How Do Animals React to a Total Solar Eclipse? Scientists Document Strange and Surprising Behaviors | Science

Carlyn Kranking

Assistant Editor, Science and Innovation

As a total solar eclipse darkened the sky during the afternoon of August 31, 1932, citizen scientist Joseph R. Burgess watched five hives of honeybees in Nantucket, Massachusetts.

At first, nothing seemed odd. The bees came and went in their usual numbers. But as darkness fell, “a great roar of wings ensued,” Burgess wrote. Soon, the air was thick with honeybees, all in a “great rush” to return to their hives—with so many trying to get in that the entrances became “blocked with bees.” But roughly 20 minutes after totality, the colonies seemed to return to their usual routines. “Just the sort of flight that occurs early in the morning,” Burgess wrote.

On that day, spurred by newspaper ads, a ragtag cohort of citizen scientists dotted the path of totality in a farming region of New England. Together, they recorded nearly 500 accounts of animal behavior and mailed them to a team of researchers led by William Morton Wheeler, an entomologist at Harvard University.

The crowdsourced bits of data were wide-ranging and often quirky. Mosquitoes—described by observers as “annoying” and “very vicious”—started biting in the darkness of totality. Nocturnal birds such as owls and whip-poor-wills began to call. Skunks came out to forage in the dark. An eastern garter snake had “evidently been feeding actively during the eclipse,” since it appeared to have a stomach full of food. And a woman told a citizen scientist that cockroaches infested her pantry after totality.

Each of these was just an anecdote—scientists can’t show that any one reaction was directly caused by the eclipse. And many creatures across several species didn’t seem to react at all. But during this year’s total solar eclipse on April 8, researchers will get another rare chance to explore how animals across the continent respond as they are plunged into a sudden, apparent “nighttime” in the middle of the day.

Ancient human civilizations saw eclipses as omens—and, often, ones with foreboding and terrifying implications. Today, eclipse viewers report profound feelings of awe and connection. But humans don’t witness eclipses alone—some might go outside with their dogs, or watch the spectacle alongside wild birds, crickets, frogs or ants.

“We ourselves are so impacted during an eclipse. Everybody I know who has been through a total eclipse has been really moved by it,” says Adam Hartstone-Rose, a biological scientist at North Carolina State University. Given how intensely our own human emotions are tied to such an event, he adds, “I think people are really interested in contemplating what must be going through the minds of the animals that they can experience this with.”

Despite his interest in the subject now, Hartstone-Rose initially had doubts when he led a study of animals at the Riverbanks Zoo in Columbia, South Carolina, during the solar eclipse in 2017.

“I was really skeptical. I didn’t think that animals were going to have a particularly strong reaction,” Hartstone-Rose says. After all, clouds and passing rainstorms regularly dim the sun’s light. “And animals don’t have a very strong reaction to that.”

Still, he stationed students across zoo exhibits of animals spanning 17 species and had them observe the creatures for two days before the eclipse and on the day of totality. To his surprise, about three-quarters of the species showed a measurable response—and, in a few cases, the animals did something completely unexpected.

The Galápagos tortoises, which are usually very sedentary, displayed one of those unusual behaviors: “During the peak of the eclipse, they actually started mating, which was remarkable,” Hartstone-Rose says. “That was bizarre.”

Meanwhile, the Komodo dragon had spent the two days prior to the eclipse sitting still as a statue. “It could have been a taxidermy animal as far as we could tell,” Hartstone-Rose says. “[It] didn’t move one inch,” even on the morning of the eclipse. But once the moon blocked out the sun’s rays, the reptile moved toward the door to its indoor enclosure, which was closed, then began running around the exhibit, “almost, like, climbing the walls,” until the sun reappeared.

Across the zoo, many other animals responded to the total eclipse, disproving Hartstone-Rose’s initial impression. Gorillas collectively approached their evening habitat. Flamingos gathered together, putting their young at the center of their huddle. Two cockatoos began touching beaks and preening each other. A sleeping tawny frogmouth—a nocturnal, “goofy little bird”—woke up and started foraging during totality as if it were nighttime, though the creatures usually just “try their best to look like a tree stump” during the day, says Hartstone-Rose.

Some of the animals didn’t react at all or didn’t seem fazed—one bear that had been lazing around simply lifted its head a moment, then returned to sleep. And even when creatures did react, especially when they showed signs of anxiety, the eclipse might not have been the only driver of that response: Increased visitor activity at the zoo could have unsettled them, for example.

