The "mystery goo" that sickened hundreds of East Bay seabirds last month contained a mixture of non-petroleum-based fats or oils, California Fish and Wildlife officials said Thursday.
State and federal agencies worked together to identify the contaminant which killed 170 birds and affected an additional 323 birds that were captured alive.
Non-petroleum oils include synthetic oils, such as silicone fluids, tung oils, and wood-derivative oils such as resin/rosin oils, CDFW said. Animal fats and oil, and edible and inedible seed oils from plants are also included.
"So far, no culprit has been identified as the party that let the oil get into the bay," said Dave Crane, environmental program manager for the Office of Spill Prevention and Response.
The gunk degraded to a sticky, thick consistency that was very difficult to remove from the feathers of affected birds, CDFW said. It ranged in consistency from an oily or gummy substance to a hard varnish, coating the birds and compromising their ability to stay warm, float, fly and locate food.
The International Bird Rescue organization cared for the birds captured alive.The number of impacted birds that may have sank, lost to predation, or missed during searches is unknown.
Besides CDFW, the agencies involved in identifying the goo include the U.S. Environmental Protection Agency, the National Oceanic Atmospheric Administration and the California Department of Public Health.
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“This was like a giant jigsaw puzzle with thousands of pieces to put together,” said OSPR environmental scientist Janna Rinderneck. “We had many possibilities of what this material could be. Working together, the laboratories have narrowed that list.”
Non-petroleum-based fats or oils that come in contact with the hair and feathers of wildlife can cause similar effects as petroleum products, including loss of thermal insulation and buoyancy.
