大象传媒

Of all the amazing stories of bird migration none is more epic than that of the Arctic Tern, sometimes nicknamed the sea swallow because of its graceful, streamlined shape and long tail streamers.

Lovers of the light, Terns spend their lives in its constant pursuit. They arrive in Scotland in May and spend their summer breeding and raising their young before setting off on the mind-bogglingly long 20,000 mile migration to Antarctica. With a lifespan of 30 years, it's the equivalent of flying to the moon and back. And it means arctic terns see more daylight than any other creature on the planet.

It's in telling this story that Karine is led to one of the tern's strongholds, the magical Isle of May, five miles off the Fife coast. For humans, the Isle of May has its own light-related significance. Since 1635, sailors have been kept safe by a lighthouse there, the first was a crude affair, but it became the site for the first of the Stevenson lighthouses, and that majestic building still stands.

Now the island is best known for its seabird colonies and the scientific research into them. Speaking to scientists there, Karine will further explore the mysteries of bird migration, a recurring theme in many of her works. So much of it revolves around light and dark. While the terns may be seeking the summer sun it's by the stars that they find their way. Polaris, the pole star is crucial; and this leads Karine to speak with Stephen Emlen, the professor of neurobiology and behaviour that discovered this by taking live buntings into a planetarium and systematically blocking out constellations to see how they reacted. The experiment showed that the birds are primed for night time navigation, not by an inborn star map but by paying "close attention to the movement of the sky. They're hardwired to pay attention to something, which then takes on meaning."

Produced by Peter McManus
Written and presented by Karine Polwart
Music by Karine Polwart and Pippa Murphy

Vocals - Karine Polwart
Piano - Dave Milligan