California Department of Fish and Wildlife (CDFW) officials said that an unidentified sticky substance has killed around 200 birds and more than 250 birds are receiving care.

CDFW spokesman Andrew Hughan said that out of the aquatic birds that have died due to the sticky substance, around 150 of them are at a freezing facility in Hayward and 47 have been taken to the nonprofit International Bird Rescue's Fairfield facility.

The ones that are at the Hayward facility will be taken to the Fairfield center. Tests have been carried out and from them it has been found that the non-petroleum based substance breaks down the birds' feather structure. This factor does not allow them to regulate their body temperature in the freezing temperatures of Bay waters and it causes them to suffer hypothermia or death.

International Bird Rescue executive director Barbara Callahan said that the organization has admitted 301 birds at its Fairfield center. "We're heartbroken about them but we can't rescue them all", said Hughan.

Hughan advised the public not pick up any contaminated birds as they are quite weak and dying any disturbance can lead to further damage. Recent tests have confirmed that the sticky substance is not polyisobutylene.