Sunday, August 13, 2017
As humans prepare in rapt anticipation for the "Great American Eclipse" on Aug. 21, they should know that animals are likely to act strangely that day.
Anecdotal evidence and a few scientific studies suggest that as the moon moves briefly between the sun and Earth, causing a deep twilight across the land, many species in the animal kingdom will alter their behavior.
Eclipse chasers say that on previous occasions they have seen songbirds go quiet, large farm animals lie down, crickets start to chirp and chickens go 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.
She was abroad when it occurred.
"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."
And, Doug Duncan, director of the Fiske Planetarium at the University of Colorado, Boulder, has had a few strange encounters with animals over his many years of eclipse chasing.
In Bolivia, some llamas gathered together to watch a total eclipse with him and his fellow astronomers.
When he was viewing an eclipse from a boat near the Galapagos Islands, dozens of whales and dolphins swam to the surface of the ocean 5 minutes before the eclipse began. They hung out there until 5 minutes after the eclipse, then returned to the watery depths, he said.
Totality -- the time when the face of the sun is fully covered by the moon -- lasts only about 2 minutes, but scientists say it affects 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. "It is not surprising that the eclipse will temporarily affect animal behavior, but it is unlikely to affect their internal clock or their behavior in the long run."
In Ohio, University of Toledo biology professor Elliot Tramer said that during a 2008 total eclipse on the northern coast of Venezuela he observed how seabirds reacted.
Brown pelicans and frigatebirds that had been foraging over the water before the eclipse left the bay 13 minutes before totality and didn't return until 12 minutes after the sun fully reappeared.
Fish can also be affected by an eclipse. In a study published in the Journal of Fish Biology in 1998, a team of researchers found that fish responded to the changes in light.
The researchers observed reef fish during a total eclipse over Pinta island in the Galapagos and found that daytime fish sought shelter in the reef during totality, while nocturnal fish were more likely to leave the cover of their daytime shelters.
And yet another study -- this one in Veracruz, Mexico -- found that some orb-weaver spiders start to dismantle their webs during totality and then rebuild them when the sun returns.
But scientists say there is always more to learn, and some of them have set up experiments to document animal behavior during this month's eclipse.
Jonathan Fram, an assistant professor at Oregon State University, plans to use a series of bio-acoustic sonars to see whether zooplankton in the path of totality will rise in the water column as the sun is obscured by the moon.
Spanning the ocean, an enormous number of animals hide in the deep, dark waters during the day, and swim upward at night to take advantage of the food generated in the sunlit part of the ocean.
"It's the biggest migration on the planet, and most of us don't even know it is happening," said Kelly Benoit-Bird, a senior scientist at the Monterey Bay Aquarium Research Institute, who is not involved with Fram's study.
Scientists have known for decades that changes in light can affect these animals' migration patterns. For example, most of the deep-water migrants won't swim as close to the surface as usual when there's a full moon. A total eclipse provides an ideal natural experiment to help researchers learn how important light cues are to different creatures, Benoit-Bird said.
Fram, who works on a project known as the Ocean Observatories Initiative, will be able to get data from six bio-acoustic sonars off the U.S. Northwest coast -- three that are directly in the path of totality and three that are not. That should allow researchers to see how much the sun has to dim to affect changes in the zooplankton's movements.
To better understand how land animals react in a total eclipse, the California Academy of Sciences in San Francisco is launching Life Responds, a citizen science experiment that will use the mobile app iNaturalist.
And people don't have to be in the path of totality to participate in it.
"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 5 minutes before or after.
"We know those 2 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 for changes in squirrel behavior (since squirrels are generally abundant) or perhaps looking to see if nocturnal animals like bats or owls begin to emerge as the moon covers the sun. Her team is also interested in how people's dogs and farm animals react, as well as how insect behavior changes.
"We have no idea how many observations we are going to get, but we'll take as many as we can," Ricard said.
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