This article is part of a special report on the total solar eclipse that will be visible from parts of the U.S., Mexico and Canada on April 8, 2024.
Ashleigh Papp: This spring—on April 8, 2024, to be exact—our moon will pass between Earth and the sun. For a small window of time during the day, the sun will go dark, temperatures will drop, and it will literally look like the middle of the night.
And then, after a few minutes of midday darkness, known as “totality,” our sun will reappear as the moon continues on its path and the day returns to normal.
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This event, a total solar eclipse, won't be visible to everyone. But it will be seen by those along the path of totality—which in the U.S. will bend from Texas all the way up to Maine.
If the sky is clear, you have a good chance of experiencing a natural phenomenon that, for some, happens only once in a lifetime.
But what about other living creatures who don’t know what an eclipse is?
[CLIP: Dog barking]
I’m talking, of course, about our four-legged friends, our pets and even wild animals. What happens to nonhuman living creatures during an eclipse, when they can’t grasp our well-researched and science-based understanding of the phenomenon, no matter how well we try to explain it to them?
For Scientific American’s Science, Quickly, I’m Ashleigh Papp.
[CLIP: Cat meowing]
Before we humans understood that a solar eclipse involves an orbiting mass, the moon, passing between our planet and the sun, ancient civilizations came up with all sorts of stories to help explain this extraordinary phenomenon. The word “eclipse” actually comes from the Greek word for “abandonment,” because ancient Greeks thought that a solar eclipse was the result of their gods being angry with them and that untold misery was in store when the sun abandoned the Earth.
But I wanted to understand how animals might interpret this sudden change in their world. So I spoke to Liz Aguilar, a behavioral ecology researcher at Indiana University in Bloomington.
She studies how the connection between the external environment triggers a chemical or hormonal response in an animal. Basically, she traces animal behavior backward.
One of these feedback systems that we’re all familiar with and that comes into play during an eclipse is our circadian rhythm. It’s controlled by an internal biological clock, which, for nearly all humans and other mammals, is actually a structure in the center of our brain. It helps us regulate our physiological and behavioral processes over a 24-hour period.
Liz Aguilar: With these circadian rhythms, these internal clocks, light is the primary factor contributing to optimizing that rhythm. This light being received by the photoreceptors in our eyes, going through neural processing in the brain, would control for that feedback of light information.
Papp: This rhythm cues diurnal animals, most humans included, to go to sleep when the sun sets and vice-versa for our nocturnal friends.
That means that when the eclipse happens, for those on its viewing path, your pets at home might act like they do when they go to bed at the end of the day.
Aguilar: One of the things I might expect is, especially the dogs outside, you know, watching the eclipse with its owner, we’re going to have that diminishing light. So photoreceptors are going to be sending signals that [are] you know, receiving less light, so we know it’s getting darker, signaling pathways that would release any hormones related to, like, that normal sleep-wake cycle.
Papp: And with this eclipse, when the moon covers up the sun, temperatures are expected to drop by about 10 degrees Fahrenheit, which will likely cause changes in atmospheric pressure. That, in addition to the unexpected darkness, may cause your outdoor pets to feel like a storm is approaching and result in a fearful or anxious-like response.
And what’s interesting about eclipse behavior is that it’s a quick transition to night and then, in just a few minutes, a return to day. So for those with chickens, they might head into their coop as if it were night and then come back out once the eclipse is complete. Or you might hear a bird’s beautiful song at an unusual time.
Aguilar: There are some indications of, you know, what's called a new dawn chorus, where once the light comes...the sun is back up, will birds act like it’s a new day, you know, “It’s morning again,” and do those morning vocalizations?
Papp: Our reptile and amphibian friends, pets like lizards, tortoises and frogs, on the other hand, usually have their own electric heating and light lamps. So they’re not likely to show much of a behavioral change.
Beyond our house pets, animals that spend more time outside are likely to show an even more dramatic response to an eclipse. Take, for example, a distant relative of your pet lizard, the Komodo dragon.
Adam Hartstone-Rose: So Komodo dragons are super cool. They’re the biggest of all of the lizards. They look, like, ancient, you know, and they’re really scary. It turns out they’re venomous. And they eat carcasses. I mean, they’re, they’re super creepy animals.
