How animal behavior may change when the total solar eclipse darkens skies

— -- Animals across the country may react strangely on Monday as the first total solar eclipse to traverse the sky above the continental United States in decades takes place, experts say.

"In total solar eclipses, there are observations of animals going to sleep," Rick Schwartz, an animal behavior expert with the San Diego Zoo, told ABC News. "The animals take the visual cues of the light dimming, and the temperature cues."

"You hear the increase of bird calls and insects that you usually associate with nightfall," Schwartz added. "Farmers have said that the cows lay down on the field or the chickens go back into the coop."

Schwartz emphasized that reports of animals going berserk during solar eclipses is "anecdotal."

"The reality is that because of the infrequency of solar eclipses, and because when it does happen, it is usually not in the same place, it is very hard to have actual scientific findings," Schwartz said of animal behavior during solar eclipses. "There have been observations at other zoos that animals didn’t react, which is also something to be noted."

NASA has released a list of zoos across the country that are within the eclipse's path of totality and hosting special events on Aug. 21.

"Our animals are (we believe) completely unaware of the impending astronomical event," zookeepers at the Nashville Zoo in Tennesee wrote in a blogpost. "We are very curious to see how our animal collection will react to a false dusk, night and dawn taking place over the course of a few hours in the middle of the day."

The Nashville Zoo is inviting visitors to record their observations of animal behavior during the eclipse and is giving out free protective glasses to the first 5,000 guests on the day of the eclipse.

Schwartz told ABC News that as for house pets, their behavior is not likely to change, as "domestic animals that live with humans, their cues come from our behavior."

Meanwhile, in an attempt to gain more insight into animal behavior during an eclipse, the California Academy of Sciences has launched a nationwide citizen scientist project, calling on participants to closely monitor the behavior of an individual organism during the upcoming eclipse and record their observations using an app.

Schwartz said that the technology available to Americans now versus when the last total solar eclipse passed over the country may result in new findings.

"That is exciting to see what will come up, we might end up with a lot more data than we’ve had before," Schwartz said.

He also encouraged eclipse watchers to take a moment to observe the behavior of animals for themselves on Monday.

"I would say if you are going to be out looking at the eclipse, as exciting and interesting as it is to watch, take a second or two to look away from the eclipse and listen for the wild birds and wild animals, and see what it is like when the planet goes dark," he said. "What do you observe?"