WATERVILLE, Vt. (AP) – With its tidy brick farmhouse and adjacent red barn, Old Homestead Farm looks more like a New England postcard than a crime scene. But it’s one of the latest victims in a bizarre string of thefts.

Earlier this summer, someone sneaked into the farm, scaled the barn roof and stole a copper-and-zinc weather vane that had flown from the 40-foot high cupola for more than 150 years, replacing it with a cheap replica.

“You wouldn’t think there’d be any crime out here, but there is,” said Elaine Thomas, who owns the farm with husband Dennis. “I just wish he’d taken the SUV, or a bicycle or a canoe. Things we could replace.”

In a puzzling series of whodunits, weather vanes like the Thomases’ are turning up missing. More than 20 have been stolen in recent years in New England and New York.

“Those are just the reported cases,” said Sgt. John Flannigan, a spokesman for the Vermont State Police. “I just wonder how many of these may have occurred and may not have been reported to the authorities. They may not even know it.”

In the Old Homestead Farm case, police believe the thieves used climbing gear to get up to the cupola and removed the horse-shaped weather vane.

They apparently installed the replacement in hopes of duping the farm’s owners long enough for the original to be sold into an antiques market that now views weather vanes as prized pieces of American folk art.

One day in June, Thomas’ daughter noticed the antique weather vane was gone.

“I just screamed “That’s not our horse,” Elaine Thomas said. “I knew instantly.”

The value of antique weather vanes is apparently what’s driving the thefts, which have been reported in Maine, Massachusetts, Vermont, New Hampshire and New York.

A weather vane depicting a locomotive that once sat atop the Woonsocket, R.I., train station recently sold at auction for $1.2 million.

State and federal authorities in New Hampshire are investigating weather vane thefts, but it’s unclear whether they are the work of the same people responsible for any of the others.

Since January of 2005, at least three thefts have been reported in Massachusetts, one in York, Maine, and at least one in Concord, N.H., where police investigating one theft tracked it to Florida and recovered it.

Concord police are working with the U.S. Postal Inspection Service on another case involving a stolen weather vane, but officials refused to comment about, saying it was an active investigation.

Theories abound about who may be responsible.

“Is it someone who’s there to do work on a house, some kind of repair work? Or is it people who are targeting these weather vanes? That’s the mystery,” said Flannigan.

It isn’t uncommon – or easy – for thieves to erect replacements when they steal the vanes, according to antiques expert Kathy Greer, editor of Laconia, N.H.,-based “Unravel the Gavel,” an antiques newspaper.

“To put one of these weather vanes up takes more than one person. Some of them, I would guess, have to weigh a couple hundred pounds. It’s just not something you’re going to stick under your arm” and carry away, she said.

Jean Burks, senior curator of the Shelburne Museum in Shelburne, which has an extensive collection of weather vanes, said stolen ones often turn up for sale in antiques magazines. But dealers are leery about buying ones they believe may have been stolen, she said.

“It’s a pretty tight network and people are aware of what’s been stolen. It’s not going to go far. I’m sure she’ll get it back the minute it starts changing hands … to some professional dealer,” said Burks.

That’s what happened to a weather vane depicting the angel Gabriel, stolen in 2003 from the White Church in Crown Point, N.Y.

Someone brought it to folk art dealer Fred Giampietro in New Haven, Conn., who recognized it immediately. The theft remains under investigation.

Some farmers, worried about possible theft, have removed their antique weather vanes and put up replicas.

To the Thomases, who are fifth-generation farmers, the weather vane had both practical and sentimental value. The family raises Morgan horses, a breed developed in Vermont two centuries ago.

“That’s why the weather vane was so important to us,” Elaine Thomas said. “It was a Morgan. It was our logo.”