Salt marshes and tidal flats attract shorebirds for feeding, roosting and nesting. Different degrees of vegetation cover, fluctuating water depths, and varied sediment composition provide habitats that meet the needs of a wide variety of shorebird and other waterbird species, which have different requirements for foraging, roosting and nesting. Tidal creeks (networks of small drainage channels in tidal areas) provide foraging habitat for fish and invertebrates (Olmstead & Fell, 1974; West & Zedler, 2000). During high tide, these animals are able to invade the salt marsh via tidal creeks in order to feed and are subsequently preyed upon by larger fish and birds (Olmstead & Fell, 1974). Tidal flats have therefore been described as ‘the supermarkets of the sea ’ because of their abundance of food that shorebirds can feed on, such as polychaete worms, molluscs and crustaceans. Many migratory shorebirds use intertidal areas as stepping stones to re-fuel before embarking on, or during, their long migrations and during the non-breeding period. Resident species of shorebirds and other waterbirds depend on these food sources throughout the year.
Tidal flats and salt marshes occur in estuarine systems worldwide, providing both ecological and economic value. However, these systems are vulnerable to a range of threats, which overall have led to a significant reduction in their extent. Top: Salt marshes at Saeftinge, Speelmansgat, The Netherlands [Credit: Edwin Paree]. Left: Shorebirds feeding on a tidal flat on the west coast of South
Korea [Credit: Peter Prokosch, www.grida.no/resources/4394].
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