They gather in gangs in Rochester's Central Park, they hide in the shadows and caw at the moon. They bother tourists and cancer patients and downtown businesses. They poop on your car.

Rochester has some unwelcome guests, as many as 20,000 to 30,000 crows that come in from surrounding cornfields at dusk and wreak havoc -- raucous thugs looking for trouble.

The city has twice this winter hired experts to chase them off. They tried lasers and bullhorns -- hey, get out of here, you crows -- and even employed raptors to pick them off, one by one. That worked, for awhile.

But crows are the zombies of the bird world. You kill them off and they just come back, over and over.

Last week there was talk of somehow catching them up in giant nets and -- I'm not making this up -- driving them to western Minnesota where I guess they would become Worthington's problem.

So far as I know, no one has yet suggested giving the crows bus tickets to Chicago.

The citizenry of Rochester has responded with solutions both earnest and sarcastic.

"I like the idea of a bird limo to South Dakota," wrote one person on the Rochester Post-Bulletin website.

"I think a downtown Crowtel is a much better idea," wrote another.

One person has proposed a voluntary "crow militia" of six to 12 people in each ward trained to shoo crows away each night between 4 and 7 p.m.

There was even talk of mob-style crow hits, in which they would kill crows and hang them in trees as a subtle warning that Rochester does not welcome their ilk, if you know what I mean.

"That's an urban myth," said Steve Duffy, a co-owner of U.S. Bird Abatement Services, which has contracted with Rochester to get rid of the crows. "That doesn't work in a big roosting area."

"I saw someone put a fake owl up on one building," said Duffy, chuckling. "I have a picture of about 600 crows on that building, including two sitting on the owl."

Another person had put a "squawk box" on top of the building that featured the cries of hawks. But it also had chirps from other birds, which would actually attract crows.

"Good-meaning people," said Duffy, a biologist. "But clueless."

Duffy isn't sure why Rochester has such a bad crow problem; probably a confluence of many bird-friendly conditions that has also made it a magnet for geese. He's seen worse cases, but called Rochester's situation "hideous."

"I've seen cars where you can't get into them without getting it all over you," said Duffy.

The city has spent more than $8,000 in the past couple of months trying to persuade the crows to hit the hot-and-dusty. The Mayo Clinic has pitched in an untold amount of money because patients and their families have to negotiate sidewalks slick with crow droppings. Last week's newspaper featured photos of workers hosing down and power-sweeping the downtown.

Duffy's team had been let go Tuesday when I talked to him because the city had decided to handle the problem itself. "Good luck," Duffy said. "Crows are smarter than most of the people who are trying to get rid of them."

He called back later to say Rochester would be hiring them back for an ice sculpture event so "people don't get shat on."

Duffy said that "raptors are the answer," and that his team had good luck with them in December. He's told the Rochester City Council that it's more difficult to kill all the crows than it is use raptors to re-train them to go elsewhere, which he said could take three years. The crow whisperer.

Denny Hanson, city council president, said he's gotten a lot of grief over the birds. "I kind of look like William Shatner, Denny Crain on 'Boston Legal,'" said Hanson. "So people call me Denny Crow."

Laws prevent the city from poisoning the crows and from taking them across the border, "so we can't bring them to Iowa."

Hanson has been talking to local hunters about forming a posse and meeting the crows at the edge of the border and shooting them as they try to enter town, like in the movie "The Magnificent Seven."

"We've been talking about maybe putting on bounty on their heads," said Hanson. "It's truly a mess." • 612-673-1702