During the April 8 total solar eclipse, plant and animal scientists will head to the field, not to look to the sky, but rather to witness the eclipse’s effects on living things.

The eclipse’s “path of totality,” where the moon’s shadow will completely cover the sun, will be about 120 miles wide, spanning 13 states from Texas to Maine. Much of it will cross rural America. Totality will last approximately four minutes, with around two and a half hours of partial eclipse before and after. In addition to darkness, total solar eclipses produce effects like variations in the spectrum of available light, fluctuation in temperature, and even changes in the earth’s magnetic field. Many species can detect and react to the changes and researchers want to be there to observe. 

Scientists aren’t necessarily sure what they will uncover. Angela Speck, director of Astronomy at the University of Missouri said, “It’s never really been studied systematically,” adding, “Is this an illumination thing? The amount of light they’re receiving goes down. Is that what it is? Is it a temperature effect? Is it all of that?”

There are independent studies on wildlife responses to eclipses. Researchers have confirmed that many animals react by eliciting nocturnal behavior. During the 2017 eclipse, researchers at the University of Oxford, England observed birds returned to their perches and bees flew back to their hives up to an hour before totality. The same year, researchers at the University of Tennessee noted certain animals ceased foraging, typical at nightfall.

Research also indicates the sudden shift from darkness back into light can confuse animals. Brian Lada of AccuWeather said, “As light suddenly returns, it [spurs] birds to look for food, as most…eat in the morning.” Other animals become agitated following an eclipse and remain so for the rest of the day. 

Temperature drops rather than variations in light may be more impactful. During the 2017 eclipse, researchers at the University of Missouri’s South Field Research Center recorded air temperature decreases around 6.4 °C. Nate Bickford, an animal researcher at the Oregon Institute of Technology said, “Solar eclipses actually mimic short, fast-moving storms,” with their darkening skies and dropping temperatures. He noted that birds and feral horses change the speed and direction of their travel during an eclipse, “probably taking cover, responding to the possibility of a storm.”

Unfortunately for agribusiness, existing eclipse-focused animal research has mainly been on creatures in the wild and in zoos. Few studies have concentrated on domesticated animals. Those that have are somewhat contradictory. Research on chickens suggests they perceive the onset of night and look for a place to roost. Conversely, studies on grazing dairy cattle indicated little to no behavioral change.

Inquiry is expanding beyond light and temperature. Studies like the Eclipse Soundscapes Project focus on multisensory data, including recording sounds like crickets that can trigger animal responses. The South Farm Research Center has added livestream cameras and microphones for studying bee activity.

While certain conclusions have been reached regarding animal behavior, less is understood about eclipse effects on plant physiology. Mirroring animal studies, much of the existing inquiry has focused on florae responses to light changes. Plants also have circadian rhythms, and it’s commonly believed they respond to an eclipse mimicking dusk. Farmer Daryl Obermeyer is skeptical - at least for soybeans. In an interview with the University of Nebraska’s Institute of Agriculture and Natural Resources, Obermeyer noted, “Soybeans are indeed sensitive to the 24-hour day/night cycle, but are only sensitive to night length, not day length.”

Vegetation also likely responds to temperature variation more than light changes. In 1995, researchers at the Division of Agricultural Meteorology at the University of Pune, India recorded sudden soil temperature drops from 0.4-0.5°C, with minimum temperatures during the eclipse lower than the day before or after. Work in 2017 by Tim Reinbott, director of the South Farm Research Center, is similar. He studied eclipse influences on drought-stressed row crops. They twist up their leaves during the day to prevent moisture loss and unfold them at night to intake carbon dioxide. “This shows that they have a circadian rhythm and were not fooled by the change in light from the eclipse. They only responded to the temperature change.”

Whether it’s temperature, light, or both, processes like photosynthesis and transpiration can be impacted. Multiple research studies indicated changes in both photosynthesis and transpiration that reduced a plant’s daily food production. Effects included drooping leaves, closing petals, sap flow reduction, and reduced water intake. During Asia’s 2009 eclipse, researchers at the University of Ryukyus, Okinawa recorded fluctuations in C02 uptake starting one hour before and lasting one hour after the event. In 2017, Daniel Beverly and a team of researchers at the University of Wyoming measured a 25 percent decrease in sap flow in certain trees. He suggested, “The rapid diminishing of incoming radiation during the solar eclipse is stressful and a shock, with a potential decrease in plant photosynthetic and gas exchange performance [which] may require minutes to hours to recover to pre-stress levels.” 

The good news for farmers: research also indicates that while plants are impacted by an eclipse, they don’t suffer long-term consequences. The reason is, that plants cope with sudden changes in sunlight and temperature on a daily basis. Any dips in photosynthesis or other processes will be short-lived, with no harmful after-effects.

Whether researchers find anything of long-term value for agribusiness is uncertain. Nevertheless, for the scientific community, eclipses are rare events and field research is the only viable option. Reinbott said, “The eclipse is so unique it would be a challenge to recreate the conditions in a lab or greenhouse. The full spectrum of the sun during [totality]; it’s hard to get that artificially.”