When the moon creeps in front of the sun Monday, the siamong — a member of the gibbon family — at Riverbanks Zoo in Columbia will go berserk, hooting up a storm and chasing around its enclosure.
Or maybe the large primate will just get eerily quiet and settle down.
Truth is, nobody really knows.
Cats, dogs and other common domesticated pets might become a little confused during a total eclipse, but generally would be more spooked by an owner's over-the-top reaction than by the eclipse itself, animal groups agree.
"It's nothing special. They start acting like it is a setting sun," said veterinary behavior specialist Bonnie Beaver, who is a past president of the American Veterinary Medical Association.
But for wild animals, despite centuries of anecdotal — and often contradictory — observations, very little study has been done on their behaviors during an eclipse. That's why teams at the Columbia zoo will closely watch the siamong, along with 11 other species.
During past eclipses, observers have noted behaviors such as birds chirping or quieting as they would at dusk, to weirder things, such as dolphins and whales surfacing en masse.
Even the people who deal with wild animals day to day are curious about what's going to happen.
"It's possible we see very strange behaviors if the animals get anxious; it's really completely unknown," said Adam Hartstone-Rose, Riverbanks Zoo adjunct scientist. "That's what makes it exciting."
James Island naturalist Billy McCord said butterflies, dragonflies and most day-time active flying insects are known to seek shelter or resting spots on branches, twigs or on the underside of leaves when conditions get very cloudy during the daytime. It's part of their nightly roosting behavior, he said.
"I think this same response will probably occur during the eclipse," McCord said. "Some birds and other wildlife will likely exhibit behaviors similar to what they would do when dense clouds or storms move into their area."
The rare solar total eclipse will happen Monday over the United States, including the middle section of South Carolina. In the Charleston region, it will be visible beginning just after 2:40 p.m.
A number of organizations are offering apps for "citizen scientists" to record their animal observations. They include Life Responds at the California Academy of Sciences, and Record the Earth at Purdue University in Indiana. Both can be loaded onto a cell phone.
At the zoo, teams that include keepers who work with the animals regularly, will fan out to record the responses of the siamong, gorillas, elephants, giraffes, sea lions, grizzly bears, flamingos, a Galapagos tortoise, Komodo dragon and two types of birds: tawny frogmouths and lorikeets.
Meanwhile, surveys will be handed out to an expected 7,000 to 8,000 visitors to record what they notice among other animals, Hartstone-Rose said.
In the Lowcountry, no formal studies are planned among biologists for the U.S. Fish and Wildlife Service or S.C. Department of Natural Resources, but staff members expect biologists in the field will make their own observations.
Want a glimpse of what to expect? More than a century ago, a total eclipse crossed the western United States and witnesses put pen to paper.
"Animals perceived the ebbing of the light, and they responded as they normally would at close of day," wrote David Baron in American Eclipse, his history of that event.
"In Rawlins (Wyoming), owls emerged. Farther north in a Montana gold mining town all the cocks in the city began to crow lustily and in regular succession. Across the region, cows turned homeward and pigeons went home to roost. Grasshoppers folded their wings and fell to the ground," Baron said.