Brian Sweeney

Imagine being only a few months old, leaving Alaska, and flying across almost the entire Pacific Ocean without ever having made the journey before. The bar-tailed godwit known as B6 departed Alaska and touched down in northeastern Tasmania 11 days and one hour later. Its satellite tag recorded a journey of roughly 13,560 km (8,425 miles) without landing, making it the longest documented nonstop migration by a bird. Even more remarkable is how these birds prepare. Before migration, bar-tailed godwits build enormous fat reserves, sometimes nearly doubling their mass. At the same time, organs that aren’t as useful during flight, including parts of the digestive system, can shrink while the flight muscles and heart become larger. Once B6 was over the Pacific, there was effectively nowhere to stop. Godwits are shorebirds, not seabirds adapted to resting and feeding on the open ocean. Researchers tracked B6 remaining airborne through both day and night until it reached Tasmania. And this wasn’t an experienced adult following a route it had flown many times. B6 was a juvenile on its first southward migration. Scientists had tagged it as a chick in Alaska only months earlier. The bird’s body was essentially transformed into a biological long-range aircraft: load up on fuel, reduce unnecessary weight, strengthen the machinery needed for flight, then burn through those reserves for more than a week. No airport. No refuelling. No navigation system built by humans. Just a young bird crossing an ocean on instincts written into its biology.