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As natural wetlands have disappeared around the world, artificial wetlands have increased. We found interesting differences in waterbird communities of two natural (Bundala Ramsar site) and seven artificial wetlands (irrigation tanks, salt ponds, rice paddies) in south-east Sri Lanka. Eight species exclusively used natural and one species artificial wetlands. Migratory species (shorebirds 64%, terns 47%) dominated species’ richness of natural lagoons, with densities of shorebirds 3–6 times greater than on artificial wetlands. Contrastingly, resident species (dabbling ducks, gallinules) contributed most to the diversity (59%) and density of waterbirds on artificial irrigation tanks. Cattle egrets dominated waterbird density (>70%) of rice paddies. Waterbird communities reflected physical and chemical character of wetlands: natural wetlands were shallow ( 1000 msm −1 ) compared to deep (>2 m) and freshwater (EC −1 ) artificial wetlands. Artificial inputs of water drained into the natural Embilikala lagoon changing its physico-chemical profile and disrupting the natural seasonal drying. Consequently its waterbird community was similar to artificial irrigation tanks, with shorebird species particularly impacted: densities half that of the other natural lagoon. Artificial salt ponds had similar physico-chemical properties to the natural Bundala lagoon and a similar waterbird community. Even though artificial wetlands supported waterbirds, they were not adequate replacements for loss of natural wetlands, favouring some species. Imposed hydrological stability degraded habitat quality for migratory shorebirds on one of our Ramsar site lagoons.

The biodiversity values of the wetlands in the Kakadu Region of northern Australia have been recognised as being of national and international significance, as demonstrated through their listing by the Ramsar Convention on Wetlands. Analyses of the wetland biodiversity have resulted in the production of species list for many taxa, and some population and community-level analyses of biomass and abundance, and the mapping of habitats at multiple scales. Wetland habitats include inter-tidal mud-flats, mangroves, hyper-saline flats, freshwater flood plains and streams. The tidal influence on the saline wetlands is pronounced, as is the influence of the annual wet-dry cycle of the monsoonal climate on the flood plains and streams. The vegetation is diverse and highly dynamic with rapid turnover of organic material and nutrients. The fauna is abundant with endemism being high in some habitats. Most fauna analyses have focussed on vertebrates with a large amount of information on waterbirds and fish in particular. However, despite extensive effort over the past two decades much is still unknown about the biota. While the invertebrate fauna in the streams has received some attention, a large taxonomic classification effort is required. The functional inter-relationships between habitats and species have largely not been assessed. Further, the ecology of many species is only cursorily known. At the same time there has been increased attention to pressures on the wetlands, such as weeds and feral animals, water pollution, and the potential impact of climate change and salinisation of freshwater habitats. Importantly, given the social context of the region, increased attention is being directed towards traditional use and management of the wetlands.