Yes, total solar eclipses can affect animal behavior

On April 8, 2024, a total solar eclipse will sweep across parts of the United States, Canada and Mexico, briefly plunging millions of people — and animals — into midday darkness.

Ahead of the rare celestial event, we’ve published two VERIFIED guides on how people can safely watch and photograph the solar eclipse.

After our stories were shared online, VERIFY reader T.M. asked if total solar eclipses can affect animal behavior.

THE QUESTION

Do total solar eclipses affect animal behavior?

THE SOURCES

• NASA
• Eclipse Soundscapes Project
• Oceana, a nonprofit ocean conservation organization
• Pacific University
• University of Alabama in Huntsville 
• University of Arkansas at Little Rock
• An article by Steve Portugal, Ph.D., comparative ecophysiologist and reader in animal biology and physiology at Royal Holloway University of London
• Science News, a bi-weekly magazine published by the Society for Science, a nonprofit dedicated to public engagement in scientific research and education
• Studies published on JSTOR, a digital library of academic journals, books and primary sources
• A study published in Animals, a peer-reviewed open-access scientific journal that covers all areas of animal biology
• A study published in the American Journal of Primatology, a monthly peer-reviewed scientific journal and the official journal of the American Society of Primatologists.
• A study published in Ethology, a monthly peer-reviewed scientific journal 
• A study published in the Journal of Fish Biology, a peer-reviewed journal publishing high-quality papers focusing on the biology of finfish in all aquatic ecosystems
• A study published in The Science of Nature, a monthly peer-reviewed scientific journal
• Zach Culumber, Ph.D., assistant professor at the Department of Biological Sciences at the University of Alabama in Huntsville 
• Raffaela Lesch, Ph.D., an assistant professor of biology at the University of Arkansas at Little Rock

THE ANSWER

Yes, total solar eclipses can affect animal behavior.

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WHAT WE FOUND

All of our sources agree that total solar eclipses can affect animal behavior. According to NASA, reports of atypical animal behaviors during total solar eclipses date back hundreds of years, but the space agency says “the effects of an eclipse on animal life are not fully understood.”

A total solar eclipse occurs when the moon passes between the sun and the Earth, completely blocking the face of the sun. People located in the path of totality – areas where the sun’s light is completely covered by the moon – will experience a total eclipse that will last between 3.5 and 4 minutes, according to NASA.

When totality happens on April 8, it will appear as if dusk has fallen, temperatures will drop and some stars will become visible. These changes can trick certain animals into altering their usual daytime behaviors, NASA says.

Nearly 100 years ago, American entomologist William M. Wheeler and a team of collaborators at the Boston Society of Natural History conducted a comprehensive study that noted a variety of changes in animal behaviors during a 1932 total solar eclipse that crossed parts of Maine, New Hampshire and Vermont.

NASA says the study included 498 personal observations from game wardens, naturalists and members of the general public. Several study participants reported that near totality, they heard crickets chirping and frogs croaking. Others observed gnats and mosquitos swarming, bees returning to their hives and chickens seeking roosting spots, according to a 2017 Science News article.

Zach Culumber, an assistant professor of biological sciences at the University of Alabama in Huntsville, said that animals instinctively transition into their nighttime activities as darkness falls during a total solar eclipse.

“Animals respond to environmental cues triggered by changes in light intensity,” Culumber said.

“This shift in light prompts adjustments in physiology, gene expression, and hormone levels, ultimately influencing behaviors like when to find cover for the night or when to come out to search for food,” he explained.

During a total solar eclipse in July 1991, researchers found that orb weaver spiders began to break down their webs, like they typically do at the end of the day. Another study conducted by researchers in Mexico during the same eclipse documented seeing some nocturnal bats briefly appear, “seemingly tricked by the sudden darkness,” comparative ecophysiologist Steve Portugal wrote in 2019.

During a total solar eclipse in June 2001, researchers with the Wildlife and Environment Zimbabwe group observed hippos leaving their rivers and heading toward their nocturnal feeding grounds on dry land, according to Portugal.

“Midway through their departure, the eclipse passed, daylight returned and the hippos aborted their efforts. The animals appeared agitated and stressed following the eclipse for the remainder of the day,” Portugal said.

Total solar eclipses can also affect marine animals, like fish and other organisms. Studies in the 1960s and 1970s found that small, light-sensitive crustaceans and zooplankton swam upward toward the dark during eclipses, according to Science News.

Researchers have also observed herring fish in Maine school on the water’s surface and reef fish in the Galapagos retreat to safety on the reef during eclipses, all behavior typically seen at twilight, Oceana, a nonprofit ocean conservation organization, said in a blog post.

Meanwhile, astronomer Doug Duncan, the former director of the Fiske Planetarium at the University of Colorado, Boulder, told the Los Angeles Times in 2017 that he saw dozens of whales and dolphins swim to the ocean’s surface about five minutes before an eclipse began while he was boating near the Galapagos Islands.

“They hung out there until five minutes after the eclipse, before returning to the watery depths,” Duncan said.

When it comes to domesticated animals, like cats and dogs, their behavior during a total solar eclipse depends on how they are kept at home, according to Raffaela Lesch, an assistant professor of biology at the University of Arkansas at Little Rock. 

“Most animals don’t panic or freak out with the sudden darkness,” Lesch said. “Indoor pets like cats probably won’t respond to the solar eclipse because they are used to having a lot of changes in their environment.”

“Animals who have more experience with the outdoors may experience a level of confusion. Dogs, for example, might be a little impatient and walk around and try to figure out if they should trust their internal clock or what they are perceiving outside,” Lesch added.

Lesch recommends giving your cat or dog a treat or a toy to help calm their nerves if they appear confused by the brief moment of darkness during the eclipse.

“It will be a very short time where it’s really dark. As long as we stay calm, the animals will be calm as well,” Lesch said.

On April 8, the NASA-funded Eclipse Soundscapes Project is enlisting the public’s help to collect all of the sights and sounds of the eclipse nearly 100 years after Wheeler’s eclipse study. Visit the Eclipse Soundscapes Project website for more details.