The eagles are raising newly hatched chicks for the second consecutive year in a nest on a bluff by the post office.
And for the second consecutive year, they have been trying to chase off people -- apparently unaware that the Postal Service uses a stylized eagle as its logo.
Two people were attacked last week, and one of the eagles swooped down on a patron on Monday, Alaska State Wildlife Troopers spokesman Sergeant Robin Morrisett said.
One of the eagles managed to scratch up its victim, said Morrisett, who is based on Unalaska Island. "I guess it actually drew blood," he said.
Authorities have posted signs and advised people to be careful about their surroundings, but there are no plans to move the nests or fight back against the eagles, he said.
Bald eagles have a history of confronting people at the post office and elsewhere on the island, Morrisett said, adding that recently an eagle swooped very close to him before returning to its nest.
"It had a fish in its talons," he said.
Bald eagles have never been protected in Alaska under the Endangered Species Act because their populations here have been too healthy to warrant listing.
But, as the national bird of the United States, they are protected under special federal laws.
"It's extremely difficult, unless there's clear danger to human life, to move a nest while it's still occupied," said Bruce Woods, an Anchorage-based spokesman for the Fish and Wildlife Service.
The behavior in Dutch Harbor is typical of the species, Woods said. Bald eagles tend to be very protective of their young until chicks are able to fly, a milestone generally accomplished at the end of the summer, he said.
There is not much that residents can do about overly bold bald eagles other than to post warning signs, take steps to avoid the fierce birds and wear hats, Woods said.