© John Schoen A black-capped chickadee with a deformed beak in the Hillside area of Anchorage, 2010. About 7 percent of Alaska black-capped chickadees have the beak deformity, which is spreading to other birds such as ravens and crows, and to other parts of the world, including Great Britain.
When black-capped chickadees and some other birds in the Anchorage area began turning up in the late 1990s with
elongated, weirdly curved or twisted beaks, biologists and bird lovers began to worry.
The deformities range from slight to gross and can have severe consequences for the birds if they are unable to use their beaks to pick up food or groom feathers so their bodies retain heat.
"People, a lot of times when they first see them, think the bird is carrying a twig in its beak," said Colleen Handel, a U.S. Geological Survey biologist who has devoted several years to studying the problem.
The tiny black-capped chickadees are the most afflicted, with 7 percent of Alaska adults developing deformed beaks.
The deformities are also showing up in other birds, including ravens and crows, though not as frequently, Handel said.
Now the beak-deformity outbreak has spread north to Fairbanks, south to the Puget Sound region and -- for an unknown reason -- across the globe to Great Britain, where it is showing up among starlings, tits and other species, Handel said.
Comment: Map of animal events since the start of 2015 -