Lab tests from the California Department of Fish and Wildlife (CDFW) and other agencies have found that the "mystery goo" that turned up on hundreds of bird in the Bay in mid-January is a mixture of non-petroleum-based fats or oils. Non-petroleum oils include synthetic oils, such as silicone fluids, tung oils, and wood-derivative oils such as resin/rosin, animal fats and vegetable oils. The exact product, however, has not been determined.
More than 150 birds died with the goo on them. That's because the contaminant, ranging in consistency from an oily or gummy substance to a hard varnish, severely compromised the ability of the birds to stay warm, float, fly and locate food.
The investigation continues to identify the source of the contaminant.
PHOTOS: Release of some of the birds that were covered in "mystery goo".