Resident birds have returned to Broughshane Waterfowl Park in County Antrim after an oil spill killed 13 of the flock.

The incident occurred after a home heating oil tank at a business premises in the Main Street area of Broughshane was vandalised. Police said about 200 litres (44 gallons) of oil leaked. The Northern Ireland Environment Agency (NIEA) was alerted on Thursday 22 October and has been involved in removing the oil waste. The agency identified the substance as home heating oil or kerosene.

More than 20 birds, including geese, ducks and swans, were taken to the USPCA headquarters for specialist care. The USPCA said all required bathing and treatment due to contamination, and some had ingested too much oil and died.

Gary Hayward, chairman of the Broughshane Environment Wildfowl and Wildlife Trust, said about 10 to 12 birds have returned, including two black swans and Nenes. He said they are back safely in their pens and are healthy. The birds returned on Monday morning.

The park, which had 120 birds, has reopened. In a social media post, The Waterfowl Pond said work is ongoing to address oil contamination and some pens remain out of bounds. Hayward said there is very little evidence of oil left as the NIEA has removed the majority, though some remains around the edges. Once the pens are clear, the remaining birds will be moved back.

Hayward said the NIEA had reduced the problems significantly and that the USPCA had been a great help in looking after the birds. The Waterfowl Pond thanked the USPCA and the public for their support.

Police said enquiries into the incident are ongoing and appealed for anyone with information to come forward.