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  • In May of 1822, Count Christian Ludwig von Bothmer

  • shot down a stork over his castle grounds in North Germany.

  • However, he wasn't the first person to hunt that specific bird.

  • Upon recovering the stork,

  • von Bothmer found it impaled by a yard long wooden spear.

  • A local professor determined the weapon was African in origin,

  • suggesting that somehow, this stork was speared in Africa

  • and then flew over 2,500 kilometers to the count's castle.

  • This astonishing flight wasn't just evidence of the stork's resilience.

  • It was an essential clue in a mystery that plagued scientists for centuries:

  • the seasonal disappearance of birds.

  • Ancient naturalists had various theories to explain the annual vanishing act

  • we now know as migration.

  • Aristotle himself proposed three particularly popular ideas.

  • One theory was that birds transformed into different bodies that suited the season.

  • For example, summer time garden warblers

  • were believed to transform into black caps every winter.

  • In reality these are two distinct speciessimilar in shape and size,

  • but never appearing at the same time.

  • Over the following centuries, birds were said to morph into humans,

  • plants, and even the timbers of ships.

  • This last transmutation was especially popular with many Christian clergy.

  • If barnacle geese were truly made of wood,

  • they could be deemed vegetarian and enjoyed during meatless fasts.

  • Aristotle's second and even more enduring hypothesis was that birds hibernate.

  • This isn't so far-fetched.

  • Some species do enter short,

  • deep sleeps which lower their heart rates and metabolisms.

  • And there's at least one truly hibernating bird:

  • the common poorwill sleeps out winters in the deserts of North America.

  • But researchers were proposing much more outlandish forms of hibernation

  • well into the 19th century.

  • Barn swallows were said to remove their feathers and hibernate in holes,

  • or sleep through the winter at the bottom of lakes and rivers.

  • Aristotle's final theory was much more reasonable,

  • and resembled something like realistic migration.

  • However, this idea was also taken to extremes.

  • In 1666, the leading migration advocate was convinced that each winter,

  • birds flew to the moon.

  • It might seem strange that prominent researchers considered such bizarre ideas.

  • But to be fair, the true story of migration

  • may be even harder to believe than their wildest theories.

  • Roughly 20% of all bird species migrate each year,

  • following warm weather and fresh food around the planet.

  • For birds who spend their summers in the northern hemisphere,

  • this journey can span from 700 to over 17,000 kilometers,

  • with some flights lasting as long as four months.

  • Birds who migrate across oceans may soar without stopping for over 100 hours.

  • Sleeping and eating on the fly, they navigate the endless ocean

  • by the stars, wind currents, and Earth's magnetic field.

  • Tracking the specifics of these epic expeditions is notoriously difficult.

  • And while birds often take the most direct route possible,

  • storms and human development can alter their paths,

  • further complicating our attempts to chart migration.

  • Fortunately, Count von Bothmer's stork offered physical proof

  • not only that European storks were migrating south for the winter,

  • but also where they were migrating to.

  • Ornithologists across the continent

  • were eager to map the trajectory of this flight,

  • including Johannes Thienemann.

  • Owner of the world's first permanent bird observatory,

  • Thienemann was a major public advocate for the study of birds.

  • And to solve the field's biggest mystery,

  • he wrangled an army of volunteers from across Germany.

  • His team used aluminum rings to tag the legs of two thousand storks

  • with unique numbers and the address of his offices.

  • Then he advertised the initiative as widely as possible.

  • His hope was that word of the experiment would find its way to Africa,

  • so people finding the tags would know to mail them back with more information.

  • Sure enough, from 1908 to 1913,

  • Thienemann received 178 rings, 48 of which had been found in Africa.

  • Using this data, he plotted the first migration route ever discovered,

  • and definitively established that storks were not, in fact, flying to the moon.

In May of 1822, Count Christian Ludwig von Bothmer

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    林宜悉 posted on 2020/12/17
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