By TODD RICHMOND Associated Press

MADISON, Wis. (AP) — Ducky is dead.

The International Crane Foundation announced Monday that Ducky, an endangered female whooping crane the foundation planned to release into the wilds of Wisconsin this fall, died on Thursday after becoming infected with Highly Pathogenic Avian Influenza, a strain of avian flu.

Foundation officials said in a news release that Ducky's death marks the first time the strain has killed a whooping crane.

Only about 700 wild whooping cranes are left in North America, according to the foundation. Ducky's death translates to a 1% decline in the eastern migratory population, which stands at fewer than 70 birds.

"We are deeply saddened by the loss of Ducky," Kim Boardman, the foundation's birds curator, said in the release. "Each Whooping Crane is invaluable — not only to our organization, but to the survival of the entire species."

Ducky hatched in May and was part of the Baraboo-based foundation's breeding and reintroduction program. She was reared by foundation staff outfitted in crane costumes in an effort to prevent her from imprinting on humans, boosting her chances of survival in the wild. She was among a group of eight cranes set to be released into the Horicon National Wildlife Refuge in October.

Diana Boon, the foundation's director of conservation medicine, told The Associated Press in a telephone interview that Ducky's group has been at the refuge since August acclimating to the area and learning survival behavior. Ducky became sick early last week, becoming lethargic and stumbling before she finally died.

Boon speculated that Ducky may have come into contact with an infected bird or through environmental exposure to the HPAI virus as she explored the refuge. Wild birds, including waterfowl such as ducks, geese and swans, can carry the virus, often without showing symptoms, and shed it through feces, which in turn can contaminate water sources.

Staff at the marsh have taken to wearing personal protective equipment beneath their crane costumes and are keeping their distance from the rest of Ducky's group to avoid getting sick, but so far none of the other chicks have shown any symptoms, Boon said. Foundation staff planned to meet Monday afternoon to decide whether to go ahead with releasing them as planned.

Avian flu killed several thousand sandhill cranes in Indiana earlier this year.

The International Crane Foundation was founded in 1973. It works to protect whooping cranes around the globe through a network of experts in 50 countries.