Officials are still trying to identify a "mystery goo" that has affected hundreds of seabirds found along shorelines in the San Francisco Bay Area.
International Bird Rescue says 81 healthy seabirds have been returned to the wild following care and treatment at its San Francisco Bay center.
The organization says each of the birds was medically stabilized and then washed, using a combination of baking soda and vinegar, followed by cleansing with a dishwashing detergent.
The Center is still caring for 132 birds.
Another 151 birds were found dead by the California Department of Fish and Wildlife.
International Bird Rescue officials say testing of goo-covered feathers continues at government and private labs.
But so far, there is no identification of the goo, described as "gummy" and like a dirty rubber cement. Preliminary reports showed it was not a petroleum-based substance.
The Center has treated 323 birds in the past two weeks.