[Science] Nightjars time their epic migration flights using a lunar calendar – AI

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[Science] Nightjars time their epic migration flights using a lunar calendar – AI


By Jake Buehler Nightjars use the moon’s phases to time their long journeysDavid Tipling/Alamy The European nightjar, which migrates from northern Europe to sub-Saharan Africa, seems to synchronise its flying with phases of the moon. It is the first time an animal’s migration patterns have been shown to be associated with the lunar cycle. “Most birds migrate at night, therefore the effect of moonlight on migration has always been an open question,” says Cecilia Nilsson at Cornell University in New York. Until now, there was little evidence of a connection, though nightjars were a natural choice to look for one. The birds feed at night, snatching insects from the air. We already knew that they change their feeding habits based on the moon’s phase, gobbling more insects on bright, moonlit nights. Could nightjars also be scheduling their migration in a similar way? Advertisement To find out, Gabriel Norevik at Lund University in Sweden attached tracking devices to 39 European nightjars. Some of these devices measured the birds’ position using GPS, while others tracked their acceleration. This allowed Norevik and his team to record location over the year and flight activity levels night after night. Their results reveal a key role of the full moon in the nightjar’s itinerary, which consists of long night-time flights with daytime resting punctuated by much longer rests at stopover sites. On moonlit nights, the birds’ foraging during migration stopovers more than doubled. Read more: Climate change is forcing geese to give up pit stops when they migrate Then, as the moon wanes, increasing numbers of nightjars embark on flights along their migration route, peaking at around 11 days after a full moon. Sometimes, all of the tracked birds would migrate simultaneously at this time in a great pulse. The team also found that the birds concentrate their feeding activity at dawn and dusk on most nights, only foraging through the night when there is plenty of moonlight. Norevik says he and his team were astounded by how well the activity pattern of the birds followed the cycles of the moon. This is the first time moon phase has been identified as a regulator of migration schedule. Nilsson says these findings raise questions about the impact of artificial lights on any migrating birds relying on the lunar cycle. Light pollution is thought to be harmful to birds, but if the light of the full moon increases their foraging success, maybe artificial lighting could help them in that regard, acting as a bright, alternative moon. “Worldwide, animals migrate by the billions every year and our findings may improve our understanding of how and when many of them time their movements,” says Norevik. Journal reference: PLoS Biology, DOI: 10.1371/journal.pbio.3000456 More on these topics: animals birds

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