MUSCONGAS BAY — The 102 people on the 6 p.m. boat out of New Harbor on the second to last day in July came to see puffins, which humans have been working to restore to coastal islands in Maine for 25 years.

But for one brief minute, the crowd got a look at something perhaps more remarkable: a pair of endangered roseate terns courting in the air above them.

The seabirds flew like pale angels with elegant, long and deeply cut tails. The pair wove back and forth, cutting invisible lozenges in the bright evening sky.

The roseates were heading toward Eastern Egg Rock, a treeless, 7-acre island southwest of Friendship in this bay whose Abnaki name means “good fishing place.” It’s an appropriate place for the colonial seabirds, which live on fish and come to land for the summer only to lay their eggs and wait until their young are old enough to fly on their own.

But roseate terns — along with other seabirds, including puffins, arctic and common terns, and even gulls — were driven from these islands at the turn of the last century, and nearly driven to extinction.

Mainlanders named Eastern Egg Rock for the eggs the abundant seabirds laid — terns at the rate of about two per year. The people who came took those eggs by the hundreds. The birds themselves were also valuable, with a pair of tern wings fetching 10 cents from haberdashers who fashioned them into women’s hats.

Laws passed early in this century helped boost all the seabirds’ numbers. But human populations also grew, favoring opportunistic gulls that eat everything from live fish and other birds’ young to the garbage out of mainland landfills. Laughing, herring and black-backed gulls quickly displaced the terns. By 1987 the roseate was considered in imminent peril of extinction and was placed on the federal list of endangered species.

No one knows for sure how many roseate terns once bred on Maine’s offshore islands, but the highest number recorded in Maine was approximately 275 pairs in 1931 — after the protective laws went into effect and before the gull populations soared. In 1978, those numbers had dropped to 65 pairs in Maine, with 85 percent of the U.S. population breeding on Bird Island in Buzzards Bay, Mass., and Great Gull Island in Long Island Sound.

Tern Decoys

Twenty years ago, a group of biologists working with the National Audubon Society set their sights on restoring arctic terns to Eastern Egg Rock, using techniques that were starting to show success in restoring puffins there.

Originally, during the puffin work, the scientists poisoned 50 pairs of large, black-backed gulls on the island. That drove off the rest and opened up Eastern Egg Rock for other seabirds to recolonize.

In 1978, the Audubon workers set out decoys of arctic terns to convince the live birds that the island was a good place to take a chance at breeding. By 1980, they added a solar-powered tape recorder to play arctic tern voices around the clock. Eighty pairs of arctic and common terns came to nest on the island for the first time in decades.

The birds “formed a concentric circle of nests around the speaker in the middle,” explains Stephen Kress, a research associate with the Laboratory of Ornithology at Cornell University and director of Audubon’s Seabird Restoration Program. “It really was a pretty dramatic effect.”

Kress’ crew left the decoys out and the tape running for only one more year. After that, he says, the real arctic and common terns sold the island to their kind more effectively than wood and Memorex.

The Seabird Restoration Project’s work had been directed at returning common and arctic terns, but in 1981, the endangered cousins arrived, too: One nesting pair of roseates.

“I thought this was fantastic, because we hadn’t really set out to attract roseate terns, and the roseate tern was in serious trouble in Maine,” Kress says. “It’s an important goal to try to have the historic distribution in mind and to try to create a whole community of seabirds that once lived together. I think that’s what we did by working with the life cycle of each species. But once we sort of got the ball rolling, if you will, some of the species came back on their own. Laughing gull, arctic tern and roseate tern all sort of followed the arrival of the larger numbers of common terns.”

In 1996, Eastern Egg Rock became the largest colony of roseate terns in Maine with 126 nesting pairs. By the time the project staffers closed down their research station on Eastern Egg Rock for the 1998 season on Aug. 8, the count there was 145 pairs — more than half the roughly 260 total pairs counted in Maine this year.

Kress says he now tells people to start with common terns if they want to bring back the roseates.

Egg Rock Hilton

The humans that inhabit Eastern Egg Rock for the summer live in a handful of tents around a small cabin that staffers call the Egg Rock Hilton. There’s a composting outhouse the laughing gulls like to perch on, and the staff and volunteers cook indoors. But washing of both dishes and people occurs out in the open, turning the participants into targets for the birds that have reclaimed the rock.

The island is officially protected by the state as the Allan D. Cruikshank Wildlife Sanctuary and maintained by the National Audubon Society. That fact is proclaimed by a red sign on the north side, facing the mainland, as well as a small plaque that leans against a beam on the porch.

Closer to the shore, a dozen guillemots sit on a dark, wet rock by another sign, this one small and yellow, that reads: “Don’t land during nesting.”

Protecting the sanctuary from unauthorized foot traffic is part of what the staff and volunteers do. A casual walk along the rocks ringing the island’s weedy interior turns up tiny eggs in crevices where a foot could easily land — wiping out a bird family’s next generation.

The workers also disrupt the nests of the largest gulls — herring and black-backed — that otherwise would displace or eat the eggs and chicks of terns and puffins. They count nests, eggs, chicks and feedings. They keep track of the baby birds that live and the ones that die.

At the end of July, four people were living on Eastern Egg Rock for periods ranging from weeks to months. Rose Borzik, the project’s assistant director, and Terry Goodhue of Vinalhaven, the island supervisor, are the two staff people on the island. Goodhue is the camp’s head counselor, there for the whole summer and responsible for keeping the books straight and the volunteers educated.

