Fast and fuel ef cient ? Optimal use of wind by ying albatrosses

The in£uence of wind patterns on behaviour and e¡ort of free-ranging male wandering albatrosses (Diomedea exulans) was studied with miniaturized external heart-rate recorders in conjunction with satellite transmitters and activity recorders. Heart rate was used as an instantaneous index of energy expenditure. When cruising with favourable tail or side winds, wandering albatrosses can achieve high £ight speeds while expending little more energy than birds resting on land. In contrast, heart rate increases concomitantly with increasing head winds, and £ight speeds decrease. Our results show that e¡ort is greatest when albatrosses take o¡ from or land on the water. On a larger scale, we show that in order for birds to have the highest probability of experiencing favourable winds, wandering albatrosses use predictable weather systems to engage in a stereotypical £ight pattern of large looping tracks. When heading north, albatrosses £y in anticlockwise loops, and to the south, movements are in a clockwise direction. Thus, the capacity to integrate instantaneous eco-physiological measures with records of largescale £ight and wind patterns allows us to understand better the complex interplay between the evolution of morphological, physiological and behavioural adaptations of albatrosses in the windiest place on earth.