The light crude spilling from the Braer is highly toxic - the vapours corrode the lung linings and the ingested liquid attacks the gut. For the rescuers from wildlife groups walking the beach, it was a depressing and frustrating experience. The Royal Society for the Protection of Birds said 10,000 seabirds on eastern Shetland were at immediate risk.
The lightly oiled birds would fly off in fear and plunge back into the water, worsening their condition. But Scotland's only specialised bird de-oiling centre near Inverkeithing, Fife, was preparing to receive up to 30 survivors airfreighted down from Sumburgh, each in a cardboard cat box. Angus Cruikshank, the centre's assistant manager, said the birds would be put in warm, dark surroundings to cut stress. Their beaks are tied closed, to prevent them preening themselves and ingesting more oil.
For the first five days they are force fed a special diet of sugars and salts dissolved in water to rehydrate them, and charcoal to absorb the poison in their stomach and intestines. If, after that, they show signs of recovering their strength they are given a thorough scrubbing lasting up to three hours to remove the oil from their plumage. The birds then take a swim in one of several pools. If they fail to float, they have to be scrubbed again.
If the cure works, the birds should be ready for release into the wild in a fortnight. The centre, run by Scottish SPCA, the animal protection charity, has only three full-time staff, but can call on the help of dozens of volunteers.
At the most, it can shelter up to 300 birds. There may soon be a full house. The first consignment from Shetland was expected to include eider and long-tailed ducks and guillemots.
Back at Sumburgh, volunteers picking birds off the beaches have to be cruel to be kind. Those with no hope of survival are killed with an injection. The casualties so far are mainly black guillemots, shags and long-tailed ducks, but there have also been two of the rarer great northern divers.