But overall, the findings seemed clear: Many animals, like humans, appear to experience something when a total eclipse occurs.

This result was corroborated by amateur observations from across the country during the 2017 eclipse, as part of a project called Life Responds. Within and outside the path of totality, citizen scientists snapped pictures of organisms’ reactions to the event, then uploaded them to iNaturalist’s page for the project, organized by the California Academy of Sciences.

Countrywide, people noticed swallows and swifts flocking as darkness fell. Frogs and crickets, common elements of an evening soundscape, started to call, while diurnal cicadas stopped making noise. Ants appeared to slow down or stop moving, and even domestic chickens responded—hens gathered together and got quiet, while roosters crowed.

One observer in Idaho found a bat that seemed to have died during totality: “My guess is that it came out during the coolness and darkness of the eclipse then got too hot when the sun quickly came out.” Another person in Oklahoma recorded that a herd of bison did not appear to react.

A citizen scientist watched a yellow okra flower close during totality, just as it would at night—a favorite observation of Alison Young, co-director of the Center for Biodiversity and Community Science at the California Academy of Sciences and lead author of a paper describing the findings. The flower’s response was unexpected, she says in an email, since totality wasn’t very long.

With this year’s total solar eclipse less than a week away, the Life Responds team is eager to repeat the experiment—and researchers and citizen scientists alike are gearing up to collect a new round of animal observations. This eclipse will sweep across an even wider swath of the continent than the last one did, and its different path will allow for more varied data to be collected.

For one, totality will be nearly twice as long as it was seven years ago, which could have a stronger influence on animals, leading to more of a response. However, the April timing of this event could drive the opposite result, Young says.

“We may see less response overall for the areas of totality that are in northern latitudes, since there’s just less plant and animal activity there this time of year, compared to the 2017 eclipse that pretty much cut through the middle of the U.S., west to east, in the height of summer,” she adds.

Hartstone-Rose will be repeating the zoo research, this time at the Fort Worth Zoo in Texas. He’ll also collect crowdsourced reports of activity during the eclipse—from wild animals to pets and livestock. “One of the questions I’m really interested in is what level of totality triggers some of these behaviors,” he says. For instance, do animals still seem to react if the sun is only 90 or 95 percent covered?

Likewise, the Life Responds project team is making a few tweaks to its methods this time around. In addition to collecting submissions of photos, researchers are asking citizen scientists to write a description of the behavior they experienced and encouraging collection of sound recordings. This will better capture some reactions that aren’t necessarily photographable, such as an absence of animals or stopping of behavior.

These changes get at a fundamental truth about scientific observation that eclipses can reveal: Science is not done only through sight. And, similarly, eclipses are not just visual experiences.

“People are often asking people, ‘Where are you going to see the eclipse?’ ‘Where are you going to watch the eclipse?’ But eclipses are actually much more than that; they’re multi-sensory experiences,” says MaryKay Severino, education director at ARISA Lab. “You can feel temperature drops, you can feel excitement, you can listen to all of the changes around you.”

And when it comes to animal responses to this rare celestial event, many also seem to be felt and heard. That’s why the Eclipse Soundscapes Project, led by ARISA Lab and supported by NASA, aims to capture audio recordings and multi-sensory observations from hundreds of participants across the continent. People might make a note of a specific bird call they heard—or just that they heard birds singing—and describe what the weather felt like.

The team plans to make their dataset publicly available so that other scientists can use it to probe their own research questions. They hope to cast a wide net and gather as much input as they can, from a variety of environments—“truly everywhere,” as Severino says—even urban areas.

Afterward, other teams might use this information to study animal reactions based on bird calls or insect sounds. But the Eclipse Soundscapes team in particular is hoping to study the noises of crickets, since they are so widespread. In Wheeler’s study of the 1932 eclipse, lots of observers noted that crickets’ chirping intensified during totality—and this year’s observations could add understanding or nuance to that trend.

At the end of the day, however, total solar eclipses are rare. According to NASA, a total eclipse will pass over a given spot on Earth only once every 375 years, on average. If an individual animal happens to be in the path of totality on Monday, it’s probably never going to experience totality again in its lifetime. As a result, understanding how animals react to these phenomena simply doesn’t have an impact on everyday life.

But studying how creatures respond to totality does satisfy a distinct curiosity for eclipse viewers.

“There’s a fundamental thing about being a human where we want to answer questions about amazing things,” says Hartstone-Rose. “So that’s why this really matters.”