Migration baked into genes since antiquity

The topic of animal/bird/insect migration is a hot scientific one and there are plenty of ways for an amateur like me to approach it. After a few promising but unproductive false starts, a friend pointed me to “Incredible Journeys: Exploring the Wonders of Animal Navigation“, which hit our shelves in April. Author David Barrie is my kind of elucidator: an ex-diplomat and campaigner, he’s a sailing nut cum adventurer and his book “Sextant” tackles human navigation. He writes eloquently and with a surety of control that is intoxicating. Every chapter took me further along towards glimpsing how Cranes, among the half of Earth’s bird species who migrate, might do so.

One thing I needed to understand: bird navigation is not just “wow!”, it’s a lifelong existence-gambling purgatory (call it an adventure if you like, what word we choose depends on our conception). Yes, migration is remarkable, but it’s also a body-depleting, fraught plunge into the unknown each and every time. How a given bird species migrates – from breeding grounds to overwintering grounds – and indeed how an individual bird executes – is something wrought by evolution over untold years.

Each year’s to and fro trips can be fucked up by weather, wind, predators, luck, and of course humankind’s inexorable grabbing of pathways, feeding stops, and destinations.

And the variety of migration tales! For every magazine-friendly whooper “hero” story of a tiny bird that bravely plugs away across land and sea, losing a huge chunk of body weight, to “miraculous” arrivals at the same stop as last year, Barrie relates narratives that contrast and complexify and mystify.

For example, we’re used to birds breeding in an optimum location and then flying south or north to escape the cold. But the murrelet breeds on remote islands across the Pacific, 8,000 kms, and migrates west to the waters of China and Japan.

No other bird is known to undertake a similar east-west migration in the Pacific and why the murrelet does so is a mystery, as indeed is its method of navigation. The researchers think this extraordinary journey may reflect the route the birds took–in the long distant past–as they expanded their range from an original base in East Asia to North America.

Call me easily impressed but here is a once-off migratory path, not taken by any other birds, baked into the murrelet’s genes since antiquity!