Papp: That’s Adam Hartstone-Rose. He’s a biology professor at North Carolina State University. And in 2017, he was working part-time at a zoo in South Carolina, doing some research. So when that part of the country was on the path of totality for a solar eclipse, he and his colleagues, including members of the zoo’s staff, decided to observe their behavior during the eclipse.
Hartstone-Rose: And the Komodo dragon literally did not move one inch on the Saturday or the Sunday leading up to the eclipse, which was on the Monday. And then, during the eclipse, all of a sudden, it started, like, moving slowly. And then it started scrambling around and really ran all around its enclosure, including, it ran to the part of the enclosure where it’s let back in in the evening. So it reacted. It had this strong reaction, like it was anxious, but it also basically went to where it thought it needed to go for when it became nighttime.
Papp: The zoo team staked out 17 animal species in total, ranging from primates and reptiles to bears and birds. They observed their behavior for two days before the total solar eclipse and then during that eclipse, which, in this part of South Carolina, lasted for two and a half minutes in the afternoon.
Hartstone-Rose: I thought that it was going to be, like, relatively boring. I didn’t think that the animals were going to have a very strong reaction to the eclipse. But it was just such a cool thing to do....And, like, actually, it turned out amazing. And, like, animals reacted way more, way more strongly than I thought they would.
Papp: There isn't a lot of published research out there about animal behavior during an eclipse. A few have focused on a single species or animal, but the only other study that spanned multiple species was nearly 100 years ago. It involved observations from people who wrote in to a local newspaper in New England about how their animals reacted. Another story that Adam had read about was of a group of giraffes in Africa that started galloping during an eclipse.
Hartstone-Rose: And giraffes very seldom gallop, like, if there's like a predator around or something...but they’re really gangly, and if they fall, they will, like, die, because, you know, they’re kind of delicate animals for their size. And so I thought this was nonsense....But I stationed a student to watch the giraffe during 2017. And in fact, they did it. So most of them moved, like, kind of over to where they were supposed to be left at night. But a couple of them actually, like, kind of lost it and went…running around the enclosure, in ways that it actually almost seems dangerous, like, they seemed almost, like, out of control, like they were very anxious by what was going on.
Papp: All in all, his colleagues found that three quarters of the animals they observed showed a change in behavior during the eclipse. About half took the dusk-to-dark cue as, “Okay, it’s nighttime,” and moved toward their night house. But some demonstrated a behavior that suggested anxiety. They were thrown off and knew something was going on.
Hartstone-Rose: So Galapagos tortoises, also not a very energetic species. During the peak of the eclipse, the tortoises started breeding, which was crazy. So, I don’t know if eclipses have that effect on a lot of animals, but we’re going to be watching...actually, other species of tortoises during this upcoming eclipse and seeing if other species also start this breeding activity.
Papp: After the surprises that came out of his 2017 publication, Adam is gearing up to take a team of student scientists to a zoo in Texas. They're going to watch the same species for repeat behaviors and expand their efforts to see what other wild things happen when the sun goes dark for a few minutes during the day.
Hartstone-Rose: I have become a junkie, like, so I thought the eclipse was going to be cool. And I also thought that people…who chased eclipses around the world were kind of foolish— until I experienced my first eclipse. And it was amazing. And now I’m envious of people who, like, get on airplanes and go hunting for every eclipse possible.
Papp: Watching an eclipse and observing how it affects an animal's behavior can lead us to ponder some of the bigger, more fundamental questions of life, whether that means watching our pet in the backyard or something more wild. When the moon crosses in front of the sun, and our world goes dark in April, we will be reminded of how our being, our Earth and science are just plain awesome.
For Science, Quickly, I’m Ashleigh Papp.
Science, Quickly is produced by Jeff DelViscio and Timmy Broderick. Editing is by Elah Feder and Alexa Lim. Sound design is by Dominic Smith. Subscribe to Science, Quickly wherever you get your podcast, and head to ScientificAmerican.com for up-to-date and in-depth science news.
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