Imagine witnessing a midday sky turn pitch black, only for birds to burst into their morning songs as if the sun had just risen anew—sounds like something out of a sci-fi movie, right? But this bizarre phenomenon actually happened during the total solar eclipse on April 8, 2024, and it reveals fascinating secrets about how animals perceive time and light. Stick around, because what unfolded next challenges our understanding of nature's rhythms in ways that might just blow your mind.
The total solar eclipse that swept across North America on April 8, 2024, acted like a cosmic prank on the biological clocks of certain bird species, fooling them into thinking dawn had arrived, based on groundbreaking research just published.
This awe-inspiring event, where the moon slid perfectly between Earth and the sun, turned broad daylight into a brief spell of total darkness along a narrow strip stretching from Mazatlán in Mexico all the way to St. Johns in Newfoundland, Canada. You can learn more about the path of this eclipse and others at CNN's dedicated pages (https://www.cnn.com/2024/04/08/world/2024-total-solar-eclipse-path-scn and https://www.cnn.com/science/eclipses).
In the immediate aftermath and during the eclipse itself, researchers noted that 29 different bird species erupted into song, behaving as if a fresh day were kicking off. This key finding comes from a study released on Thursday in the prestigious journal Science (https://www.science.org/doi/10.1126/science.adx3025).
A huge boost to the research came from everyday people acting as citizen scientists scattered along the eclipse's route, which greatly expanded the study's reach and depth.
For experts studying animal behavior, this rare event was an ideal real-world test to observe how birds handle abrupt shifts in lighting—something that's nearly impossible to replicate in a controlled lab environment. Total solar eclipses like this one don't visit the same spot more than once every 300 to 400 years, per the study, meaning most wild birds had never encountered one before. This makes it a unique opportunity to study untamed animal responses.
Exploring how wildlife adapts to sudden natural occurrences, such as an eclipse, sheds light on their resilience to swift environmental shifts and supports conservation initiatives, explained Liz Aguilar, the lead author and a PhD candidate in the evolution, ecology, and behavior program at Indiana University Bloomington.
“Light exerts immense influence on bird actions, and even a short four-minute 'night' triggered many species to behave as if morning had come again,” Aguilar shared via email. “This highlights their extreme sensitivity to light changes, with direct ties to problems like light pollution and nighttime artificial lights.”
Just as we humans rely on sunlight and darkness to regulate our sleep and wake cycles, so do other creatures, Aguilar pointed out. For beginners wondering about this, think of it like your body's internal clock: a built-in rhythm that tells you when to eat, sleep, or be alert, all synced to the sun's patterns.
During the 2017 total solar eclipse, observers saw zoo animals reacting in interesting ways (https://www.cnn.com/2024/03/13/world/eclipse-zoo-animal-behavior-nasa-soundscapes-scn), with some birds heading back to their evening perches while night-loving animals stirred to life. But Aguilar's team focused on documenting wild birds specifically across vast areas.
The event timed perfectly with North America's lively spring season, when birds are busiest singing to woo partners, guard their turf, and navigate nighttime migrations. In spring, their vocalizations peak at dawn and dusk, making this period especially vibrant for birdwatchers.
So, what could this brief daytime blackout do to their finely tuned daily and seasonal patterns, which depend so heavily on light and dark cycles? Take Bloomington, Indiana, for example, where totality—a complete moon-sun block—lasted just four minutes and 15 seconds. It was like pressing a cosmic reset button mid-afternoon.
But here's where it gets controversial: Could this temporary trickery have longer-lasting effects on bird survival, or is it just a harmless hiccup in their routines? The team pondered how to blend public engagement with scientific observation, leading them to create a free app for smartphones, Aguilar recounted.
“Citizen scientists were crucial to our success,” she stated. “With the eclipse zipping across thousands of miles in mere hours, we couldn't cover every spot ourselves.”
The project gathered nearly 11,000 records from over 1,700 users of SolarBird, an app crafted by researchers from Indiana University Bloomington and Ohio Wesleyan University. This covered bird activity along 3,106 miles (5,000 kilometers) of the eclipse path, both before and after the event.
They also set up small, tissue-box-sized audio devices in southern Indiana to snag roughly 100,000 bird calls during the same windows.
SolarBird users had a straightforward task: Find a bird, watch it for at least a short while, and log behaviors like singing, flying, or feeding from a list of eight options.
“As we reviewed the data that evening, it was clear the community had pulled off something magical,” remarked Dr. Paul Macklin, an associate professor of intelligent systems engineering at Indiana University Bloomington’s Luddy School of Informatics, Computing, and Engineering.
