Date: 5/11/26 8:07 am From: 'PAUL ROBERTS' via Arlington Birds <arlingtonbirds...> Subject: [Arlington Birds] Bird Flu, especially with regard to raptors
The Spring 2026 issue of Bird Conservation, by the American Bird Conservancy, has an excellent article on Bird Flu in the Wild by Deanna Altomara. The article provides an overview of the origins and spread of the flu, noting its effect on some of our largest and most iconic species, including raptors. I'd heard reports of significant die-offs of Bald Eagles in Florida, Georgia and Maineover the past two years, but nothing very specific. It's difficult to accurately measure mortality in most wild birds. One of the simplest indicators is the status of breeding populations where nests can be quantified. Altomara notes that coastal populations of Peregrine Falcon "have plummeted for the first time since the 1960s and '70s, when the bird was nearly wiped out by the use of the pesticide DDT." She reports that the breeding population of Peregrine Falcons in the San Francisco Bay Area has declined by roughly 67% between 2022-2025. (Separately, I know the Center for Conservation Biology reports that in the Delarmva Peninsula in 2025 13 of 18 adults identified during the 2024 breeding season were absent in 2025. 12 of 17 adults seen in 2023 were absent in 2024. The average annual adult loss was only 16.2% in seven years prior to 2023.) Peregrines are particularly vulnerable because they can feed on flu-infected birds that migrate through or winter in their territories. Altomara reports that more than 130 dead Peregrines tested positive for the flu since 2022, which is clearly an underestimate as many carcasses of dead falcons are never recovered. High virus detection rates also have been found in White-tailed and Bald Eagles, Great Horned Owl, Red-tailed and Rough-legged Hawks, and Gyrfalcon. Very recently a significant portion of the Conowingp Reservoir in Maryland, hosting perhaps the largest Bald Eagle population in the eastern U.S. has been closed to the public because of avian influenza. In the U.S., the bird flu has sickened about 70 people, two of whom died, but the virus is currently considered a low threat to humans. (Most of the illness has been with humans who work with commercial fowl.) In 2023, about 20 of roughly 560 California Condors were killed by the virus. "Desperate scientists tested a vaccine in Black Vultures," which proved effective. Over 200 free-flying and captive condors have been successfully vaccinated. The article reports recent significant die-offs of wildlife. In 2025 67,000 geese were claimed by the virus at a refuge in Kansas. 50,000 Eared Grebes died on the Great Salt Lake, and 1500 Sandhill Cranes died in Indiana. Earlier this year over 16,000 Canada Geese died of the flu in New Jersey. The flu is constantly evolving and different species are responding differently. Some species are developing antibodies with infected individuals often asymptomatic. Generally, people are advised not to come into direct contact with dead birds because the virus might be contagious to individuals or passed on to other wildlife (including dogs.) If you find a dead raptor or a number of dead waterfowl notify your local Animal Control Officer or Mass Wildlife. Typically wildlife agencies will not collect or test passerines or waterfowl for the virus unless a significant number of dead birds are found together, as in Kansas, Utah and New Jersey. Best, Paul Paul M. Roberts Medford, MA <phawk254...>
