THE colony of swans at a North-East beauty spot is starting to recover after a mysterious lead poisoning outbreak led to the death of up to 100 of the birds.

But a local vet, who carried out tests on many of the affected mute swans at Chester-le-Street’s Riverside Park, remains convinced the outbreak was a deliberate act.

Wildlife experts, the Environment Agency, the RSPCA and police were involved in the investigation into the decimation of the flock on the stretch of the River Wear running through the popular park, between Chester-le-Street and the grounds of Lumley Castle.

There was an outcry when the death toll among the swans rose rapidly in February and March.

Post-mortem examinations showed they had extremely high levels of lead poisoning, but tests on samples from the river showed there were no significant changes in pollution levels in the water.

Accidental poisoning from shot or dumped batteries would have shown up in the birds’ gizzards as chunks of the metal.

But the theory which emerged was that the swans were fed balls of bread which were laced with powdered lead.

The circumstances led vet Gill Maxwell, from Cestria Veterinary Centre, to become convinced the culprit was a deliberate poisoner seeking to in some, way cull the colony.

“Fortunately, because of all the publicity, it seemed to scare off the individual concerned.

“We’re totally convinced that this was deliberate poisoning, and had a suspect in mind, but couldn’t prove it.

“The lead levels found in the birds and the speed of onset of clinical signs were just totally wrong for an environmental contamination.

“If it had been something catastrophic, there would have been absolutely nothing left alive in the Wear.”

No more swans have died in suspicious circumstances over the last six months and numbers are said to be slowly recovering.

The park is a popular area for families to go close to the birds and to feed such usually high numbers.

But Ms Maxwell said: “Unfortunately, as the levels in affected birds were so very high, most of those referred to a hospital practice for treatment did not actually recover.

“They seemed to improve initially, but then crashed later on.

“Very few recovered to go on to be released."

She believed between 80 and 100, of the approximate 130-plus strong flock died, impacting the local population for some time as many of the victims were young adults who were yet to breed.