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Australia's waterbirds are mostly nomadic, capitalising on highly variable aquatic resources in the arid interior (70% of the continent) for feeding and breeding. Waterbirds, unlike most aquatic organisms, can move between catchments, exploiting habitat wherever it occurs. In Australia, patterns of resource availability for waterbirds are mostly pulsed with peaks of productivity, coinciding with flooding and differing in time and space, affecting individuals, species and functional groups of waterbirds. Australian waterbirds are no different from waterbirds elsewhere, with their behaviour reflecting broad-scale resource availability. They respond to changing patterns of resource distribution, with rapid movements at spatial and temporal scales commensurate with the dynamics of the resource. The most serious conservation threat to waterbirds is a bottleneck in resource availability, leading to population declines, increasingly forced by anthropogenic impacts. River regulation and other threats (e.g. draining) reduce the availability of wetland habitat and decrease the probability of viable resource patches. It is axiomatic that waterbirds need water and such population bottlenecks may occur when the availability of water across the continent is limited. The rehabilitation of regulated rivers with environmental flows and protection of naturally flowing rivers in the arid region are essential for long-term sustainability of Australia's waterbird populations. [ABSTRACT FROM AUTHOR]

We can use aerial surveys of waterbirds to identify high-conservation-value wetlands, estimate species' abundance and track changes in wetland condition. Two major approaches prevail. Transects to estimate a few species (1–20, often ducks) are predominantly used in North America and counts of entire waterbird assemblages on discrete wetlands are favoured in Australia. Such differences reflect wetland type, discrete (whole count) and continuous (transect) sampling, different objectives and history. There are few continuous large-scale aerial surveys of waterbirds, despite cost efficiencies and effectiveness. We review the eastern Australian waterbird survey that samples about one-third of the continent (2.697million km2). Each October, during 1983–2007, all waterbirds were estimated on an average of 811 wetlands, within ten 30-km-wide survey bands, separately extending across latitudes from the east coast to central Australia. The survey has demonstrated the importance of arid wetlands for waterbirds and provided management data on distribution, abundance and breeding of waterbirds. Most significantly, long-term temporal data for individual wetlands provided strong evidence for the impacts of water resource development (dam building, diversion of water). These data have influenced wildlife management, river rehabilitation and restoration policies at a national scale. [ABSTRACT FROM AUTHOR]