The days when Venice tolerated tourists feeding pigeons in St. Mark's Square are over.

Starting on Wednesday, it's illegal.

The sale and distribution of grain to feed the birds is now banned, ending a tradition that attracted pigeons, and their droppings, to the most picturesque part of the lagoon city.

Fines for ignoring the ban start at 50 euros ($78), the mayor's office said.

The vendors who sold grain to the tourists are now out of a job. "Thanks Mr. Mayor for killing off our business after 100 years of sales," read one banner.

Authorities say pigeons are eating away at the city's marble statues and buildings by pecking at small gaps in the facades to reach for scraps of food that were blown inside.

Cleaning up monuments and repairing the damage caused by pigeons cost each Venetian taxpayer 275 euros a year, one study estimated.

"The monuments aren't being damaged by the bird droppings. They want to send them away, just like they want to kick us out, and we've been here for decades," one vendor told Italy's ANSA news agency.

"Sooner or later they'll even take away the gondoliers."

The battle against the birds is part of a broader campaign to improve decorum and cleanliness in the Unesco World Heritage Site which welcomes more than 1 million tourists a month.

Last year, stewards began patrolling St Mark's Square and other historic sites and can fine tourists found laying out a picnic, walking around bare-chested or dropping food wrappers.