The RSPB have published the results of its Big Garden Birdwatch.
During February more than 1,000 dead seabirds were found around the coasts of Cornwall, Devon and Dorset.
A change in wind direction could have killed thousands more birds after scores were found washed ashore along England's south coast.
Chemists at Plymouth University have identified the sticky substance that has killed hundreds of sea birds off the Devon and Dorset coast.
Their findings suggest it's a form of Poly Isol Butene, or PIB, used as a lubricating additive in oils to improve performance.
Tamsin Eames reports:
Experts have identified the chemical which has caused a pollution incident off the South West coast. It's an oil additive, known as polyisobutene. Meanwhile the RSPCA Wildlife Centre in West Hatch is continuing to deal with birds caught up in the spill. Watch Caron Bell's report.
– Peter Venn, West Hatch manager
We are incredibly grateful for donations of margarine, fish for the birds and even some food for the staff which have come in from lots of local people.
This incident was completely unexpected and came out of the blue. We were not expecting such sudden vast numbers of birds to come through our doors in need of help and we were literally running out of the margarine to clean them and fish to feed them.
It is still early days and hard to say how the birds will survive in the long-term but the margarine is proving to be a real life-saver."
Members of the public have donated margarine and fish to help seabirds which were taken to a Somerset rescue centre after being contaminated with a mystery paraffin oil.
Staff at the RSPCA's West Hatch centre in Taunton are caring for more than 300 birds which were found covered in the sticky substance along the south coast.
The birds, mainly guillemots but some of them razorbills, were found mainly on Chesil Beach, near Portland and Weymouth.
Subsequent attempts using margarine were more successful, but as the number of the birds arriving at the centre grew, supplies of the life-saving spread dwindled until members of the public stepped in to help.
Beaches in Devon and Dorset where hundreds of birds were washed up are stll be scoured.
Experts are looking out for any more Guillimots and razorbills crippled by the still unidentified sticky substance. They were found from the Isle of Wight to Cornwall, but most were found at Chesil Beach in Dorset.
Animal welfare groups are urging the Government to do all it can to catch those responsible for the spill that's threatened the lives of hundreds of birds washed up in Devon and Dorset.
The RSPB were among those to quiz the Environment Minister in Devon today. Meanwhile the fight to save the seabirds continues in Somerset. Watch John Andrews report.
The RSPB says around 400 birds in total have been rescued from along the south coast but experts are still trying to detmenine exactly what caused the pollution incident.
The charity says it highlights the need for sea birds to be given formal protection in marine conservation zones. Richard lawrence reports.
A number of birds have been found dead on Dorset's coast as the rescue operation continues.
The sea birds are covered in a mysterious substance. More than a hundred have been rescued and taken to the RSPCA centre in West Hatch where margarine and washing up liquid are being used to clean them.
RSPCA deputy chief inspector John Pollock says: "The numbers of the birds coming in have been growing and sadly there were quite a few dead birds this morning. We are still down at the beach, though, collecting and trying to save as many of them as we can."