What do plants and animals do during an eclipse?

Many accounts of solar eclipses include tales of animals behaving strangely: Birds fall silent. Bees return to the hive.


“There’s a lot of anecdotal evidence for how animals and even plants respond to totality,” when the moon completely blocks the sun, says Elise Ricard, spokesperson for an eclipse project called Life Responds at the California Academy of Sciences in San Francisco. “But [there’s] not a lot of hard science.”

Perhaps the earliest record came from a total eclipse in 1544 when “birds ceased singing.” Another in 1560 said “birds fell to the ground.” In the past century or so, scientists have tried to approach the question systematically.

The Boston Society of Natural History collected observations during a 1932 eclipse that crossed parts of Maine, New Hampshire and Vermont, marking what they believed was “the first comprehensive and scientifically conducted study of the behavior of animal life during a total eclipse.” Crickets chirped and frogs croaked, study volunteers reported. Gnats and mosquitoes swarmed (“our stockings attested to the bites, for they drew blood and never let up”). Bees returned to hives and chickens to roost.

TURNING IN Orb weaver spiders like this one have been observed taking down their webs during an eclipse, just like they do every night.
JUNKYARDSPARKLE/WIKIMEDIA COMMONS (CC0 1.0)
Studies in the ’60s and ’70s reported that small, light-sensitive crustaceans and zooplankton swam upward toward the dark during eclipses, similar to how the tiny animals behave at night. The sun’s disappearance prompted orb weaver spiders to take down their webs, an eclipse in 1991 revealed. And during an annular eclipse in 1984, when the moon blocked all but a ring of bright light, captive chimpanzees scaled a climbing structure and faced the blocked sun.

Those observations are tantalizing, but they were limited in scope. That could change with the coming eclipse. The ubiquity of smartphones means that crowdsourced research — particularly during the eclipse — can include more and better coordinated observations than ever before.

This year, the California Academy of Sciences is soliciting citizen scientists to record their observations of any animals they see using the academy’s iNaturalist app. The team there hopes to get more descriptions of more species covering a larger geographic area than during any previous eclipse.

“We’re looking for observations from anywhere in the continental United States,” whether citizen scientists are in the path of totality or not, Ricard says. She wonders how wildlife will react, even if they’re only experiencing a partial eclipse. “I’d be interested to know where the line is, what percentage of totality you see responses for.”







Citations
W. M. Wheeler et al. Observations on the behavior of animals during the total solar eclipse of August 31, 1932. Proceedings of the American Academy of Arts and Sciences. Vol. 70, March, 1935, p. 33. doi: 10.2307/20023118.

E. Kampa. Observations of a sonic-scattering layer during the total solar eclipse, 30 June, 1973. Deep-Sea Research. Vol. 22, 1975, p. 417.

G. Uetz et al. Behavior of colonial orb-weaving spiders during a solar eclipse. Ethology. Vol. 96, January 12, 1994, p. 24. doi: 10.1111/j.1439-0310.1994.tb00878.x.

J. Branch and D. Gust. Effect of solar eclipse on the behavior of a captive group of chimpanzees (Pan troglodytes). American Journal of Primatology. Vol. 11, 1986, p. 367. doi: 10.1002/ajp.1350110407.