Darkness at noon: What the 2024 eclipse revealed about bird behavior

On April 8, 2024, millions across North America paused to watch a rare and awe-inspiring celestial event. A group of scientists was there, prepared to track bird behavior during the total solar eclipse.

The researchers discovered that birds fell unusually quiet. This behavior, however, only occurred in areas where the sun was almost completely obscured.

The research was led by scientists from Loggerhead Instruments and the K. Lisa Yang Center for Conservation Bioacoustics at the Cornell Lab of Ornithology.

The experts analyzed data from 344 Haikubox devices (small, community-powered acoustic monitors spread across the continent). This was the first large-scale study to use the Haikubox network for scientific analysis.

A neural network detected changes in bird vocalizations while controlling for human interference.

Did birds go silent?

“Anecdotal evidence has long suggested that birds fall silent or exhibit nighttime behaviors during a total solar eclipse,” said Dr. David Mann, lead author of the study and researcher at Loggerhead Instruments.

“Our study shows that, on average, birds do get quiet during and just after totality, but we also learned that this behavior is strongly linked to the degree of darkness experienced.”

The findings confirmed that birds generally reduced their vocal activity during totality – but only in areas where the eclipse brought more than 99% obscuration. This threshold made all the difference.

Bird reactions to the eclipse varied

Interestingly, not all birds responded the same way. Even birds of the same species behaved differently at different locations.

For example, black-capped chickadees in New York remained silent well after totality. The same birds in Vermont became more vocal during and just after the darkest moment.

Other examples were just as varied. Some American robins in Kentucky continued singing through the eclipse.

In contrast, pine siskins in Maine fell completely silent. These site-to-site variations left researchers with more questions than answers.

“The variability in bird responses and site differences was fascinating,” said Dr. Mann. “We really don’t know why birds had such different responses to the total darkness during the eclipse.”

“Despite examining factors like temperature, cloud cover, and wind speed, we found no significant relationship with changes in vocalization rates.”

“This strongly suggests that the sudden total darkness and associated changes in wind and temperature were the primary drivers of the observed behavioral shifts.”

Keeping human noise out of the data

One key feature of the study was its effort to isolate the human factor. Haikubox data that may have been influenced by people nearby was adjusted accordingly.

This helped ensure the birds’ behavior was truly in response to the eclipse and not to excited human activity.

“Our first, quick look at Haikubox data just a few hours after the eclipse showed a large dip in bird vocalizations around the time of peak totality,” said Dr. Mann.

“When we dove deeper into the data and removed any sites where humans may have influenced the birds’ behaviors, we found a much more complicated story. People were pretty excited about the total solar eclipse, and their celebrations likely affected the birds’ reactions.”

Monitoring nature using sound

The Haikubox platform is built on the idea that everyday people can help monitor the natural world using sound.

Each device records local bird vocalizations and uploads them to a central database. It’s a non-intrusive way to gather wildlife behavior data at scale, and it doesn’t require a team of observers in the field.

“In a time when technology often pulls us away from the natural world, Haikubox does the opposite – it fosters a deeper connection to it. By combining AI technology with a love for the environment, Haikubox helps people engage with nature in a modern and educational way,” noted Dr. Mann.

This passive acoustic monitoring allows scientists to study how animals respond to natural events across large areas – without disrupting them.

Learning from bird behavior

Beyond eclipses, the study may have broader implications for understanding how birds react to sudden changes in light.

“Our findings can inform future research on the impacts of light pollution and sudden changes in light levels on bird behavior,” noted Dr. Mann.

“Furthermore, it proves that when we combine the power of community science with clever technology, we can learn amazing things about wildlife without disturbing them, which may inform future continental-scale studies.”

The researchers hope this will inspire more people to get involved in community science. More participants also means expanding the listening network.

“Passive acoustic monitoring is a terrific tool for gathering data about animal behavior, and regular folks play an important role in widening our listening network,” said Dr. Mann.

“Putting a Haikubox in your yard helps us add to the already 1 billion acoustic recordings we’ve gathered. Our community is enabling tomorrow’s scientific discoveries.”

The full study was published in the journal Scientific Reports.

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