Guillemots have been found on beaches from Mevagissey in Cornwall to Kingsbridge in Devon.
Dozens of eider ducks, cormorants and guillemots have all been found with contaminated plumage.
The charity said the bodies of puffins, kittiwakes and guillemots had been discovered.
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But most of the species affected - guillemots, razorbills, gannets, cormorants, and some wading birds - have fairly stable populations.
More than 90 birds covered in the substance, mostly guillemots, washed up between Mevagissey in Cornwall to Kingsbridge in Devon.
More than 300 birds, mostly guillemots but also some razorbills, have been treated at the RSPCA West Hatch centre near Taunton, Somerset.
Hundreds of birds, mostly guillemots, were washed up on the south coast of England three weeks ago, covered in glue-like polyisobutene (PIB).
It is now a listed Federal Heritage Building, and the island is a protected wildlife reserve, home to breeding and nesting guillemots and razorbills.
More than 300 birds, mainly guillemots but some razorbills, were taken in by the RSPCA after being found covered in glue-like polyisobutene (PIB).
Accordion, trumpet, violins and keyboard created a euphoric Arcade Fire-party atmosphere, while fans of The Guillemots would also be taken under their spell.
In February, more than 300 birds, mainly guillemots and some razorbills, were taken in by the RSPCA after being found covered in glue-like polyisobutene.
In February, more than 300 birds, mainly guillemots and some razorbills, were taken in by the charity after being found covered in glue-like polyisobutene.
They fear that with vital catches of fish such as sand eels getting smaller, breeds like puffins and guillemots may also decline in the future.
More than 300 birds, mostly guillemots but also some auks and razorbills, have been treated at the RSPCA West Hatch centre near Taunton, Somerset, since 31 January.
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The weather has been blamed for the death of hundreds of birds, including puffins, razorbills and guillemots, in Scotland and northern England, according to the RSPB Scotland.
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.
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On Wednesday 22 guillemots were released at Pett Level beach.
The Royal Society for the Protection of Birds (RSPB) looks after the colony, which it describes as a "bustling seabird city, with puffins, black guillemots, razorbills and peregrines some of the special residents".
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