This talk is about how birds co-operate and the mechanisms they employ to save energy during flight. The distinctive V formation of bird flocks has long intrigued researchers and continues to attract both scientific and popular attention. Through the use of novel biologging technology, and by working with the reintroduction scheme of the critically endangered Northern Bald Ibis, studies have been performed on the relative positioning of individuals in a V-formation, and the co-operative aerodynamic interactions that take place, at a level and complexity not previously feasible.