chronic mismatches between birds’ internal clocks and their environment. The eclipse‑driven “reset” observed in this study offers a natural case study of resilience and vulnerability, illustrating how quickly birds can adapt—and how quickly they can be unsettled—by shifts in light regimes.
Methods and Tools: Citizen Science Meets AI
The SolarBird app empowered bird enthusiasts and researchers to contribute observations across thousands of kilometers. The integration with BirdNET enabled scalable, automated analyses of bird vocalizations, providing a more precise picture of vocal activity than might be possible with human listening alone. This combination of citizen science and machine learning represents a promising model for studying wildlife responses to rapid environmental changes in near real time.
Related Findings and Future Research
A companion Science Research Article (August 2025) expanded on light pollution’s influence on bird vocalizations, showing longer vocal episodes in brighter environments. Taken together, these studies suggest that both acute events like eclipses and chronic conditions such as artificial lighting can shape avian communication. Future work may explore whether similar resetting occurs in other taxa and how these behavioral shifts affect mating, territory, and survival outcomes over longer timescales.
Note: A Science podcast segment featuring Liz Aguilar and Kimberly Rosvall is available on Science.org after embargo lifts, offering additional context and expert perspectives on these findings.
