Within floodplain wetlands, flooding is recognised as the 'principal driving force responsible for the existence, productivity and interactions of the major biota' (Junk et al. 1989, p. 110). In addition, it has been proposed that biota in variable habitats develop strategies to adapt to variable flow (Walker et al. 1995). This chapter explores some of the strategies that waterbirds have developed, such as opportunism and flexibility, in response to variable flows. The adaptive capacity of waterbirds to flow variability, which is driven by Australia's variable climatic patterns, is particularly evident when comparing Australian waterbirds to those in the northern hemisphere. Australian waterbirds tend not to have clearly predictable patterns of movement, feeding ecology, reproduction, moult and habitat use (Kingsford and Norman 2002); rather, they exhibit many aspects of opportunism. In particular, many waterbirds have great dispersal capabilities, thereby providing the opportunity to search for ideal wetland habitats within the fluctuating mosaic of wetlands in arid and semiarid Australia (Roshier et al. 2001a, 200lb). In fact, the response of waterbirds to flooding and their innate ability to track floodwaters has long fascinated bird watchers in Australia (see, e.g., the account of the silver gull by Hobbs 1961).