New threats to the species, such as wind turbines or a bird flu strain, could threaten its long-term success. “The resilience of these animals was very close to the edge,” Dr. Schuler said. “If a few more breeding adults died, that could actually have a pretty big impact on the future growth of these populations.”
It is not yet clear how this bird flu will affect the species’ recovery. “I’m concerned it will be endemic, and there’s already been reports of some recombination, which means there’s this new strain mixing with some of the North American versions we have and creating new viruses,” Dr. Schuler said. “We always worry about those.”
But it appears the virus will harm nesting success — the ability of a nest to produce at least one young bird capable of flight — among certain populations this year, according to a statement from the Georgia Department of Natural Resources. Aerial surveys of nesting bald eagles in six coastal counties in Georgia have revealed nest success was down 30 percent this year, according to the statement.
Some wild birds infected with avian influenza can show no symptoms, but infection can also lead to neurological problems, which can make it difficult for a bird to fly or right itself. At Back to the Wild, a rehabilitation center in Ohio, bald eagles believed to have bird flu appear unsteady on their feet and are unable to fly; some have even had seizures.
“All are admitted with the same symptoms and pass away within hours of admission,” said Heather Tuttle, the director of education at the center, adding that the rate of admission has started to slow down. Of the dozen brought into the center, none have survived. There is no effective treatment.
Avian flu poses little threat to people, and no cases of H5N1 bird flu infection have been reported in the United States, according to the Centers for Disease Control and Prevention. People should avoid direct contact with wild birds and their feces, and hunters should avoid harvesting or handling wild birds that are sick or found dead. Hunters should also wash their hands with soap and water after touching game birds and cook meat to an internal temperature of 165 degrees Fahrenheit.
Some experts have advised people to take down bird feeders to reduce the spread of H5N1 in wild birds. But Dr. Schuler has not seen many birds that use feeders, such as songbirds, infected with the virus. “So it doesn’t seem like that is a major source of potential transmission,” she said.