The Wetlands & Wildlife Care Center posted photos of the pills and birds. The post said a person noticed hundreds of pills all over the grass at a park in Huntington Beach Wednesday afternoon.
That person then found the goose not far from the area and it appeared to be in distress. The person called animal control and said other birds may have swallowed the pills but were able to fly away.
The care center is treating the goose and a ring-billed gull that both showed symptoms of ingesting the pills. Those symptoms included loss of muscle control.
Both birds were given IV fluids that helped flush out the toxins. The center said the birds are doing fine.
Lisa Perrone, the center's wildlife manager, says that without treatment it's likely the birds would have died, if not from overdoses than from an inability to flee predators.
Police say the pills apparently included sedatives and they're grateful no children mistook the pills for candy and ate them. Police are investigating.
The Associated Press contributed to this report.