ABSTRACT
The defi nition of migration is much more than a semantic issue, as pointed out by Hugh Dingle in his book ‘Migration: the biology of life on the move’ (Dingle 1996). Dingle (1996) and Dingle and Drake (2007) advocated that the defi nition ought to focus on individuals and on its behavioral aspects, even though migration can be described regarding its population outcomes. Therefore, taking this framework into account, Dingle (1996) considered that the defi nition proposed by J. S. Kennedy, in 1985, is the one that best describes migration across taxa. Thus, migration is defi ned as a persistent, undistracted and straightened-out movement, achieved through the animal’s locomotory means or by actively seeking a transport medium (e.g., air or water currents), during which individuals remain undistracted by the resources they might fi nd during migration by temporarily inhibiting ‘station-keeping responses’, and that might be repeated later in life (see J. S. Kennedy’s defi nition in Dingle 1996, p. 25). For Dingle (1996), Kennedy’s defi nition is the best defi nition of migration because (a) it emphasizes the organism’s behavior and (b) it is predictive and not only descriptive, in the sense that it enumerates behavioral traits that a truly migratory animal should fulfi ll to be considered as such.
