Birds released in Dorset four weeks after oil rescue
Rescued birds have been released at sea for the first time since being found on the south coast of England covered in an oil additive.
More than 300 guillemots and razorbills found covered in glue-like polyisobutene (PIB) four weeks ago have been cared for by the RSPCA.
Most of them were found on Dorset beaches, covered in the waxy substance.
Earlier, about two dozen birds were released from a cliff top in the Portland area.
They were the first birds released from the West Hatch Animal Rescue Centre in Taunton, Somerset.
Peter Venn, centre manager, said: "Just over 300 birds were brought in. Just over 100 had to be put to sleep.
"The substance wasn't a crude oil but it was still an oil."
Other affected birds were found in Cornwall, Folkestone and on the Isle of Wight.
The RSPCA said there have been reports of birds found covered in the same sticky substance in Ostend, Belgium.
The birds are to be individually assessed, weighed and blood tested by vets before a final decision is taken on which ones to release.
RSPCA staff used washing-up liquid and margarine to clean the birds after their rescue.
"It was a two-stage process," Mr Venn said. "The margarine, being a light oil, works as a solvent on a heavier oil.
"We have then had to wash it off. The birds then had a second wash before going through to pools."
Experts released 22 guillemots at Pett Level beach in East Sussex that had been cared for at Mallyadams Wood wildlife centre in Hastings, East Sussex, earlier this month.
Many of the birds found were dead, but inspectors and volunteers saved as many as they could and took them to Hastings in East Sussex and West Hatch Animal Rescue Centre in Taunton, Somerset.
The RSPB called for PIB, a colourless, synthetic rubber which can be released legally under certain conditions, to be reclassified and discharges outlawed.
An investigation into the source of the substance earlier in February, with the authorities unable to find the ship responsible.
The Maritime and Coastguard Agency (MCA) said it had failed to pinpoint the timeframe or location for when the material was discharged.
It said without new information it was "unlikely" the ship could be traced.