The birds were rehabilitated at an Oiled Wildlife Care Network center in Fairfield after the vessel spilled hundreds of gallons of bunker fuel into the San Francisco Bay on Oct. 30.
The U.S. Coast Guard reported that out of 49 birds taken to the care facility, 14 died from their injuries. Ten were rehabilitated and released on Tuesday, and 14 more were released today. Twenty dead birds were collected after the spill.
Dr. Michael Ziccardi of the wildlife care network said it usually takes 10 to 14 days to rehabilitate birds that have been injured in an oil spill, but the birds that were released today were especially sensitive because the oil used by the Dubai Star irritated their skin more than usual.
Initially, Ziccardi said, the biggest threat to birds after an oil spill is hypothermia and overall shock. Birds rely on their feathers to stay warm and buoyant because the feathers trap air close to the skin and keep water out. The air heats up and insulates the body.
"Oil creates a hole in that dry suit," Ziccardi said. "Birds need to maintain a normal body temperature of 102 to 106 degrees, and they can't survive in that environment."
One of the first things the birds do to try to repair the "dry suit" is to try to remove the oil by preening the area, Ziccardi said. They can ingest large amounts of oil this way, which causes problems for almost all of the body's internal systems.
The colder the birds get, the more oil they ingest. One of the most important parts of bird rehabilitation is reaching the birds quickly and warming them up, Ziccardi said. Before they are transplanted to the rehabilitation center, the birds are warmed, hydrated and stabilized.
Then they are taken to the wildlife care network's facility, where they are documented, processed and given a full medical evaluation. Veterinarians take small blood samples to determine if the birds are anemic. The birds rest for 24 to 48 hours in a warm environment, and staff members focus on re-hydrating and nourishing them.
Once the birds have recovered from the shock of the oil spill, they are cleaned with dishwashing detergent, Ziccardi said. Each bird takes about an hour to wash.
After their waterproofing is restored and the staff observes normal behavior - such as aggregating, diving for food or avoiding predators - the birds are evaluated and released back into the wild.
Ziccardi said about 50 to 70 percent of the live birds rescued by the care network after oil spills survive.
Today's release puts the number of rehabilitated birds at just above 50 percent of those rescued after the oil spill, according to Ziccardi. The center hopes to release more next week.
The Panamanian tanker Dubai Star dumped between 400 and 800 gallons of oil into the Bay two miles south of the San Francisco-Oakland Bay Bridge. The spill, caused by a mechanical failure that occurred during a bunkering operation with a fuel barge, affected miles of shoreline in the East Bay.