Threat to Suffolk bird life

SUFFOLK'S birds are under threat as their riverside habitats are washed away – and ever larger ships are being held to blame.The River Orwell is home to a plethora of wading birds from redshanks to godwits to dunlins.

SUFFOLK'S birds are under threat as their riverside habitats are washed away – and ever larger ships are being held to blame.

The River Orwell is home to a plethora of wading birds from redshanks to godwits to dunlins. But the days of seeing birds feeding in the mud banks at the river's edge could be numbered.

Mick Wright, field officer for Suffolk Wildlife Trust, said: "Most wading birds are affected – redshanks, grey plovers, dunlins, turnstones, ring plovers, knots and curlews.

These are all birds that prefer soft, oozy mud banks and their numbers are all declining."

Birds that prefer sandier mud banks, such as oystercatchers, are not faring too badly as these mud banks – often in the Orwell's upper reaches – are accreting.

But the birds preferring softer mud banks and salt marshes are in difficulty as their habitats – found in the lower reaches of the Orwell and on the coast – are eroded away.

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Mr Wright added: "The mud banks and the salt marshes have been eroding more than usual in the past 20 to 30 years.

"Some of this is due to natural wave erosion, but some of it is due to the heavier traffic on the river.

"The river's water velocity has become faster after the river was dredged to allow larger ships to pass – most notably in 1998 in the creation of the Harwich harbour approach.

"Ship wash, from the bigger ships used nowadays, is also a significant factor. As the ship goes through the water, the bow wave splashes onto the shore. If it is low tide, this scours the mud banks and if it is at high tide, the wave breaks into and erodes the shore-line.

"There is also less sewerage in the river now, which means there are less nutrients for the ecosystem, but we don't know how this is affecting the bird life yet."

Traffic on the River Orwell is increasing, hitting 3.3 million tonnes last year. This is, however, still below the record 1989 level of 5.5m tonnes.

Both Harwich Haven Authority and Associated British Ports at Ipswich and Felixstowe are aware of the problem – but deny that ship wash from larger and more frequently passing ships is the foremost cause.

John Brien, assistant engineer of Harwich Haven Authority, said: "It is difficult to disagree that ship wash is affecting birds, but traffic is only now reaching the levels it was at ten to 15 years ago."

He added that decreased sewerage in the river and higher water levels generally also had a part to play.

Both Harwich Haven Authority and Associated British Ports actively monitor the bird life of the river. As a condition of the river dredging, Harwich Haven Authority also has to dump natural silt back into the water at low tide, which is then carried along at high tide to replenish the mud banks.

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