Police are investigating after a man was filmed dragging a swan by its neck near Caerphilly Castle.
A witness says a man carrying a bottle of alcohol grabbed the bird and pulled it along a path before onlookers shouted at him to stop.
Brandon Ryzy, 21, filmed the attack on Sunday close to the town’s Winter Wonderland attraction.
He said: “I was walking home from Christmas shopping and he had gripped a swan/goose by the neck and dragged it across the path saying it attacked his child, but had no child with him.”
Mr Ryzy said the man seemed to be under the influence of alcohol.
He shouted at the man and ordered him to release the bird which “seemed to be in shock” following the incident.
“I’m just glad I was there to stop him,” he said.
“I watched the man walk off and stayed with the bird to see if it could get itself back to the moat. It seemed quite fragile and was moving slowly.”
Gwent Police confirmed the force was investigating and appealed for information,
A spokesman said: “We did receive this report of concern, where a man had grabbed a swan by the neck, the caller advised he then let it go and it ran back into the water.
“The call came in at about 4.20pm on Sunday, Dec 3. Officers attended and searched the area, the man was not found and enquiries are ongoing to trace him.
“Anyone with any information can call police.”
An RSPCA spokesman added: “This is a very distressing video and anyone who has any first-hand information about this incident can contact the RSPCA in confidence on 0300 1234 999 or Gwent Police on 101.”