Two cygnets have been torn apart in a suspected dog attack before efforts were made to torch their remains.
The young birds were among four born to a pair of swans which have nested at the pond next to Downhill Sports Complex, with the grim discovery of their bodies made on Tuesday evening.
After another of the youngsters went missing, just one bird is left, with residents from their area scared for its safety after a series of incidents where youths have been seen to target the wildlife and threaten dog walkers and their pets.
A mother and daughter who use the pond as a place to exercise their dogs have reported the incident to Northumbria Police, while councillors representing the community have joined them in condemning the slaughter of the cygnets.
The spot is just a short distance away from allotments where one horse had to be put to sleep after it was slashed and another died in a suspected arson fire in the same attack last month.
The 26-year-old daughter, who along with her mum has asked not to be identified for fear of reprisals, said they believed a dog had been used to inflict injuries on the swans before a fire was started on the waterside.
“We think a dog has been set on them because of what’s happened to them,” she said.
Whoever did this is just horrible, how can people do this to an animal?Concerned resident
“They’ve definitely been killed by something.
“When I heard I was really upset and contacted the police.
“It’s just disgusting, I don’t know who would want to do something like that to a living thing.”
Her 50-year-old mum said: “I was just really, really upset because I have watched the cygnets since they hatched and have been reared and they were almost as big as their parents.
“When I saw what had happened, I was shaking and felt sick, I had to fight the tears until I got home and rang my partner and then my daughter.
“Whoever did this is just horrible, how can people do this to an animal?”
In August, Sunderland City Council cleared up the pond to create a better habitat for the swans after wheelie bins, mattresses and other waste had been dumped in the water.
Redhill ward member and cabinet secretary, Councillor Paul Stewart, said: “Like many in the community we are so saddened to hear the news of what has happened to our swans in the Downhill Sports Complex Pond.
“We had recently been working with the community to clear up the debris left by fly-tipping, improving the pond for the swans and its other inhabitants.
“We are angered by what has happened and would urge any member of the public who may have seen anything to contact local councillors or the police as the swans have a right to live here peacefully.
“If there has been a dog or dogs involved in this, and if you don’t know how your dog is going to behave then you should take responsibility and keep dogs on a lead.”
A Northumbria Police spokesman said: “On Tuesday, police received a report that swans had been killed near the Downhill Sports Complex, Sunderland.
“Inquiries are ongoing into the matter.”
He added anybody who has any information regarding the incident is asked to contact police on 101 or by emailing email@example.com.