Bird Flu in an Uncommon Form, and the Science It Left Behind

For nearly a decade, millions of people watched Jackie the bald eagle through a livestream camera fixed on her nest in Big Bear Valley, California. They watched her lay eggs, tend to eaglets, and weather the seasons with her mate, Shadow. When she died in August at the age of 14, the loss was felt far beyond the rugged San Bernardino Mountains. But the question of why she died remained unanswered for months.

On Wednesday, the California Department of Fish and Wildlife released the results of a necropsy performed by veterinary pathologists at the San Diego Zoo Wildlife Alliance. The findings surprised even the experts who had followed her case closely. Jackie's primary cause of death was Highly Pathogenic Avian Influenza—bird flu .

What made the diagnosis unusual was how the virus presented itself. Rather than causing the typical neurological symptoms associated with avian influenza, the infection triggered a severe ulcer in Jackie's ventriculus, the muscular portion of a bird's stomach commonly called the gizzard. That ulcer led to persistent internal bleeding, severe anemia, and the development of bacterial sepsis . "In an uncommon presentation of the virus, the infection caused a severe ulcer in her stomach that led to persistent internal bleeding, anemia, and the development of bacterial sepsis," said Steve Kubiski, director of disease investigations at the San Diego Zoo Wildlife Alliance .

The necropsy also found evidence of chronic disease involving the gizzard, with damaged tissue contributing to ongoing blood loss. Testing detected genetic material from the bird flu virus in multiple tissues throughout her body, including the ulcerated stomach tissue. Additional testing ruled out West Nile virus and heavy metals as contributing factors .

Toxicology screening did detect brodifacoum, an anticoagulant rodenticide commonly known as rat poison, in Jackie's liver, along with other persistent environmental contaminants. But the necropsy found no signs of the uncontrolled bleeding typically associated with rodenticide poisoning. Brodifacoum was therefore not identified as the primary cause of illness or death .

For Dr. William Bowerman, a professor of wildlife ecology and environmental toxicology at the University of Maryland who has studied bald eagles since the 1980s, the findings were unexpected. "Nobody knew this was even a probability," he said. "Her case gave us more science than we were expecting" . Bowerman noted that there was no active outbreak of bird flu in Southern California at the time of Jackie's illness, making the diagnosis even more puzzling. The H5N1 strain had been documented killing bald eagles across the country since 2022, but widespread outbreaks had subsided by 2026 .

How Jackie contracted the virus remains a mystery. Bowerman said she may have eaten an infected duck or goose, or consumed water containing the virus. It is also possible she was exposed years earlier and the disease lay dormant until it flared .

Jackie was first taken to the Ojai Raptor Center in July after she was found on the shoreline of Big Bear Lake, unable to fly. She appeared underweight, with severe anemia and kidney inflammation. Despite a blood transfusion and weeks of care, she died on August 10 . Her remains were cremated by the U.S. Fish and Wildlife Service's National Eagle Repository to prevent the spread of bird flu .

Chris Eksteen, executive director of the Ojai Raptor Center, said the necropsy results "have helped connect many of the findings we were seeing throughout the eagle's hospitalization" . For scientists studying avian influenza and its effects on raptors, Jackie's case has provided an unusual and valuable set of data—one that may help inform future treatment and conservation efforts.

AI Image Disclaimer: This article's image is AI-generated and does not depict the actual bald eagle or necropsy procedure.

Sources: California Department of Fish and Wildlife, USA Today, Los Angeles Times, Kansas City Star, The New York Times, CBC News