Editor's note: View a slideshow about this rescue.

UC Davis wildlife experts leading the rescue of oiled seabirds along the Southern California coast say this oil spill has been the worst worldwide for wildlife in more than two years, harming more birds than any spill since the 2002 wreck of the tanker Prestige off Spain's coast.

Since Wednesday, Jan. 12, UC Davis veterinarians, staff members and volunteers have picked up nearly 1,400 oiled birds on the coast between Santa Barbara and Huntington Beach. Of those birds, 612 were dead or so sick they were humanely killed. Oiled birds are continuing to arrive daily at the UC Davis-run rescue center in San Pedro.

Jonna Mazet, a UC Davis veterinarian and international authority on the rescue and treatment of oiled wildlife, said today that studies of previous spills and their effects have concluded that for every oiled seabird that is found washed ashore, there are about 10 to 100 birds that died at sea.

Mazet said that while 1,400 birds have been found, she estimates that at least 2,400 and possibly more than 5,000 have been oiled.

The source of the deadly oil has not been identified by state officials. But, Mazet said, "Just because you don't see a broken ship doesn't mean there aren't huge impacts on wildlife."

Still, the spill has not received much public attention -- perhaps because it began while Southern Californians were still reeling from five days of rainstorms that killed 20 people in floods and landslides.

The Oiled Bird Care and Education Center in San Pedro is one of a chain of coastal rescue centers and programs that are collectively called the Oiled Wildlife Care Network. The network is the world's most advanced system of emergency centers for wild animals hurt in oil spills.

The Oiled Wildlife Care Network is managed by the UC Davis Wildlife Health Center, which is part of the UC Davis School of Veterinary Medicine. Mazet is director of the UC Davis Wildlife Health Center.

The Wildlife Health Center is dedicated to the conservation of free-ranging wildlife through research and education. Its 10 years of veterinary care and scientific study of oiled birds, otters and other wildlife have established standards and practices now used worldwide for saving oiled animals. Using radio transmitters, the center will study the long-term survival rates of the birds being treated now.

Mazet compared this spill with the Prestige wreck off Spain's coast in November 2002, where UC Davis veterinarians also worked in the bird-rescue effort. When the Prestige sank, the single-hulled tanker leaked 63,000 tons of fuel oil. A subsequent report by Spanish scientists estimated that more than 250,000 sea birds were killed.

Yet only about 840 oiled birds were ever found, said UC Davis veterinarian Michael Ziccardi, who worked in the Prestige rescue and is now leading operations at the San Pedro bird center.

"In Spain, we recovered 508 birds alive and 320 dead in three weeks. Here in California, we have recovered that many birds in three days," said Ziccardi, who like Mazet is an international authority on the rescue and treatment of oiled wildlife.

Most of the injured birds being collected in the California spill are western grebes, which are large, striking, black-and-white birds with long, thin, yellow bills that the birds use to catch small fish in near shore waters. At this time of year, western grebes are often seen swimming along the Pacific Coast, from southeast Alaska to central Mexico.

Western grebes are listed as a California "species of special concern" because of population declines at some breeding sites.

Other oil-soaked seabirds that have been treated include Clark's grebes, eared grebes, loons, brown pelicans, and a Brandt's cormorant and a surf scoter.

The bird rescues begin at two emergency stabilization facilities managed by UC Davis -- one in the Ventura Harbor area and one at Point Mugu Naval Air Station -- and a third managed by California Wildlife Center in Malibu. Birds collected by searchers on beaches and in boats are taken there for initial treatment. Then they are driven to the oiled bird care center in San Pedro for continuing medical care.

The Oiled Wildlife Care Network is funded by the California Department of Fish and Game's Office of Spill Prevention and Response. The Fish and Game monies come from interest on the $50 million California Oil Spill Response Trust Fund, which was built from assessments on the oil industry.

While the rescue program is led by UC Davis, there are many wildlife organizations taking part. They include: Point Reyes Bird Observatory, International Bird Rescue Research Center, California Wildlife Center, Wetlands and Wildlife Care Center of Orange County, Santa Barbara Wildlife Care Network, the Marine Mammal Center at Fort MacArthur, Long Beach Aquarium of the Pacific, Wildlife Assist, Project Wildlife and SeaWorld San Diego.

More than 125 volunteers per day have been caring for the injured birds, Ziccardi said, and more help is needed. Volunteers must be age 18 or older; for information, call (800) 228-4544.

Anyone finding an oiled bird is urged not to approach it but to report its exact location by calling (562) 342-7222.