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Bald eagles enjoying resurgence in N.H.

  • A mature bald eagle flies along the Merrimack River in Bow, N.H., on Feb. 22, 2014. (Geoffrey Niswander photograph)

    A mature bald eagle flies along the Merrimack River in Bow, N.H., on Feb. 22, 2014. (Geoffrey Niswander photograph)

  • A mature bald eagle flies along the Merrimack River in Bow, N.H., on Feb. 22, 2014. (Geoffrey Niswander photograph)

Concord — Geoffrey Niswander has seen the iconic white-and-brown plumage of the American bald eagle on Manchester Street in Concord, at Turkey Pond and while driving on Interstate 93.

“I have literally seen adult bald eagles 50 feet above the light posts at Shaw’s on Fort Eddy Road,” said Niswander, a Warner resident. “They were soaring around the parking lot for 10 minutes.”

A decade ago, the sight of a bald eagle in Concord would have been unheard of, but the population is enjoying a resurgence, buoyed by the banning of a pesticide and protection offered under the federal Endangered Species Act.

During a January bald eagle count, volunteers with New Hampshire Audubon set a new state record. On Jan. 12, they counted 67 eagles in five regions, the most in one day in the event’s 30-year history. The previous high was 61, which had been recorded three times since 2008. Between Jan. 1 and Jan. 15 volunteers counted 83 birds, one shy of the state record for the annual two-week watch.

“The bird is finally almost fully recovered from a real depressed population back in the 1970s,” said Chris Martin, a senior biologist and predatory bird specialist with New Hampshire Audubon.

The society partners with the state Fish and Game Department to monitor bald eagle numbers and distribution throughout New Hampshire as part of Fish and Game’s Nongame and Endangered Wildlife Program. The society provides volunteers for the monitoring.

Based on the annual mid-winter counts, the number of bald eagles in the state has doubled every decade since 1983, when volunteers tallied only seven birds. In 1993, 21 eagles were recorded. Ten years later, 40 birds were spotted. While the numbers aren’t definitive, organizers use a consistent number of volunteers to check the same areas at the same time of year.

“I’m not saying there are exactly 67 bald eagles in New Hampshire. There are clearly more than that,” Martin said. “But by using the same method every year, we see where the numbers are going, which reflects the population throughout New England is recovering and growing in a big-picture way.”

Bald eagles were removed from the federal list of threatened and endangered species in 2007. The next year, New Hampshire Fish and Game upgraded the bird’s status from endangered to threatened.

“Endangered means they are at risk of disappearing from the state altogether. Threatened means they are in danger of becoming endangered,” said Michael Marchand, a wildlife biologist with Fish and Game. “We’re so curious whether this is going to continue at the same rate. At some point in time it will have to level off once they’ve reached some kind of capacity.”

The Environmental Protection Agency took a critical step toward rebuilding the population in 1972 when it banned DDT, a common pesticide. “It was keeping birds of prey from getting enough calcium on the shells of their eggs,” Martin said. “That was obviously a critical step.”

Without the calcium, the shells were thin and brittle and susceptible to cracking, which killed the embryos.

Habitat protection under the Endangered Species Act has also fostered the resurgence.

Eagles usually nest near open water and roost in tall pines, ideal for spotting prey and providing shelter. Continued protection of the natural habitat is important to continue population growth.

“We don’t want to build up our river shores and eliminate the areas they need in the winter, and these roost sites that they need,” Martin said. “It’s about continued protection of wildlife habitat associated with waterways.”

A thriving population of bald eagles is important for scientists, who rely on the predator for information related to the state’s environment.

“The bald eagle is a sentinel in that it tells us the quality of an environment and the contaminants that might be in it,” Martin said.