In a couple of weeks the bar tailed Godwits will leave Alaska to make a journey lasting about 9 days, across the Pacific to New Zealand. Some will be adult birds who have made the trip before; they will return to precisely the same beaches they left from some time in March. Some will be juveniles who will, for the first time, find their way here across 12,000 km of empty ocean. This is astonishing enough, but a recent study by the University of Groningen, which involved implanting tiny transmitters into the abdominal cavities of some birds found something almost beyond comprehension. Last year the overwhelming majority of birds set off, from their various departure points, so that their flight paths would take advantage of a weather system 1500km to the south, and which the birds would not encounter for several days. How does something with a brain the size of a thimble do that? The cop out answer, "by instinct" just won't do. (So what, exactly is instinct, and how, ...