The audio clips were then processed using BirdNET, an AI tool that identifies bird species by their vocalizations. Human experts on the team double-checked these identifications.
Out of 52 bird species that were active during the eclipse, 29 showed clear shifts in their singing patterns, according to the study's authors.
Birdsong during totality
Listen to birds vocalizing during the April 8, 2024 total solar eclipse in Indiana.
Source: Liz Aguilar/Indiana University
As darkness fell, 11 species ramped up their songs beyond normal levels. While some went quiet in the eclipse's shadow, others perked up.
But the most dramatic shift happened when the sun reappeared, sparking a “false dawn chorus” in 19 species—a phenomenon where birds sing as if greeting a new morning.
For example, barred owls hooted four times more frequently than usual. Robins, known for their unique pre-dawn melodies, sang six times their average rate.
For these birds, the returning light flipped their internal switches, essentially rebooting their biological clocks, Aguilar explained.
Birdsong after totality
Hear the birdsong roughly four minutes post-totality in Indiana.
Source: Liz Aguilar, Indiana University
“Birds welcome the dawn in diverse styles—some belt out loud, complex choruses, while others stay subdued,” Aguilar noted. “Our research showed that species with the most vigorous dawn songs were the most responsive to the eclipse's chaos.”
Although the study didn't track long-term consequences, the team suspects any enduring effects would be minor. Still, those moments of confusion might have diverted time from essential tasks like hunting for food, finding a mate, or protecting territory, Aguilar added.
Not every bird species reacted identically, and responses were most pronounced in the zone of total eclipse, where the moon fully obscured the sun.
“This variation makes sense because birds have different sensitivities to light shifts,” Aguilar said. “Each one has unique habits, energy demands, and senses, so they process environmental cues in their own way.”
In some cases, birds might have picked up on their neighbors' calm behavior, realizing the darkness wasn't a genuine night, she suggested.
Dr. Stefan Kahl, the developer of BirdNET at Cornell University's K. Lisa Yang Center for Conservation Bioacoustics, emphasized the importance of verifying AI detections, even though he wasn't part of this study. He has conducted related eclipse research (https://www.nature.com/articles/s41598-025-94901-6). “BirdNET can err, but those errors follow patterns, allowing us to detect vocal changes during an event like this,” he said. “From our work, it's clear not all birds react the same—and this study's authors agree—that's perfectly logical.”
Dr. Andrew Farnsworth, a visiting scientist at Cornell's Center for Avian Population Studies, who has examined bird behavior in the 2017 and 2024 eclipses, found these results consistent with his observations. He praised the innovative use of crowdsourced data across the continent.
“These insights are invaluable for grasping how animals sense and adapt to their surroundings, offering clues into how their behaviors develop, persist, and possibly evolve,” Farnsworth said.
And this is the part most people miss: Pinpointing which bird species are most affected by light changes could be vital as our planet grows brighter from more artificial lights everywhere.
A recent investigation (https://www.science.org/doi/10.1126/science.adv9472?adobe_mc=MCMID%3D41746065266817496851431942600181853447%7CMCORGID%3D242B6472541199F70A4C98A6%2540AdobeOrg%7CTS%3D1760105551) revealed that light pollution can throw off birds' timing signals, causing them to vocalize an extra hour nightly—especially those with bigger eyes or open nests. It can also confuse migrating birds, leading to deadly crashes into city skyscrapers (https://www.cnn.com/2023/10/10/us/dead-birds-chicago-building-scn-trnd).
Thankfully, a growing push to combat light pollution (https://www.cnn.com/science/light-pollution-dark-skies-c2e-spc) aims to lessen its toll on various wildlife.
“Identifying the most vulnerable species allows us to target conservation where it's most critical,” Aguilar concluded.
What do you think—does this eclipse reveal that animals are more adaptable to sudden changes than we realize, or does it underscore the hidden dangers of disrupting natural light cycles? Do you agree that light pollution is an underestimated threat, or perhaps an inevitable part of modern life that we can mitigate? Share your thoughts in the comments below—we'd love to hear your take! Sign up for CNN’s Wonder Theory science newsletter (https://www.cnn.com/newsletters/wonder-theory?source=nl-acq_article) to dive deeper into the wonders of the universe, from cutting-edge discoveries to mind-bending science. But is this just a quirky bird story, or a wake-up call for how human actions are messing with the natural world? Your opinion matters—jump in the discussion!
