The birds arrive one day by the thousands, hang around for a while and then are gone, seemingly overnight. Each year like clockwork, butterflies descend like a cloud into the trees of California. Examples of migratory behavior are everywhere and though we have come to understand what is happening, the why and how have proved more elusive.
As recently as the 19th century these mass appearances were a mystery. Birds for example were thought to burrow under the mud in winter; some suggested that they might even change from one species to another to survive the cold. One rather famous fellow hypothesized that birds flew to the moon!
It wasn’t until a hunter in England shot and killed a stork, a stork with an african arrow piercing its neck, that migratory patterns began to be understood. The mysteries of nature are thus revealed, although to be clear I was hoping for the Moon Stork.
And we have found that it is not just birds but insects, bats, sea turtles, salmon and a whole host of other beings that make these perilous journeys, placing their trust in instinctive certainty. These species live out their life cycles in multiple places, going to or away from some environmental imperative to optimize survival and longevity.
How do they accomplish this without access to the internet, GPS and geosynchronous satellites? Apparently migration uses a number of different mechanisms and some species use them in combination, hedging their bets. Earth’s magnetic field is a favorite – some animals have tiny particles of magnetite embedded in their bodies and cells. Dolphins seem to read the contours of the ocean floor while migratory birds depend on the sun, its angle in the sky and the time of year.
Might we, through our deeds and desires, disrupt the very signals upon which survival depends? Living in harmony with others is not our strength, but I am forever hopeful.
And so they come and go, come and go, riding the physics of the earth.
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