Eclipse Effects on Birds 

Our relationship with the moon has a rich and deep history. For time immemorial, cultures have connected to her cycles, orienting life around her phases and expressions. The moon’s presence transcends time and distance, and is, therefore,  something we who share the sky can all relate to. 

The moon’s illuminating and boundless quality makes us think of another orbital body that transcends boundaries, weaving together our stories and human experience- birds. 

And as it turns out, their interconnection has had deep impacts for science exploration and bird conservation. “Before the high-tech gadgets used to track bird migration today, there was moon-watching,” says BirdNote. This technique, innovated by ornithologist George Lowry in the 1940s, entailed pointing a telescope at the moon in order to see and count the silhouettes of migratory birds.

While technology has improved and we now use radar to track and predict bird migrations, we also have resources to more deeply consider the interrelatedness of earthly patterns. And, as time goes on, more studies are showing that the phase of the moon not only has an effect on us, but other species. 

As the moon affects the tides, cycles of fertility, why wouldn’t it affect “little pieces of weather?” as Dr. Kyle Horton, director of Birdcast, calls birds. 

In 2019, the Lund University of Sweden conducted a study to explore the connection between bird migrations and moon cycles. In the study, researchers used miniature data loggers to track 49 European Nightjars for a year. The data showed that these birds are more than twice as active on moonlit nights compared to dark nights. According to Lund University, it also showed that “the birds begin their autumn migration south about ten days after the full moon, and that the individuals synchronize the migration and fly off more or less at the same time.”

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While this study is one of the first of its kind to consider the impact of large patterns like planetary cycles on animal activity, the researchers do not deny that other species are likely deeply impacted. And, it turns out,  this is very true for another species of bird. In a similar study conducted by the same university, they attached tiny tracking devices to Black Swifts. They found that “Not only do Black Swifts stay aloft for up to eight months, but they ascend to almost three miles in the sky during moonlit nights.”

The data showed that during the day, the Swifts flew at low altitudes, while at night, they climbed to an average of 5,000 feet. This higher altitude spiked even higher- between 13,000 and 16,000 feet- on nights that were illuminated by a full moon. 

Black Swifts’ dependence on the moon was confirmed when on January 20th, 2020 there was a total lunar eclipse. Data from the trackers showed that as the eclipse effectively turned out the moonlight, the Black Swifts rapidly descended from the 13,000 feet altitude and then, when the moonlight ‘turned back on,’ they ascended once again to this extreme height! 

“It shows clearly that light has an immediate influence on their flight altitude,” says Anders Hedenström, an avian ecologist and lead author of the research. 

Another group of researchers  published a paper called “Moonlight Makes Owls More Chatty,” which discusses how there are plenty of studies on the effects of diurnal light and poses the question- why wouldn’t the quality of light at night affect the myriad of nocturnal species?

We must agree and, it seems, so does science. 

If you feel the rhythms of the moon, you are not alone. Owls are more communicative, Swifts fly what avid hikers call “14ers,” and even though radar now exists, you can still point a telescope on the moon and watch silhouettes of intrepid birds. So, as we make our way towards fall and a period of increased darkness, we know we will be taking the season to observe and envision the winged beings that paint flight across a vast, cosmic sky. We’ll be listening for echoing hoots while bathing in moon glow. Will you? 

https://www.audubon.org/news/a-lunar-eclipse-sheds-light-fascinating-behavior-birds

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