Surprising ways animals react to solar eclipses

For a few precious minutes on April 8, darkness will descend across North America as a historic total solar eclipse crosses parts of the United States, Canada, and Mexico.

Millions of people already live under the path of totality, and millions more are estimated make the trek to see the moon blot out the sun. Many will likely experience the extreme psychological responses that this awe-inspiring phenomenon tends to provoke in humans. 

But according to biologists and long-time eclipse chasers, humans won’t be the only ones reacting to the dramatic changes in the sky.

During a total eclipse, the sky darkens to twilight levels and air temperatures drop. Over the centuries, people who have witnessed these effects have also noted that a variety of animals seem to change their behaviors in response.

What happens when day turns to night

Reports of unusual animal reactions to solar eclipses date back centuries. One of the earliest stories comes from Italian monk Ristoro d'Arezzo, who described what happened during a total eclipse on June 3, 1239.

As the sun disappeared and the sky turned dark, “all the animals and birds were terrified; and the wild beasts could easily be caught,” he wrote.

(What exactly is a solar eclipse? Here's what to know.)

During an eclipse seen in Portugal on August 21, 1560, astronomer Christoph Clavius wrote that during totality, “stars appeared in the sky and (marvellous to behold) the birds fell down from the sky to the ground in terror of such horrid darkness.”

While it’s hard to confirm such colorful anecdotes from history, modern astronomers and eclipse chasers have also reported wild and domestic animals noticeably reacting to eclipses: Dairy cows return to the barn, crickets begin chirping, birds either go to roost or become more active, and whales breach in the seas.

Veteran eclipse-chaser Peter den Hartog traveled to Hungary in 1999 to experience totality, and he remembers seeing various species of birds and bats suddenly appear during totality.

“[Was it because of] the light intensity, or the flies and mosquitoes that came out … I'm not sure, but I‘ve definitely experienced more activity during eclipses,” Hartog says.

Eclipse-chaser and author Dave Balch was in Kona, Hawaii, for the 1991 total eclipse and noticed excited activity among the birds along the pier during the partial phases before and after totality.

“We could hardly hear each other talk! Then came totality—not a sound. It was deathly quiet. The difference between the noise levels before and during totality was stunning.”

(See 100 years of eclipse-chasing captured in quirky pictures.)

And eclipse-chaser Tora Greve was on an expedition to Zambia in 2001 when she noticed that, just as the sun disappeared, frogs began making sounds and raptors stopped circling, possibly due to the change in thermals as the air cooled.

Around the water hole where she was standing, she says, giraffes “started running about during the whole totality. When the sun came back, they stopped and began grazing the trees again.”

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How scientists study animals in an eclipse

Collecting scientifically meaningful data on animal reactions to total solar eclipses is tough business. The paths of eclipses are scattered around the world, and many are visible only from remote regions. That makes it hard to obtain anything more than a few data points per event.

“If you really want to study behavior in a comprehensive way, you have to spend a lot of time in the field observing and have rigorous protocols in place,” says ecologist Rebecca Johnson at the California Academy of Sciences.

“If you are an animal behavior ecologist setting up to just study effects of solar eclipses, it can be near impossible.”

To improve the scientific record, Johnson helped create the Life Responds project, which runs on a dedicated smartphone app called iNaturalist. Her team of biologists and astronomers used the app to collect data from the millions of people who witnessed the total eclipse that occurred in 2017—and they are continuing it again this year.

“We created this project that very simply asks people wherever they are—whether they are under totality or partial eclipse—to spend some time outside looking at animals and observing their behavior before, during, and after the eclipse,” Johnson told National Geographic in 2017.

In 2024, NASA launched its own citizen science project, Eclipse Soundscapes, which is focused on learning how crickets respond to the eclipse. Anyone can participate by recording data, analyzing audio, or submitting their own observations. (Find out how you can take part.)

What’s the best way to observe animal behavior?

People who want to take part in these citizen science opportunities should scout out in advance where they will be watching the eclipse and think about which animals will be around them. For instance, if you happen to be in a suburban backyard or city park, you may be best able to report on urban invertebrates such as ants and spiders.

Anecdotal evidence suggests that orb-weaving spiders destroy their webs during an eclipse, so Johnson recommends finding a web to watch.

(How to watch a solar eclipse safely.)

“That might be something particularly easy for people to observe,” she says, “because [spiders] don’t move very far like flying birds, and so there is a higher likelihood of recording slower invertebrate behavior.”

The hope is to create a meaningful clearinghouse for animal behavior during eclipses that scientists can use to advance their research.

“The collection of observations and looking for patterns is where science begins, and we hope to bring scientists to the data to spur their research moving forward,” Johnson said in 2017.

“Hopefully we’ll end up documenting something that no one has ever seen before.”