An additional 100 young terns washed up on the Long Beach shore Friday as wildlife experts and state officials tried to piece together why 300 were discovered dead two days earlier.
The prevailing theory is that the birds were disturbed when the barge they were nesting on was moved.
After receiving calls that more were washing ashore dead, the International Bird Rescue Research Center dispatched search teams to the beach Friday morning and to the barge where the Caspian and elegant terns had been nesting. Seven live birds were recovered and taken to the center in San Pedro, bringing to 23 the number of survivors.
The young birds could not float in the water or fly because they had not yet grown enough feathers.
"Basically, there was a second incident today," said Rebecca Dmytryk, part of the rescue team that went to the barge just south of Island White.
The barge was empty when she arrived, Dmytryk said, and a second barge, which had not been there Thursday and was carrying what appeared to be a power washer, was tied to it.
"Originally, we didn't know there were two barges out there," she said. "What we're suspecting is that one barge was cleaned off, and that's where the first babies came from. And the second barge is where today's came from."
The theory is shared by Dan Salas, owner of tour boat company Harbor Breeze Cruises, who has watched the terns daily since they started nesting two months ago on both barges. On Wednesday, the day the first batch of birds washed ashore, one boat was gone, Salas said. But it was back Friday, cleaned and tied to the remaining barge, which was almost empty of terns.
"If they would have towed the barge away, you would have had birds scattered from here to L.A. All these birds were concentrated in one area, so they had to hose them off or physically brush them off with a broom," Salas said. "There are hardly any there now."
Coast Guard Lt. j.g. Erik Sumpter confirmed that a tugboat began taking one of the barges to Santa Barbara for a fireworks display, but the Coast Guard ordered it to turn back. The barge had an invalid load line certificate and is now being investigated, he said.
Lt. Kent Smirl of the state Department of Fish and Game said the department is still trying to talk with the barges' owner, and officials would not release his name.
The birds are protected under the federal Migratory Bird Treaty Act, authorities said, and it is a misdemeanor to disturb them. Animal cruelty is a felony in California. The International Fund for Animal Welfare is offering a $10,000 reward for information leading to an arrest if the animals were intentionally disturbed.