California wildlife researchers are currently investigating the cause of dozens of cormorant deaths in the San Francisco Bay area since mid-April. The California Department of Fish and Game (DFG) Marine Wildlife Veterinary Care and Research Center in Santa Cruz are conducting post-mortem exams to determine the potential causes of this unusual mortality event and stress that preliminary tests show there is no concern that these birds are carrying the H1N1 (swine flu) virus.

Beginning in mid-April, natural resource agencies began receiving reports of dead and dying cormorants and occasionally other coastal birds in the Bay area. Dozens of dead Brandts Cormorants were found at a nesting colony on Alcatraz Island and dozens more have since been recovered on the coast from San Francisco Bay south to Monterey.

In addition, dozens of live sick cormorants have been recovered by local wildlife rehabilitation centers. The birds have been found to be extremely emaciated.

No signs of environmental contamination or disease have been found. Preliminary results of tests for domoic acid, a natural toxin produced by marine algae that proves fatal to birds, were negative, as were tests for Newcastle Disease, Avian influenza and West Nile Virus.

Brandts Cormorants (Phalacrocorax penicillatus) are large black seabirds that occur along the California coast year-round. They typically nest in colonies on offshore rocks and islands beginning in the spring and are one of the most common nesting seabirds in California. Cormorants are not considered a special-status species, but like most native birds they are protected under the Federal Migratory Bird Treaty Act. Cormorants feed on small fish that they capture by diving from the surface of the water.

There is currently no concern regarding public health connected to this event and no need to report dead birds to wildlife agencies. The public is asked to leave dead birds where they are found. Regular surveys are being conducted by volunteer monitoring programs established by the Gulf of the Farallones and Monterey Bay National Marine Sanctuaries to document the number and location of dead birds. If very large concentrations of dead birds are found, they can be reported to DFGs Marine Wildlife Veterinary Care and Research Center at (831) 469-1745. Live birds in distress can be reported to local animal control or wildlife rehabilitation groups. If wildlife that may be oiled or otherwise contaminated is found, this information can be reported to the Oiled Wildlife Care Network at 1-877-UCD-OWCN.