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보름달 뜨면 4천m 고공으로 치솟는 칼새의 비밀

[애니멀피플]
Flying insects like moths are considered to be hunting … During a full lunar eclipse, immediate reaction

American blackbirds, like Eurasian swordfish, spend most of their lives hunting insects in the air. Credit to Jacques Pollen.

Swordfish spend most of their lives in the air, eating, resting, and sleeping, except during the breeding season. The bird was found to change altitude in response to moonlight and rise up to 4000 m above the full moon. Andrews Haydenstrom, a professor at the University of Lund in Sweden, and others have published a paper in the latest issue of the scientific journal Current Biology. The tendency to climb to extreme heights according to the moonlight.

A blackbird nests in Idaho, North America.  It mainly breeds behind waterfalls or on rocks.  Is a weak item.  Terry Gray, courtesy of Wikimedia Commons

A blackbird nests in Idaho, North America. It mainly breeds behind waterfalls or on rocks. Is a weak item. Terry Gray, courtesy of Wikimedia Commons

Researchers have captured seven blackbirds nesting behind Zapata Falls at 2,890 meters above sea level in Colorado, USA, and fitted a wireless tracking device that can detect changes in light, acceleration and altitude. Like the Eurasian swordfish, the swordfish here live mainly in the air, except when they lay their eggs and raise their young for three months. Blackbirds breed in the Rocky Mountains and winters in Central and South America, such as the Amazon. “Except for rare and very short landings, they lived in the air for an average of 258 days,” the researchers found.

A study using a small wireless tracking device has revealed that Eurasian swordfish spend up to 10 months a year in the air except during the breeding season and roam the streets of the Korean Peninsula for a day (‘Air-fueled’ Sword bird that flies 8,000 km in 9 days). The researchers discovered an unexpected fact while compiling the flight log data of the Black Sword bird. Professor Haydenstrom, the lead author, said, “It’s amazing that the Sword flew so high above the moon.” This is a university press releaseThe bird flew hundreds of meters during the day, but rose to an altitude of 2000 to 4000 meters on a full moon night. The highest-flying swordfish recorded 4400 meters, and the average height of an overnight flight was 2741 meters. The average height on a full moon day is 497 m.

Researcher attaches a small wireless tracking device to a black sword bird trapped in a bird's net from a cliff behind a waterfall.  Credit to Mardi Jordan Sapathi.

Researcher attaches a small wireless tracking device to a black sword bird trapped in a bird’s net from a cliff behind a waterfall. Credit to Mardi Jordan Sapathi.

Why do sword birds fly in the sky on a bright moonlit night? The researchers argued that “the altitude is much higher than when the moonlight is weak, so this is not an act of avoiding poachers, but of chasing prey and climbing upwards.” In fact, numerous flying insects have been reported to be active during the full moon. In the United States, insects were hung from planes to collect insects at an altitude of 4,500 m, and in Australia, moths were found migrating at an altitude of 2,900 m. Insects migrating at an altitude of 2400 meters were also caught on the radar. The researchers said that “much is not known about the high migration of insects, but it seems that many insects live at altitudes where swordfish fly.” Even waterfowl that hunt after sunset know that the hunting season lasts longer when the moon is clear.

An unexpected ‘natural experiment’ also took place in this study. Data on how the swordfish reacted during a total lunar eclipse in the wintering area remain. When the full moon rose, the five swordfish climbed to an altitude of 3,000 to 4,000 meters, but the moon disappeared during a lunar eclipse from 4:30 a.m. to 1 p.m. The birds immediately lowered their height to 400 meters. “Nature’s experiments have shown that moonlight can have a profound effect on swordfish night flying,” the researchers said. Professor Haydenstrom said, “The behavior of the swordfish revealed this time is interesting because it is reminiscent of the suplancton in the ocean moving vertically up and down under the moonlight.” Quoted papers: Current BiologyDOI: 10.1016 / j.cub.2022.03.006 Correspondent Joe Hong-siop ecothink@hani.co.kr

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