Jackie – the beloved bald eagle at California’s Big Bear Lake whose livestream was followed by millions of viewers as she birthed and raised chicks – died on Monday due to a mysterious illness. She was 14.

Jackie had been receiving treatment at the Ojai Raptor Center since mid-July when she was found weak and unable to fly after a scuffle with two younger eagles. Experts at the center had discovered that she was suffering from severe anemia, and suspected she had been sick for weeks before the fight grounded her.

“We know this news will be deeply felt by the many thousands of people around the world who have followed her journey, hoped alongside us, prayed for her, and supported the people caring for her,” the raptor center staff wrote in an Instagram post announcing Jackie’s death. “Our team is heartbroken. It has been an extraordinary privilege to care for her. “

Despite administering a number of tests including a CT scan and bone marrow biopsy, experts at the center said they could not determine what had sickened Jackie.

The center is in consultation with the US and California fish and wildlife services about Jackie’s condition, and “will provide a more comprehensive statement including additional information on her treatments and test results” at a later date, it said.

The public had been watching Jackie’s nest since a livestream was first set up in October 2015 – it was then inhabited by her parents Ricky and Lucy. In 2018, the public watched as Jackie defended her nest against an intruder, dubbed Mr B. Then, Shadow – the male eagle who became her mate – moved in. Greater and greater numbers of viewers tuned in during the pandemic to watch the couple build their lives together and welcome several clutches of fluffy hatchlings.

In January, the couple’s clutch of two eggs was eaten by ravens. Jackie laid two more eggs in February, and thousands watched as the couple hatched their two youngest – Luna and Sandy. The latter was named after Sandy Steers, the executive director of Friends of Big Bear Valley, who had recently died from cancer.

The couple inspired the public to fight for the environment they inhabited. The Friends of Big Bear Lake launched a $10m effort to buy land near the eagles’ nest which had been slated for development – drawing support from the local elementary school, as well as from OpenAI co-founder Greg Brockman and his wife, Anna. The non-profit will now steward 63 acres of the land.

Fans of Jackie shared messages of grief following the news of her death – and celebrated her legacy of inspiring a massive public campaign for preserving natural habitat.