MATTAPOISETT, Mass. (AP) – Wildlife experts are using noise cannons, air horns and strobe lights to try to keep rare roseate terns from nesting on an island in Buzzards Bay fouled by an oil spill.

Ram Island, off of Mattapoisett, is home to about 1,000 pairs of roseate terns, or about 25 percent of the species in North America. It has been “very heavily oiled” and experts want to keep the birds away, said Carolyn Mostello, a wildlife biologist with the Massachusetts Division of Fisheries and Wildlife who is in charge of protecting the birds.

“We don’t want to risk losing any adults to oil,” she said.

The measures will also protect about 2,000 pairs of common terns – also rare, despite the name – who nest on the island, Mostello said.

Nearly 15,000 gallons of No. 6 fuel oil was spilled on April 27 in Buzzards Bay by a barge owned by Bouchard Transportation Co. Inc. The cause of the spill is under investigation, while Bouchard is footing the bill for the cleanup effort.

The number of cleanup workers on the shore of the bay, which is a productive area for shellfishing, reached 663 people on Sunday. The oil has washed up on 40 miles of shoreline. So far, 128 birds have been reported dead, while 79, mostly common loons, are being cared for, the Coast Guard said Sunday in a statement.

Roseate terns are little white birds with a black cap and a delicate blush of pink on their breasts.

Mostello said the oil could harm birds by reducing the insulating power of their feathers and subjecting them to hypothermia. The birds could also be harmed if they ingest the oil, she said.

The cannons, nicknamed “boomers,” are shot at night when birds are more easily spooked. Residents in nearby towns are being advised of the noise in advance.

Mostello said it wasn’t clear what the birds, who typically return to the area in late April after wintering in South America, will do if frightened off from their usual nesting spots.

“It’s going to be an experiment. We need to keep them off until it’s very clean. In the meantime, they’ll hopefully be looking for somewhere else to nest,” she said.

Nearby Bird Island is home to another 25 percent of the roseate terns in North America, but so far it hasn’t been oiled as badly as Ram Island, Mostello said.

AP-ES-05-04-03 2004EDT