Dispersal behaviour in fragmented landscapes: Routine or special movements?

Dispersal is a key process in ecology, evolutionary and conservation biology. Studies like mark-release-recapture work, show patterns of movement, but do not provide insight into the behavioural mechanisms. We review and comment recent results on animal dispersal behaviour. Dispersal through a landscape can be realised in two different ways: as a by-product of routine movements associated with resource exploitation (like foraging or mate-searching) with high levels of returning, or, as special, fast and directed movements designed for displacement. We illustrate and discuss both classes of movements as behaviourally different types. These types of movement imply different assumptions and consequences. We point at potential biases of current studies (like mark-release-recapture studies) towards routine, explorative movements. A more accurate knowledge of the dispersal behaviour is important to model dispersal with more biological realism, but also to better understand evolutionary consequences (e.g. uncoupled evolution of routine and special movements) and conservation (e.g. relative importance of corridors). The contribution of routine movements to dispersal is expected to decline with habitat fragmentation. A species’ mobility is not a static trait, but a multiple trait, the components of which may evolve rapidly. The possibility of uncoupled selection on routine movements and real dispersal movements remains to be evaluated. Yet, we are only at the beginning of understanding the behavioural ecology of dispersal movements. A more careful treatment of behavioural components of mobility within observational and experimental studies of animal dispersal is needed. & 2005 Gesellschaft für Ökologie. Published by Elsevier GmbH. All rights reserved.