River Arun Estuary Wildlife

The birds and habitats of the lower Arun valley

The lower River Arun and its estuary support a rich and varied wildlife community, with the tidal mudflats, reed beds, water meadows and riverside habitats providing food and shelter for a wide range of birds, mammals, fish and invertebrates. The estuary is one of the ecological treasures of the Littlehampton area, and the wildlife it supports is visible to anyone who walks the riverside paths with patience and an observant eye.

Wading birds are the most conspicuous wildlife of the estuary, feeding on the mudflats that are exposed at low tide. Curlews, with their distinctive long curved bills and mournful calls, are a characteristic bird of the Arun mudflats, probing the mud for worms, crustaceans and other invertebrates. Redshanks, oystercatchers, dunlins and ringed plovers also feed on the mud, each species exploiting a slightly different food source or feeding technique, allowing multiple species to share the same habitat without direct competition.

Herons and egrets are regular sights along the river, standing motionless in the shallows waiting for fish, frogs and other prey to come within striking distance. Grey herons, with their long necks and deliberate wingbeats, are a familiar presence, while the smaller and more elegant little egrets have colonised the area in recent decades, having expanded their range northward from continental Europe. The egrets' pure white plumage is striking against the dark mud and green vegetation, and their presence adds a touch of the exotic to a very English riverscape.

The reed beds along the banks of the lower Arun provide habitat for specialist birds that depend on this increasingly rare habitat. Reed warblers arrive from Africa in April, building their nests among the reed stems and filling the air with their rapid, chattering song throughout the summer. Sedge warblers, reed buntings and Cetti's warblers also inhabit the reeds, though they are more often heard than seen, their songs rising from the dense vegetation as they defend territories and attract mates.

Mammals along the river include water voles, which have survived in the Arun valley despite catastrophic declines elsewhere in England. Water voles are shy, secretive creatures, most easily spotted by their characteristic plop as they dive into the water when disturbed. Their burrows in the riverbanks are identifiable by the neat, round entrance holes at the water's edge, and their feeding signs, including neatly nibbled vegetation left on the bank, confirm their presence. Otters have also been recorded on the Arun, a sign of improving water quality and the availability of the fish that form their diet.

The estuary habitat is maintained by the tidal cycle, which twice daily floods and drains the mudflats, delivering nutrients and removing waste. The health of the estuary depends on the quality of the water flowing down the Arun from the Sussex Weald, and on the management of the land around the estuary margins. Conservation efforts by the Sussex Wildlife Trust, the RSPB and local wildlife groups contribute to the protection of this valuable habitat and the species that depend on it.