SAN JOSE, Costa Rica - Authorities in Costa Rica said Tuesday they are investigating the mysterious deaths of about 500 brown pelicans along the country's Pacific coast over the last five days but do not suspect bird flu was the cause.
The first dead birds were spotted by a fisherman on Thursday on San Lucas Island, about 10 miles from the coastal city of Punta Arenas. More turned up in the following days at nearby islands and rivers.
"This is a situation that is enormously worrisome," Costa Rican Environment Minister Roberto Dobles said. "But it is hard to know what happened, and so it is better not to speculate."
Investigators were collecting tissue samples from the dead birds, but tests to determine the cause of death may take several days, said National Animal Health Service spokesman Flor Aguero.