A cygnet has died and three other chicks were left fighting for survival after gallons of oil was tipped into a Dudley canal.

The parent swans were also discovered caked in oil in the Dudley No 2 canal where it runs through Bumble Hole nature reserve in Netherton.

Glynn Halford from the Friends of Bumble Hole said he was almost certain the oil had been poured into the canal deliberately – and branded the culprits “idiots”.

Mr Halford said the volunteers had been desperately saddened by the incident as the family of swans had been regular visitors.

He added: “We are very upset that some idiot has dumped a load of engine oil in the canal killing a cygnet and harming the other chicks.

“With the sheer volume of oil there was in the canal it is unlikely it was a leak or accidental spillage.

“I would like whoever dumped the oil to see how the swans looked and realise what they have done.”

One of the volunteers was walking along the towpath when they spotted the male swan sitting under a tree covered in oil.

The mother, who had gone in search of her partner, was discovered with her chicks about a mile up the canal.

Swan Rescue, based at Bishops Wood in Ombersley, was called and the swans were taken there for treatment on Sunday but the following morning one of the cygnets died.

Centre owner Nick Lee said the others were making a good recovery.

He said: “We wish people would be more responsible when getting rid of oil.”