LéVY flights are a special class of random walks whose step lengths are not constant but rather are chosen from a probability distribution with a power-law tail. Realizations of Lévy flights in physical phenomena are very diverse, examples including fluid dynamics, dynamical systems, and micelles1,2. This diversity raises the possibility that Lévy flights may be found in biological systems. A decade ago, it was proposed that Lévy flights may be observed in the behaviour of foraging ants3. Recently, it was argued that Drosophila might perform Lévy flights4, but the hypothesis that foraging animals in natural environments perform Lévy flights has not been tested. Here we study the foraging behaviour of the wandering albatross Diomedea exulans, and find a power-law distribution of flight-time intervals. We interpret our finding of temporal scale invariance in terms of a scale-invariant spatial distribution of food on the ocean surface. Finally, we examine the significance of our finding in relation to the basis of scale-invariant phenomena observed in biological systems.