Feeding ducks isn’t as helpful as it’s quacked up to be, as social media users across the country learned this week.

Twitter user @proudsIytherin tweeted a photo of a duck pond sign on Wednesday, warning visitors that it’s a common misconception that ducks can eat bread.

“Bread makes us ill, as it does not contain the right nutrition or calories that we need to keep us warm in the winter,” the sign reads, adding that grapes, lettuce and peas are better choices.

“I’VE BEEN FEEDING DUCKS BREAD THIS WHOLE TIME IM SO ASHAMED IM SUCH A MONSTER,” @proudsIytherin wrote.

It’s not known whether the Twitter user had fed ducks immediately before tweeting. The tweet has since gone viral, attracting more than 109,000 retweets and 154,000 likes as of Friday afternoon, and has inspired similar realizations about feeding ducks on social media.

On Long Island, where ducks have a long history, wildlife experts and parks officials have discouraged feeding ducks bread or even feeding them at all.

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“Waterfowl, whether it’s ducks or whatever, get ill from being fed bread and other items, so we prohibit feeding them,” said George Gorman, deputy regional director of the New York State Office of Parks, Recreation and Historic Preservation. The office oversees a number of parks with ducks, including Hempstead and Belmont Lakes.

In 2012, Old Brookville banned feeding ducks and other waterfowl on village property, with violators of the law subject to a $500 fine.

Water and environmental contamination, from rotting food to high concentrations of droppings from waterfowl that congregate around feeding areas, is just one of many negative consequences, according to the New York State Department of Environmental Conservation.

The DEC also warns that human feeding causes poor nutrition that can prevent the birds from flying. It also can lead to spread of disease among the animals; overcrowding; delayed migration; and gathering in unnatural and unsafe habitats, like parking lots.

Still, duck feeding is still allowed at some ponds across Long Island, including Duck Pond in East Hampton. There, the Ladies Village Improvement Society has installed signs that inform visitors what they can and can’t feed the ducks, according to their website.

If you do choose to feed ducks, the preferred meal is cracked corn or poultry feed, the society said. Some other options include uncooked oats, bird seed, chopped grapes, frozen peas and corn.

“We pride ourselves in counteracting the usual white-bread diet imposed by most tourists by concentrating on nutritional feed,” the website reads. “In the pleasant summer months when our population swells and our fat fowl are overfed, our focus morphs from feeding to upkeep – with an ever-vigilant eye.”