You begin as a white egg in a dark crevice. Your parents glued this nest to a wall with their own saliva. You are one of two eggs in a cup of straw and feathers.
Your beak taps against the shell for hours. You have no feathers at all. Your eyes are sealed completely shut. You weigh less than a coin.
Your parents return with food balls stuck in their throats. Each ball contains hundreds of insects bound with saliva. You open your pink mouth wide.
Rain keeps your parents away for two whole days. Your body drops into a deep sleep called torpor. Your temperature falls and your heart slows. You wait in the dark.
At three weeks old you begin doing press-ups. You push down on your wings to lift your body. Your muscles must grow strong.
The day comes to leave the nest forever. You crawl to the edge of the nest cup. You fall into open air below. Your wings catch the wind.
You fly for the first time. The ground below looks strange and dangerous. You will not touch it again for years.
Night falls over the city below. You remain in the sky above. You glide upward on warm air. Other swifts surround you in the dark.
You learn to catch flies with your wide mouth. You scoop water from ponds without landing. The air is your only home.
Summer ends in the European sky. Something pulls you south toward Africa. You join thousands of swifts on the move. The journey spans thousands of kilometers.
You cross the Mediterranean Sea without stopping. The blue water stretches below for hours. You beat your scythe-shaped wings without rest.
Some swifts follow the Atlantic coast to avoid the Sahara. Others cross the desert itself. You fly onward through the heat.
A storm hits your flight path hard. The insects vanish from the sky. You feel hunger deep in your hollow bones. You must keep flying or die.
You rise higher at dusk to nearly two and a half kilometers. The air grows cold and thin. You glide downward through the night.
Your brain must rest while you remain airborne. You likely sleep in brief snatches while gliding. Scientists still wonder exactly how.
A flat crab-like insect clings to your feathers. It is a louse fly. It drinks your blood during flight. It will stay with you for life.
You spend ten months without touching any surface. You eat in the air above Africa. You drink without ever landing. You sleep while gliding downward.
The African rains bring clouds of insects. You feast above the humid savanna. Your body stores fat for the return.
You have flown hundreds of thousands of miles already. Over your whole life you may reach two million. That equals four trips to the moon and back.
Spring pulls you north again. You follow the Great Rift Valley upward. The air grows cooler every hour. Europe waits beyond the horizon.
You arrive in a European city in late April. The streets look familiar after a year away. You search for your old nest hole.
You find your mate from last year. She enters the nest crevice first. You stroke her chin with your bill. This bond will last for life.
You both gather feathers and straw on the wing. You glue them to the wall with sticky saliva. The nest grows slowly day by day.
You lay two white eggs in the half-built cup. Your body is warm against them for nineteen days. Your mate takes turns sitting too.
The first chick breaks free. It is naked and completely blind. You were once the same. You must now feed it every few hours.
Bad weather returns to the city. The insects disappear from the sky. Your chicks slow their hearts. They enter torpor to survive.
The chicks do press-ups at three weeks old. They push against the nest floor. Their wings grow stronger every day. Soon they will fall into the sky.
They leave the nest at last. They do not return again. They will stay airborne for two full years. You watch them vanish into the screaming flock.
Evening comes to the warm city. Twenty swifts gather above the rooftops. They scream in high and low voices. The sound means summer has arrived.
You dive through the air at one hundred and eleven kilometers per hour. Your wings fold back like a crescent moon. Nothing on earth can catch you.
You cover eight hundred kilometers in a single day. Your wings beat deep and fast. Then you glide for miles without a single stroke.
You are seventeen years old and still returning. Your mate greets you at the same hole. The nest has lasted longer than most human marriages.
Your legs are short and weak. You cannot walk on flat ground. You cannot hop on flat ground either. You are built only for vertical walls and endless air.
You skim the surface of a lake to drink. Your lower beak slices the water at full speed. You swallow without breaking stride.
You mate with your partner while both flying. Your bodies lock for a few seconds. Then you separate in midair. You continue hunting for insects.
Your ancestors nested in trees and cliffs. Now you live in human buildings. Their eaves and tiles are your cliffs.
Your scream cuts through the warm evening air. People below look up at you. They smile at the dark shapes. They know summer has truly begun.
Old buildings are torn down around you. Gaps are sealed with fresh mortar. Eaves are closed with new plastic. Your nest hole vanishes into smooth concrete.
Some humans now build special bricks with holes inside. Scotland made these bricks mandatory by law. A few cracks in the wall can save us.
You are a creature of pure motion. The ground was never your home. Your life is the space between earth and sky.