The Seabird’s Cry: The Lives and Loves of Puffins, Gannets and Other Ocean Voyagers

by Adam Nicolson

The Scottish ornithologists Bob Furness and David Bryant have investigated the energy budget of fulmars in different wind conditions. If it were calm and the bird had to flap its wings to move all day – they never do, because a calm day is when you will find fulmars sitting on their nests or the sea – they would have to expend 2,000 calories, thirteen times what they would consume sitting or sleeping doing nothing. As the wind increases, life becomes more viable so that when it is blowing at about 20 miles an hour, or Force 4–5, when the sea is just beginning to be covered in breaking crests, they can glide most of the time and the energy they expend on the wing is, astonishingly, as low as what it would be if they were sitting on the nest. At that speed, they still have to beat their wings about once every second, but when the wind notches up a little further, to about 25 miles an hour, or Force 5 to 6, flying costs them nothing. It is the magic horizon. In those winds, fulmars almost never beat their wings at all, but drink in the energy they need from the wind around them.