It’s not just humans who will be affected by the Great American Eclipse coming on Aug. 21: Expect animals to act strangely too.

Anecdotal evidence and a few scientific studies suggest that as the moon moves briefly between the sun and the Earth, causing a deep twilight to fall across the land, large swaths of the animal kingdom will alter their behavior.

Eclipse chasers say they have seen songbirds go quiet, large farm animals lie down, crickets start to chirp and chickens begin to roost.

Elise Ricard, public programs supervisor at the California Academy of Sciences in San Francisco, recalled the eerie silence that accompanied the start of a total eclipse early on a June morning in 2012.

“I was sitting on a beach with my back to the jungle, and if you know anything about jungles, they are not usually quiet,” she said. “But to suddenly hear all those noisy birds get quiet as the eclipse got close, that was a powerful sensory experience.”

Doug Duncan, director of the Fiske Planetarium at the University of Colorado, Boulder, has had a few strange run-ins with animals over his many years of eclipse chasing.

He saw a line of llamas gather together to see a total eclipse with him and his fellow astronomers in Bolivia.

When he was viewing a different eclipse from a boat near the Galapagos Islands, he saw dozens of whales and dolphins swim to the surface of the ocean five minutes before the eclipse began. They hung out there until five minutes after the eclipse, before returning to the watery depths, he recalled.

Totality – the time when the face of the sun is fully covered by the moon – only lasts a few minutes, but scientists say it is still capable of affecting animals who use light cues to help them decide what to do and when.

“Certain stimuli can overrule normal behavior without affecting an animal’s daily physiological rhythms,” said Joanna Chiu, who studies animal circadian clocks at the University of California, Davis.

To better understand how land animals react to a total eclipse, the California Academy of Sciences in San Francisco is launching Life Responds, a citizen science experiment using the mobile app iNaturalist.

And the best news? You don’t even need to be in the path of totality to participate.

“We want to see if animals are having a reaction at the 90 percent, 80 percent or even 75 percent mark,” said Ricard, who is helping spearhead the project.

Volunteers will be asked to make two observations on the day of the eclipse. The first should be made about 30 minutes before the point of maximum eclipse, and the second about five minutes before or after. “We know those two minutes of totality are precious, and you are going to want to be looking at the sky, not your phone,” Ricard said.

Observations of any animal behavior are welcome, Ricard said. She suggests looking to see if nocturnal animals begin to emerge, and her team is also interested in how domesticated dogs, farm animals and insects will react.

“We’ll take as many observations as we can,” Ricard said.

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