This large, distinctive bird can be found on its own or in groups of up to thousands in fresh, brackish or salt water lakes, swamps and rivers containing underwater and emergent vegetation. Black swans prefer permanent wetlands but will move about as opportunities arise. When wet areas dry up during the breeding season adults will abandon nests, eggs and even cygnets and moves to another wetland. The Swan River was named after these birds, when first seen by Europeans in 1697. They were hunted to extinction in New Zealand but have since been reintroduced there. Black swans are almost exclusively herbivorous, generally feeding on aquatic and marshland plants though also able to forage for pasture plants onshore. They are found in large numbers around areas of macrophyte beds feeding in shallow waters. Swans use their long neck to graze on macrophytes growing from the mud and sediment, and can also dab at the waters surface and filter food through their beak. Black swans build a huge nest – up to 1.5 m across and 1 m high – in shallow water or on islands. During breeding they are prone to disturbance from boaters and jet skiers, which can jeopardise the survival of their eggs or chicks.