Staff and volunteers have rescued 12 sheep and lambs following a spate of vandalism to livestock fencing at the nature reserve.
The rescued animals had become tangled in sections of damaged barb wire, whilst others had been able to escape from their grazing areas.
The Nottinghamshire Wildlife Trust said there has been damage to 150 separate sections of fencing in the last few days and estimates that the repair bill will run into thousands of pounds.
Head of Communications Erin McDaid said: “Whoever is doing this has clearly got no regard for animal welfare or the financial cost to us as a charity.”
“The level of extra work and stress being caused to our dedicated staff and volunteers is also unacceptable,” he said.
Image: Sheep from the Nature Reserve caught in the damaged wire fencing
Adult sheep and new born lambs have been affected and the charity says the level of damage has come at the worst possible time of year – in the middle of lambing season.
In one incident a ewe and a day old lamb were trapped in the wire.
Animals may now need to be moved to other sites and some areas of important habitat may not get the level of grazing they need.
McDaid added: “It’s sickening that people can commit such pointless and reckless crimes without a thought for others or the animals involved.”
Retford Police are investigating the incident and are urging anyone with information to contact them on 01909 500999.
