Several more ducks were rescued by RSPCA staff
Around 20 birds have been rescued from an oil spill at a picnic spot in Hertfordshire.
A swan, a glebe and 15 Mallard ducks were plucked from the River Purwell in Hitchin, Hertfordshire, on Tuesday after oil spilled into the water at Walsworth Common.
Several more ducks were rescued by RSPCA staff on Wednesday and Thursday.
One inspector waded into the water and drove the animals towards colleagues who waited on the bank with nets.
Each bird was cleaned and then taken to Tiggywinkles Wildlife Hospital in Aylesbury, Buckinghamshire, where they were fed carbon to counter the damaging effects of oil they swallowed. The cause of the oil spill remains unknown.
The birds have been taken to Tiggywinkles Wildlife Hospital
RSPCA inspector Peter Green, who was among the group that rescued the birds, said: "It was quite a serious mess really. It's pretty unusual for it to be so bad.
"Even though the birds were covered in oil and in quite a bad way, they were hard to catch - we were constantly trying for at least six hours.
"It is not at all good for the birds to be covered in oil. It stops them flying and means they are not waterproof so struggle to float on water.
"The birds were constantly trying to clean off the oil also. They were exhausting themselves with the effort, plus there are all kinds of issues with them ingesting oil."