For many, an eclipse like the one on April 8 is a once-in-a-lifetime event. A total solar eclipse is a rare occurrence, and the one on Monday was special as it crossed the United States, meaning even if you aren’t in the path of totality, you will still be able to witness a partial solar eclipse.

Humans aren’t the only ones who are affected by an eclipse.

According to Andrew Farnsworth, a visiting scientist in the Center for Avian Population Studies at the Cornell University Lab of Ornithology, there have been studies and accounts of certain animals displaying unique behavior during an eclipse.

“We know that light is a very powerful stimulus for many animals. It entrains certain kinds of behaviors. That means it brings them about, it’s associated with them,” Farnsworth said in a media brief. “And so, what we often see during eclipses from the published accounts is that we may start to see nocturnal behavior, so for example, nighttime behaviors like crickets chirping, bats emerging, to start those sorts of behaviors. And stopping diurnal, or daytime behaviors, for example, birds going to roost or day flying insects landing.”

Joel M. Hamilton, executive director of the Alabama Gulf Coast Zoo, echoed those accounts.

“Depending on the level of the eclipse, the behavior of the animals changes,” Hamilton said. “In a full eclipse, nocturnal animals may become active and diurnal animals go to bed. Unless it is a low-level partial eclipse similar to a cloudy day, the animals often get quiet during the event. Most animals are affected primarily by light cycles, whether that is daily or annually. Thus, a total eclipse mimics dusk and oncoming nighttime for them but then a few minutes later the sun ‘gets’ up again!”

Animals

In a study conducted during the 2017 total solar eclipse at the Riverbanks Zoo and Garden in Columbia, South Carolina, a group of university researchers, members of zoo staff, zoo volunteers and university students’ data was documented that recorded the responses of 17 animals including mammals, birds and reptiles. Many of the animals showed behavioral responses to the eclipse, with the majority of the animals engaging in their established evening or nighttime behaviors. The next most frequent response was apparent anxiety, according to the study called “Total Eclipse of the Zoo: Animal Behavior during a Total Solar Eclipse.”

During the eclipse, approximately 75% of the observed species exhibited behavioral changes, with most engaging in evening or nighttime behaviors according to studies. Some animals such as giraffes, like the ones pictured here at the Alabama Gulf Coast Zoo, showed signs of anxiety during the eclipse. 

During the eclipse, approximately 75% of the observed species exhibited behavioral changes, including gorillas, giraffes, elephants, lorikeets, frogmouths, cockatoos, lapwings and the Komodo dragon.

Others exhibited anxiety. Gorillas approached their indoor enclosure during totality, giraffes huddled together away from visitors and flamingos congregated tightly with their heads held high. The study also noted unique behaviors, such as Galapagos tortoises mating just before totality and siamangs exhibiting vigorous brachiation, or arm swinging, and vocalizations.

There were some animals in the study, such as grizzly bears, sea lions and kookaburras, who were observed seemingly unaffected before and during the eclipse.

“When we compare that to what happens during a typical sunset, you’ll notice a very, very different pattern,” Farnsworth said. “So, what we’re seeing here is that the eclipse is strong enough to suppress that daytime diurnal activity of day flying insects and birds going to roost, but it’s not strong enough to initiate the kind of typical nocturnal behaviors we see at sunset, in particular during that August eclipse, for birds migrating or bats emerging.”

Similarly, Kyle Shepard, co-founder and director of public relations and outreach of Banding Coalition of the Americas, said organization members noticed birds react to the loss of light during an eclipse.

“Many migratory birds migrate at night just because it’s cooler, there is less chance of predators and they can more easily navigate over large stretches of water because they can use stars to navigate as well,” Shepard said. “So, it seems like during a solar eclipse, the change in light levels is what alters bird activity.”

So, during an eclipse, what do migratory birds do?

“Birds that are over land during migration during an eclipse will typically drop their activity level to almost nothing. It’s like they’ll just roost in place,” Shepard said. “And then after the eclipse is over, they’ll pick back up and continue to forage.”

