BRUNETE, Spain » In the worldwide battle to get dog owners to clean up after their pets, enter Brunete, a middle-class suburb of Madrid that is fed up with dirty parks and sidewalks.

Some cities hand out steep fines. But in these tough economic times, the mayor here, Borja Gutiirrez, didn’t much like that idea. Instead, this town engaged a small army of volunteers to bag it, box it and send it back to its owners.

"It’s your dog, it’s your dog poop," Gutiirrez said. "We are just returning it to you."

Until now, Brunete’s claim to fame, if it had one, was that it sustained heavy damage in the Spanish Civil War. But these days this leafy hamlet has made headlines all over Spain. Residents say that strangers take note when they say they live in Brunete.

At a recent political event, Gutiirrez said, the mayor of Madrid sought him out.

"She said, ‘Well, it is not many mayors who think sending dog poop to voters is a good idea,’" Gutiirrez said. "’How did you dare?’"

Gutiirrez shrugged. After nearly two years in office, he said, he had visited with some 220 citizens in their homes, and the subject of dog owners was the one constant complaint. As spring approached this year, when children started going to the parks again, he decided to try what many here are calling "direct marketing."

The dog owners got their packages — white boxes bearing the seal of this town and labeled "lost and found" — within hours.

Signing for the curious parcels, they must have been intrigued, though surely unsuspecting.

So far, the boxes seem to be extremely effective compared with Brunete’s earlier campaign, which involved a remote-control specimen (very lifelike) that was used around town to get people’s attention. It followed. It banged into shoes. And it generally drew laughs. There was some improvement in behavior. But it did not last long.

Delivering 147 boxes of the real stuff seems to have produced a far more lasting effect in this town of about 10,000 residents. The mayor guesses a 70 percent improvement even now, several months after the two-week campaign.

A casual inspection of the town park near city hall seemed to support his claim. Dog owners without exception were carrying plastic bags – a sight that is still extremely rare across Spain. Most of the owners seemed to find the lost-and-found campaign funny.

"I would laugh if it happened to me," said Anahi Fidalgo, who, bag in hand, was walking his Shih Tzu, Coco. "I would be ashamed, but I would laugh."

Not all dog owners agreed with him.

The sting operation worked like this: Volunteers were instructed to watch for negligent dog owners and then to approach their dogs to pet them. After a few flattering remarks about the beauty of said dog, they asked what breed it was. Then they asked the dog’s name.

Back at city hall, where more than 500 residents have their pets registered, that was enough information to get to an address.

No one has yet publicly admitted to receiving a package. But these days asking a dog’s name in Brunete is likely to earn you a hard look. One woman walking her dog (it looked like a beagle) refused to give both her name and the dog’s.

"There is a campaign against dogs in this town, and what has this dog ever done?" she said. The woman said emphatically that she had always picked up after the dog. Of course, everybody interviewed insisted the same.

Yet Ignacio Serra, 21, who was the only volunteer willing to talk to a reporter, largely because he does not live here, said it was easy to find owners who turned their backs on their dog’s business. He collected six poops himself, he said, which he found "pretty disgusting."

Still, he said, his first undercover assignment (he popped an imaginary collar for effect) had made him laugh. "I thought it was very funny, and I had nothing else to do that day," he said.

Nowadays, he said, his friends sometimes refer to him as "the Poop Hunter."

For two weeks, no one complained, the mayor said. But then he got a few calls. Some people who had been sent the boxes said that city hall had gone out of its way to humiliate them. The mayor said that pretty much everyone in town knew who had gotten a box. He himself could not resist a peek at the list.

The idea for the lost-and-found campaign was not actually his. It came from the advertising agency McCann Erickson. The mayor said his brother, a professor, had students who were interns at the agency last year and did the remote-control poop campaign. This year, the mayor went back to McCann looking for something more "aggressive."

At first, Ricardo Rovira, who was part of the design team at the agency, worried that the mayor would not have the courage to go ahead with its direct marketing idea. But he did. McCann also made an amusing public awareness video, produced by Juan Josi Ocio, largely using actors. It was shown around town before concerts and community meetings.

And, as it turns out, the effort was good for business. "We have gotten some very serious clients because of this campaign," Rovira said.

Guttiirez is not really hopeful that the good behavior will last, though. He is working on ideas for next year. But he won’t discuss them.