A brush fire at the Mast Landing Audubon Sanctuary in Freeport on Tuesday afternoon may have been caused by an improperly disposed cigarette butt. About 1.5 acres of the 145-acre preserve, suffered fire damage, but no individuals or properties were harmed. The forest canopy remains intact. “While no cause can officially be determined, it is suspected that an improperly disposed of cigarette butt might have been responsible. During the dry season, even the smallest ember can smolder in the duff for days until the relative humidity and winds create the perfect environment for ignition,” Maine Audubon said. The sanctuary features more than three miles of hiking trails that wind along a stream and tidal marsh and through an orchard, fields, and forest.