The birds were coated in thick oil, which officials believed was probably discharged by a tanker as it passed Estonia last week.
Estonian President Arnold Ruutel today visited the scene and urged the authorities to better monitor passing sea traffic and punish the crews of polluting vessels.
A long oil slick was first noticed off the coast of the Baltic state on 28 January.
Since then, rescuers and volunteers have been cleaning oil-coated birds, and gathering up dead birds to avoid them being eaten by other animals.
Many of the dead birds are out at sea, on thin ice, making the work difficult and dangerous.
(AFP)