At least 71 bald eagles were counted in Massachusetts this month during a statewide survey of the bird, which is an endangered species in the state.
Most of the eagles were spotted at the Quabbin Reservoir in western Massachusetts. But they also were seen closer to Boston, including one at the Mystic Lakes in Arlington and another on the frozen Charles River near the Museum of Science.
Tom French, who runs the state's endangered species program at MassWildlife, says the return of eagles has been slow since they started dying out in Massachusetts a century ago.
"But in these last, let's say, five years, the rate of increase has dramatically gone up," French said.
"We haven't gone a year in the last five or six or seven without having a new nest discovered. We're up to 27 nesting pairs now, from zero in the early 1980s. So they're doing great. They're doing wonderful."
The survey is done each winter to monitor the size and health of local eagle populations. From both the ground and in an aerial survey, wildlife officials and volunteers tally the birds using binoculars and spotting scopes.
Last year, a record number of eagles — 81 — was counted.
French said the actual number of eagles statewide now is most likely higher than 71 because visibility was poor when this month's survey took place. And he said the count could increase in the next week or so as additional data trickle in.
"We know the number is going to vary from one year to the next based on the weather," French explained.
"The colder we have the winter, the more bald eagles we'll actually see, interestingly, because it's freezing out birds that are up in Canada and northern Maine and completely closing them out of their food source. And those birds are forced to move further south."
Eagles were also spotted this month in Carver, Fall River, the Lakeville/Middleborough area, Pittsfield, Plymouth and Sandisfield.
The bald eagle was delisted from federal threatened status in 2007 but remains on the Massachusetts endangered list. An eagle restoration project was launched in the state in 1982.
This program aired on January 13, 2010. The audio for this program is not available.