HUNDREDS OF BIRDS INVADE HOME IN CALIFORNIA. Hundreds of Birds Invade Woman's Home in California. Hundreds of birds swirled ''like a tornado'' down the chimney of a home twice in one week, creating a fluttering mass invasion reminiscent of the Alfred Hitchcock movie ''The Birds,'' the home's owners said today. ''They were just swarming around and around,'' said John Melton, a City Councilman in this Ventura County community north of Los Angeles. ''Then all of a sudden one went down the chimney, then they narrowed into a funnel just like a tornado and - shoomp. - right down the chimney.''. The birds were identified by ornithologists as Vaux's swifts, now migrating from their winter homes in Mexico and Central America to the Pacific Northwest. The Meltons returned last Friday from a two-day trip and discovered the tiny birds had invaded their hillside home by flying down the chimney and through an inch-wide space between the fireplace frame and screen. 'They Were Everywhere'. ''They were four deep on our 12-foot windows,'' Lucille Melton said. ''We walked through the house and they were everywhere. We estimated 800 to 1,000 birds.''. Most of the birds were gone by Saturday afternoon, Mr. Melton said, although the couple continued to find birds ''in Kleenex boxes, vases, beneath the kitchen stove, everywhere.''. As the family was preparing to go out to dinner Saturday night, a flock of about 400 swifts returned. The birds finally flew back up the chimney, and the Fire Department installed a heavy steel grate, deterring the flock when they returned a third time Sunday night. Birds Posed no Danger. In Alfred Hitchcock's 1963 film ''The Birds,'' a feathered invasion wrought havoc in a small northern California town, forcing people to abandon the community after several had been pecked to death. Ornithologists agreed that the Meltons faced no such danger from the swifts. ''They couldn't bite you, hurt you, scratch you if they had to,'' said Kimball Garrett, bird collection manager at the Los Angeles County Museum of Natural History. The birds, flying into foul weather, probably mistook the Meltons' chimney for a tree trunk, their normal roosting place, Mr. Garrett said. ''I don't know what causes them to select one chimney over the other,'' he said. ''Perhaps the shape.'' ''All I know is they're dirty birds,'' Mr. Melton said during a telephone interview. The incident was the latest of several bird invasions recently reported around Southern California. Last month in Santa Barbara, a woman and her daughter were routed from their home when scores of birds, identified as barn swallows, entered through the chimney. And Mr. Garrett said last week a woman in Santa Monica, on the coast near Los Angeles, reported that about 300 swifts had invaded her home for a night..