Animal lovers have mounted patrols to stop youths using catapults to fire stones at a pair of nesting swans.

A security fence has also been erected to protect the birds.

Youths in East Worthing have been using catapults to fire stones at the swans, who are nesting in a small stream near Willowbrook Industrial Estate.

The duo are determined to protect their eggs, making them sitting targets for a barrage of rocks and rubbish which have been dumped nearby Concern mounted for the birds because the Easter school holidays give children more free time to attack.

In response, East Sussex Wildlife Rescue volunteers (ESWR), Plumpton College students and East Worthing residents have since been patrolling the nest at Willowbrook Road and Worthing Borough Council built the fence.

ESWR officer Trevor Weeks said the attacks amounted to three offences under the Countryside and Wildlife Act and criminal damage to Crown property, because all swans in England technically belong to the Queen.

Mr Weeks said the Queen's swan marker had been informed of the attacks and the birds could be moved if the abuse worsens.

He said: "I'm watching the swans closely to look for signs of distress.

"Mum is very wary of us and dad's a little bit more nervous than he should be. The fact the fencing is being put up is an additional stress for the swans.

"Being a narrow stream, people can get past the fencing and on to the opposite side of the bank. We will try to keep as high a profile as possible to keep them away."

Mr Weeks, who notified the council about the attacks, said it was an offence to interfere with swans, their nest and the eggs and the youths harassing them could be fined up to £5,000.

Chris Bradley, Worthing's parks manager, said: "There have been swans on that stream for quite a few years and we try to respond positively when someone comes to us in Mr Weeks' capacity.

"Obviously, there's still a possibility people could cause problems for the swans by getting over to the other side of the stream but people are now keeping an eye on the site and hopefully, they can keep the kids away while they are not at school."

A Worthing and District Animal Rescue Service officer said fly-tipping and abandoned cars made the area a "playground for hooligans".

The Environment Agency is launching an investigation in a bid track down the flytippers.