People spotting bald eagles in the skies over the Boston area aren't hallucinating - there really are more of the majestic birds of prey setting up shop in the urban eastern areas of the state, experts say.
There were 51 confirmed territorial breeding bald eagle pairs in Massachusetts last year, the most since they were reintroduced to the state in 1982, said Andrew Vitz, the state Division of Fisheries and Wildlife ornithologist. That includes pairs close to Boston in the towns of Milton, Waltham, Lynnfield and Framingham, all confirmed in the past year or two.
"One of the areas of most rapid expansion has been eastern Massachusetts, which has been a great surprise," Vitz said.
The exact number of eagles in the state is probably higher, because there may be some breeding pairs scientists don't even know about, and the winter population is bolstered by eagles that make their way south looking for open water when lakes and ponds to the north ice over, Vitz said.
Social media has been buzzing with sightings of the birds, distinct because of their 7-foot wingspan and snow-white heads.
They have been spotted near the Charles River and Jamaica Pond in Boston, Spy Pond in Arlington and even the Chestnut Hill Reservoir near Boston College, where the athletic teams are known as the Eagles.
Not every sighting has been confirmed, and it's unclear whether it's the same eagle or several, but there is no doubt there are more of them around, Vitz said.
Tom Palmer was awed when he spotted a bald eagle in late January near the Neponset River on the border of Milton and Boston. When he was growing up, bald eagles, the national symbol since 1782, were so rare that they had an almost mythical quality.
"It was the first time I had ever seen an actual bald eagle, and it was right in my neighborhood," said the Milton resident who manages Willett Pond in Walpole for the Neponset River Watershed Association. "I couldn't believe it."
Bald eagles have made a huge comeback nationwide. There were less than 500 breeding pairs in the lower 48 states in 1963. By 2007, when bald eagles were taken off the endangered species list, there were about 10,000, according to federal figures.
Boston isn't the only urban area bald eagles are calling home, said Kevin McGowan, an ornithologist at the Cornell Lab of Ornithology.
"It is a fairly widespread phenomenon," he said.
They are moving to the city for a couple of reasons, the experts said.
To breed, bald eagles need two things - tall trees in which to nest, and a nearby body of water in which to hunt for their favorite food: fish. Seeing eagles in the greater Boston area is proof that the region's once notoriously polluted waterways are getting healthier.
"One of the reasons eagles disappeared from Massachusetts 100 years ago was water quality," Vitz said.
Eagles are also getting more used to humans, and humans are not shooting the birds as much, said McGowan, the Cornell scientist.
"You never get tired of seeing eagles," he said.