Walter Reiter, a 40-year-old student at Cincinnati Bible College, didn’t plan to spend more than a week on a 7-acre island when he came to Maine on an Audubon tour with his father earlier this summer. But he was hooked as soon as he saw the work firsthand, and offered Borzik his photography skills for a chance to spend time with the birds. Nancy Jones of Warren learned of the project through her work teaching fourth- through sixth-graders in nearby Friendship, and came to Eastern Egg Rock for eight days.

Goodhue has spent the whole summer watching the chicks from hatchling to fledgling, many of them fighting valiantly against overwhelming odds. “They’re so cute, and then they die.”

Goodhue consoles himself with the big picture: Terns can live for 20 years or more, and all a pair needs is two successful fledglings to replace themselves. “We just want to make sure that their habitat is protected,” he says. “Because if they don’t have a chance to reproduce, they’re doomed.”

North side of East Egg

Of the terns on Eastern Egg Rock, roseate adults are the palest: white bodies tinged with silver and punctuated by long red legs, a black crown and a predominantly black beak with a sliver of scarlet at its base. At rest on the rocks, their long tail feathers extend far back beyond their folded wings. In the air, their tails form a deeply cut V.

Common terns have darker wings and more red in their beaks, and arctic terns have fully red beaks and a belly smudged the color of smoke.

Roseate fledglings are also paler than their other contemporaries, but like most of the young seabirds on Eastern Egg Rock they come in camouflaging shades of white and brown rather than the adult colors of black, white and gray.

Their backs bear a distinctive scalloped pattern from the bands of pale brown outlined in white at the end of their feathers. Unlike any of the other fledgling terns on the island, their legs and beaks are a shade of faded charcoal.

Most of the roseates on Eastern Egg Rock live in their own neighborhood on the island’s north side. Humans watch the goings on from a blind the size of a short telephone booth. It’s made of wood covered with frayed and faded burlap, the color of a young roseate’s back. Inside is a red floating seat cushion resting on an overturned 5-gallon bucket. One observer at a time can sit quietly, looking out through flaps in the burlap walls.

Two of the roseate fledglings, or fledgers as the island staffers call them, apparently took a bath in one of the algae-filled pools in the rocks. Goodhue amusedly describes them as mildly naughty small children — they’ve made themselves filthy.

Another roseate fledger, just fed, bounces from rock to rock, testing its wings for the short hop in between. All at once, three roseate adults bring home the fishy, silvery bacon to their children, the 4:30 p.m. beginnings of an avian rush hour.

The cacophany is constant, music in a modern, discordant sense. Like children in a playground, the birds’ voices are high-pitched and rhythmic. On the last day of July, their sounds are occasionally punctuated by small waves breaking on the rocks.

One day later, on the first of August, the sound level seems to have dropped off by half and it’s clear that the annual exodus to the tropics has begun.

Bullies and commandos

The biggest threat to the roseates’ habitat is that it will be filled by gulls. Like schoolyard bullies, gangs of laughing gulls mob single terns flying with fish for their offspring. The strategy is to scare the smaller birds into dropping their catch, which the gulls then lunge for. It usually works.

Common terns, in their turn, will also harass larger birds in an effort to drive them away from vulnerable eggs, chicks and fledglings. A lone common tern swoops back and forth like a pendulum, engaging beaks with the herring gull standing alone on a rock.

A pair of common terns light off like small commando fighter planes on an emergency mission. They turn aside two great blue herons that are flying obliviously toward the island. The young herons break their stride as the terns rush them, make a sharp turn and head almost directly back toward wherever they came from. One tern remains airborne to encourage the interlopers not to look back.

“Terns are one of the more aggressive when it comes to chasing away predators,” Goodhue observes. He should know, having spent most of the summer wearing two layers of cardboard under his baseball cap to protect himself from the sharp bills of the common terns.

“A week ago you couldn’t do dishes outside without getting divebombed,” he said, to the nods of volunteers. This place is about birds, not people.

But the aggressors weren’t the roseates, he says. “The roseates are very well-mannered.”

A new balance

It’s not surprising that the endangered roseates put themselves on land only where they can be surrounded by greater numbers of their commando cousins — and, in a reversal of history, with the help of humans.

The return of roseates at Eastern Egg Rock and at Stratton Island, south of Prouts Neck, is more than just a tale of a species coming back from the brink. It’s also a story about restoring a community of species, not just one at a time. It’s a story about the role that humans must play for the foreseeable future.

Kress says human presence will be needed on Eastern Egg Rock and Stratton Island as long as humans keep feeding gulls from landfills or discarded fish from lobster traps. Until humans can eliminate those food sources for their gulls, he says, some will have to continue to break up gull nests to make room for terns.

One black-backed gull left on the west side of the island until early June was enough to leave that area completely devoid of terns, Kress aid. “That one gull had displaced probably 200-300 pairs of terns. … We think they moved elsewhere on Eastern Egg Rock, however they moved to where the gulls were not. If there were more gulls, there would be no place for [terns] to nest.”

Kress acknowledges that maintaining a human presence on Eastern Egg Rock “doesn’t fit our vision of the balance of nature. But that balance has been rudely shaken by the large human population on the coast and the lifestyles that we all live with and participate in.”