Two four-week-old moorhen chicks have been shot dead with airguns at a nature reserve in County Durham.
The Wingate Quarry reserve has also seen a spate of vandalism in recent weeks and locals are being urged to keep an eye out for the culprits.
Wildlife officers have found evidence of drinking parties by groups of youths at the county's nature reserves, with property damaged and wildlife affected.
Local residents are now being asked to report anti-social behaviour to police.
'Mindless louts'
Ian Armstrong, wildlife and ecology officer for Durham County Council, said that people living near the Wingate Quarry reserve had been sickened by the latest incident.
He said: "The shooting of these chicks has taken the problem to a new and worrying level.
"These reserves exist to help protect wildlife, and give them a place where they can live and breed safely.
"Sadly, the behaviour of a few mindless louts is spoiling the enjoyment for many, many more people.
"I would ask people to help us protect our local nature reserves and the rare and valuable wildlife they contain by being vigilant and reporting anything suspicious to the police."