However, Shepard said birds migrating and flying over long stretches of water cannot stop and continue their migration.

Shepard said birds who were not migrating would begin to roost as the sky darkened and resume their activity as the sky lightened again.

“For birds that are pelagic species that spend most of the time out at sea, they may move closer to land or go to roost slightly, a little bit before the eclipse actually starts to happen, and then they’ll roost for the few minutes during the eclipse and then the activity will pick back up like a normal day.”

Owners of cats and dogs have reported not seeing much of a change in their pets until eclipse totality, when some pets acted anxiously as if fire works were going off while other simply begged for their nightly dinner.

There have also been reports of crepuscular animals, such as deer, rabbits and coyotes, possibly showing more activity as they are active during the twilight hours between typical diurnal and nocturnal activity.

Insects

In another study conducted in 2017, “Foraging and homing behavior of honey bees (Apis mellifera) during a total solar eclipse,” researchers investigated how honeybees behave.

The study found that during the eclipse, honeybee foraging activity decreased significantly but did not halt entirely, contrary to previous beliefs. This suggests that ambient light levels during an eclipse can override honeybees’ internal circadian rhythms. Additionally, colonies with higher foraging needs decreased activity less than those with ample food, indicating that colony state influences individual foraging decisions.

In a second experiment, researchers observed that very few bees returned to their hives, while homing before the total eclipse accelerated, especially in drones. The study implied that honeybees may interpret decreasing light as deteriorating flight conditions, even though their homing abilities remain intact until complete darkness.

In other reports, scientists have reported that crickets will begin chirping during the eclipse as they normally would at nightfall. Similarly, fireflies have been observed blinking until the sky lightened again.

Studies have found that during the eclipse, honeybee foraging activity decreased but did not halt entirely, suggesting that ambient light levels during an eclipse can override honeybees’ internal circadian rhythms. 

Marine life

As for the effect an eclipse can have on marine life, there have been observed occurrences where zooplankton migrated up to below the euphotic zone, which is the layer closer to the surface that receives enough light for photosynthesis to occur, early in the morning preceding the eclipse. Bioluminescent algae were documented emitting their typical nocturnal glow in the middle of the afternoon.

In the April 16, 1906 edition of “Nature,” A. Mosely described, “During the partial solar eclipse observed in England on Aug. 30, 1905, I was taking a holiday and fishing in Slapton Ley (Devonshire). All the morning the sport had been indifferent, but as the eclipse neared its maximum, the fish suddenly became ravenous, and I took more in that hour than all the rest of the day. My experience was also that of all the other boats out there at the time. The explanation, I presume, would be that the fish imagined night was approaching, and therefore prepared for supper; and as every fisherman knows, the last half-hour, when dusk is gathering, is the time that fish are mostly on the feed and will readily take any bait.”

Monday’s eclipse allows scientists like Farnsworth to continue studying the effect eclipses have on animals.

“It’s a very opportune time because large numbers of birds are migrating and they are strongly motivated to get to areas where they’re going to be breeding, sort of rushing to get there if you will,” Farnsworth said. “So, the idea that there may be more motives for birds to migrate, we’re very interested to look at that from the perspective of are we going to see the initiation of that kind of nocturnal activity because birds are more motivated to migrate during this April eclipse as opposed to the August (2017) eclipse, when that motivation is not so strong.”

For people like Farnsworth and Shepard, the April eclipse offered a chance to study the affects the eclipse has on birds in more detail. 

“I will be using an audio recorder called an AudioMoth, and it’s basically a full spectrum recorder, and I will set it to record for the time of the eclipse a couple of days leading up to the eclipse,” Shepard said before the April eclipse. “Record during the eclipse and then record after the eclipse, and that way we should see a drop off in the amount of song activity and then though our general observation, a decrease in foraging or moving activity during the eclipse. ... It’s a very interesting phenomenon ... and one that’s not very well understood.”