A Muscovy duck is thought to have been killed using antifreeze, while other birds have been found with pink staining on their feathers
A duck poisoner is thought to be on the rampage in the Devon town which inspired the Sherlock Holmes epic The Hound of the Baskervilles.
Residents of Buckfastleigh, on the edge of Dartmoor, fear a killer is in their midst after one of the quiet market town's Muscovy ducks died after ingesting a toxic pink substance believed to be antifreeze.
Other have been found with their feathers covered in the colourful chemical.
Pam Barrett who cares for the feral flock on the town's Orchard Millennium Green is convinced they are victims of foul play - possibly at the hands of a local who objects to the protected birds’ droppings.
Mrs Barrett told the Daily Telegraph: "I discovered the ducks were covered in a bright pink staining - a fluorescent pink - a very odd colour.
"I researched what poisons were pink and the colour and death all points to antifreeze.
"If that's the case it's despicable.
"It's cruelty and would be destruction of a much loved group of animals which have overwhelming support in the town.
"To do such a thing in a public place because of a vendetta against the ducks and risking the health of children and wild animals is absolutely horrific."
The duck which had ingested the poison died shortly after being taken to Dart Vale Vets.
Vet Vicky Roberts told the newspaper: "It was struggling to breathe and had a reddy, orange splashing on its feathers.
"If they are being poisoned with antifreeze it's a horrible way for a duck to die.
"If it is poison it would appear to be deliberate and that's a concern."
A spokesman for Devon and Cornwall Police said: "We are investigating this as a crime of causing unnecessary suffering to a protected animal.
"A duck is suspected of being poisoned with a pink liquid and later died."
Sir Arthur Conan Doyle is rumoured to have penned The Hound of the Baskervilles after learning of the story surrounding the death of Richard Cabel, Lord of the Manor of Brook, west of Buckfastleigh.