Birders sticking beaks in

Mike Beath of Brighton, his telescope pointed out at the North Pool on the Parker River National Wildlife Refuge, had come north with his girlfriend to watch birds on a recent Sunday. He said he generally comes to Plum Island during the winter, spring, or fall, when there is no congestion from beach traffic, and a different variety of birds. What has brought him, and ''at least 50" of his friends, at various times in recent weeks is the sighting of rare bird species at this freshwater marsh.

''I've just seen bitterns and king rails," he said. ''Those are amazing birds to me."

The arrival of these birds, which have not been seen here in recent years, is providing a new impetus for a group of birders who are challenging the refuge managers over a proposal to change this 100-acre, man-made freshwater marsh, turning it back into a saltwater marsh.

The refuge managers (part of the US Fish & Wildlife Service) say the plan is only being studied, but that has not stopped a group of birders -- many of whom have close ties with the refuge -- from banding together in hopes of influencing the final decision. The 4,662-acre Parker River National Wildlife Refuge is on Plum Island, and situated in Newbury, Rowley, and Ipswich. The island is made up of those three towns and Newburyport.

''This pool adds a biological diversity to the refuge and to this area that having just salt marsh doesn't," said Rick Heil of Peabody, a member of the Committee to Save the North Pool. ''Adding another 100 acres of salt marsh to a site where you have 10,000 acres of salt marsh surrounding is of little or no value. But having a 100-acre freshwater marsh here, with all these state-listed species, has immense value."

Heil said he has opposed the plan since he first heard that it was being considered two years ago. ''These species have a history of coming and going from sites," he said. ''They're ephemeral. They'll be here for X number of years, they'll disappear for X number of years, they'll come back when conditions improve. This is well known with marsh birds at other sites. They come and go."

This spring and summer, bird watchers have spotted five state-listed species that are ''endangered," ''threatened," or ''of special concern," and they have taken their argument not just to the US Fish & Wildlife Service, but also to the state Division of Fisheries and Wildlife and to other birders on the Massbird.Org website. The rare birds, some of which were breeding, include the American bittern, least bittern, northern harrier, king rail, and common moorhen, which are protected by both the Massachusetts Endangered Species Act and the Massachusetts Wetlands Protection Act.

''This is a new thing for us to consider," said Nancy Pau, assistant manager for the refuge. ''These haven't been seen in the North Pool in over a decade. Part of our decision would be to figure out if the birds will come back year after year."

The North Pool until last year was considered ''degraded," similar to occurrences elsewhere in the US Fish & Wildlife system, Pau said, where man-made management areas became degraded after initial years of success. Stagnant water and the proliferation of invasive plants ''degraded" the habitat, and the number of marsh bird sightings declined. In recent years, management efforts have cut down on the amount of purple loosestrife, one of the invasive plants.

She said the idea to breach the dike and allow tidal flow to restore the saltwater marsh, instead of trying to keep the freshwater marsh, came after exhaustive study on how to restore the ecological health of the area. ''As an agency, we're trying to move away from intensive management to more biological management, where things take care of themselves," she said, adding that the goal is not always practical.

The North Pool is one of three freshwater impoundments the refuge created in the early 1950s by building a 1.5-mile berm in the salt marsh, according to the refuge's website, which stated that the original purpose was to create a breeding habitat for the American black duck and other waterfowl. But waterfowl breeding did not increase significantly, the site states. With no freshwater source other than rainfall, and needing to cut back on vegetation such as purple loosestrife and Phragmites australis (the common reed), staff spend a lot of time managing that area, while ''wildlife use in the North Pool was low compared with the other two" freshwater marsh areas, according to the site.

''It was a tremendous success for these marsh birds for 30-plus years," Heil said, although it never attracted black duck in significant numbers. ''Then the pool did start to decline, and many of these birds started to disappear." This year, for the first year in many, the birds have returned. Exactly why remains a mystery, Pau said.

''Suddenly populations of these state-listed rare marsh birds have shown up again," Heil said. Harrier, another state-listed protected species, also has been breeding in the marsh since 2002. ''There may have been a few sightings here and there over the past 15 years [of the other rare birds] but certainly they have not been here to the degree that they have this year."

While there are nine members on the committee, Heil said he has received about 100 e-mails supporting his position, and none favoring the proposal to restore the area as a saltwater marsh. Added Tom Carrolan, another member of the North Pool committee, ''Hundreds of people on Massbird are waiting to hear what we'd like them to do."

Pau said that there is a meeting scheduled for July 19 to determine what, if any, changes to make in marsh management. The feasibility study is nearly complete, she said, and managers are awaiting the result of a model to predict how the vegetation will react if the area is restored to a saltwater marsh. If there is a decision to change, she said, the refuge will go through a federally mandated process, including public meetings.

She admitted to being surprised by the intensity of the birders' concern. ''We've stressed many times over that no decision has been made," she said.

Taber Allison, Massachusetts Audubon's vice president of Conservation Science and Ecological Management, said his organization has not taken a position on the refuge's plan at this time, and noted that the refuge has yet to make a formal proposal.

''That's not saying we haven't been paying close attention," he said. ''We're very concerned, in general, with protecting the birds of Massachusetts and concerned about maintaining habitat for birds. Because some of these tend to be rare and may be declining, and in this area they may be breeding successfully, we're concerned about any proposal that might reduce that habitat."

The birders are promising vigilance. ''[The refuge managers] maintain it's all a feasibility study, yet from everything I've seen, they seem to be going full-steam ahead on this project," Carrolan said.